{ "cells": [ { "cell_type": "markdown", "metadata": { "id": "nmdxjrJq3dbh" }, "source": [ "# Implémentation d'un Chatbot documentaire (RAG)" ] }, { "cell_type": "markdown", "source": [ "# New Section" ], "metadata": { "id": "Zax03wW-ZorR" } }, { "cell_type": "code", "source": [ "from google.colab import drive\n", "drive.mount('/content/drive')" ], "metadata": { "id": "QZDRDZghJ5yc" }, "execution_count": null, "outputs": [] }, { "cell_type": "markdown", "metadata": { "id": "8CSP9YkO3k4s" }, "source": [ "## PARTIE 1 : Récupération de la base de données" ] }, { "cell_type": "markdown", "metadata": { "id": "mVJ7cbicJvSn" }, "source": [ "Les rapports du GIEC (**Groupe intergouvernemental d’experts sur l’évolution du climat**) ou IPCC en anglais, fournissent un état des lieux régulier des connaissances les plus avancées sur le changement climatique, ses causes, ses impacts et les mesures possibles pour l’atténuer et s’y adapter.\n", "\n", "La synthèse du sixième rapport d’évaluation du GIEC a été publiée le lundi 20 mars 2023. Fruit d’une collaboration internationale, ce nouveau rapport synthétise les connaissances scientifiques acquises entre 2015 et 2021. D'autres rapports ont été publiés entre temps sur des sujets spécifiques.\n", "\n", "Nous nous intéressons à quatre de ces documents:\n", "\n", "* Sixth Assessment Report\n", "* The Ocean and Cryosphere in a Changing Climate\n", "* Climate Change and Land\n", "* Global Warming of 1.5°C\n", "\n", "\n" ] }, { "cell_type": "markdown", "metadata": { "id": "kmQsEn6lDdhc" }, "source": [ "### 1. Récupération des documents" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "XbaJom4lm4oc" }, "outputs": [], "source": [ "# Créez un dossier 'RAG_IPCC' dans les fichiers de votre session colab" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "l7BAdBb23cLd", "colab": { "base_uri": "https://localhost:8080/" }, "outputId": "f67c4844-a414-49b8-ba7e-a2a3912edbdd" }, "outputs": [ { "output_type": "stream", "name": "stdout", "text": [ "Le dossier 'RAG_IPCC' existe déjà.\n", "6th_report a été téléchargé.\n", "ocean a été téléchargé.\n", "land a été téléchargé.\n", "warming a été téléchargé.\n" ] } ], "source": [ "# Téléchargez les 4 fichiers suivants dans ce dossier\n", "\n", "import os\n", "import requests\n", "\n", "# Chemin du dossier où vous souhaitez télécharger les fichiers\n", "chemin_dossier = \"/content/drive/My Drive/RAG_IPCC\"\n", "\n", "# Vérifier si le dossier existe, sinon le créer\n", "if not os.path.exists(chemin_dossier):\n", " os.makedirs(chemin_dossier)\n", " print(\"Le dossier 'RAG_IPCC' a été créé avec succès.\")\n", "else:\n", " print(\"Le dossier 'RAG_IPCC' existe déjà.\")\n", "\n", "# URLs des fichiers à télécharger\n", "urls = {\n", " \"6th_report\": \"https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6_SYR_FullVolume.pdf\",\n", " \"ocean\": \"https://www.ipcc.ch/site/assets/uploads/sites/3/2022/03/02_SROCC_TS_FINAL.pdf\",\n", " \"land\": \"https://www.ipcc.ch/site/assets/uploads/sites/4/2022/11/SRCCL_Technical-Summary.pdf\",\n", " \"warming\": \"https://www.ipcc.ch/site/assets/uploads/sites/2/2022/06/SPM_version_report_LR.pdf\"\n", "}\n", "\n", "# Télécharger les fichiers dans le dossier\n", "for name, url in urls.items():\n", " response = requests.get(url)\n", " with open(os.path.join(chemin_dossier, f\"{name}.pdf\"), 'wb') as file:\n", " file.write(response.content)\n", " print(f\"{name} a été téléchargé.\")\n" ] }, { "cell_type": "markdown", "metadata": { "id": "KRJNqRjZEc8S" }, "source": [ "### 2. Extraction du contenu textuel" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true, "id": "tf31A-7BQ_HD", "colab": { "base_uri": "https://localhost:8080/" }, "outputId": "777e45d5-df9b-41d5-df87-d16f6dfc71bb" }, "outputs": [ { "output_type": "stream", "name": "stdout", "text": [ "\u001b[1;30;43mLe flux de sortie a été tronqué et ne contient que les 5000 dernières lignes.\u001b[0m\n", "enhanced fishery \n", "productivity, improved \n", "water quality. Provision \n", "of food, medicine, fuel, \n", "wood and cultural \n", "benefits {4.4.2.3.5}Opportunity for \n", "community \n", "involvement,\n", "{4.4.2.3.1}Effective up to \n", "0.5 cm yr\n", "–¹ SLR. \n", "Strongly limited by \n", "ocean warming and \n", "acidification. \n", "Constrained at 1.5°C \n", "warming and lost at \n", "2°C at many places. \n", "{4.3.3.5.2, 4.4.2.3.2, \n", "5.3.4}\n", "Effective up to 0.5–1 \n", "cm yr–¹ SLR, \n", "decreased at 2°C \n", "{4.3.3.5.1, 4.4.2.3.2, \n", "5.3.7}(Marshes, Mangroves) \n", "(Marshes, \n", "Mangroves) High if the value of \n", "assets behind \n", "protection is high, as \n", "found in many urban and densely populated \n", "coastal areas \n", "{4.4.2.2.7}Destruction of habitat \n", "through coastal \n", "squeeze,flooding & \n", "erosion downdrift, \n", "lock-in, disastrous \n", "consequence in case \n", "of defence failure \n", "{4.3.2.4, 4.4.2.2.5}Predictable levels of \n", "safety {4.4.2.2.4}Multifunctional dikes \n", "such as for recreation, \n", "or other land use \n", "{4.4.2.2.5}Up to multiple metres \n", "of SLR {4.4.2.2.4}\n", "Effective but depends \n", "on sediment availability \n", "{4.4.2.2.4}High flexibility \n", "{4.4.2.2.4}Preservation of \n", "beaches for recreation/ \n", "tourism {4.4.2.2.5}Destruction of habitat, \n", "where sediment is \n", "sourced {4.4.2.2.5}High if tourism \n", "revenues are high \n", "{4.4.2.2.7}Conflicts about the \n", "distribution of public \n", "budgets {4.4.2.2.6}Confidence levels (assessed for effectiveness):The table illustrates responses and their characteristics. It is not exhaustive. Whether a response is applicable depends on ge ography and context.\n", "= Low = Medium = High = Very High(c) Responses to rising mean and extreme sea levels\n", "Enabling conditions Generic steps of adaptive decision making(d) Choosing and enabling sea level rise responses\n", "Implementation Monitoring and\n", "corrective action Stage setting Dynamic plan • Long-term perspective\n", "• Cross-scale coordination\n", "• Address vulnerability and equity \n", "• Inclusive public participation \n", "• Capability to address complexity Identify risks, \n", "objectives, options, \n", "uncertainties and \n", "criteria for evaluating \n", "options Develop initial plan \n", "(combinations of options over \n", "time) plus corrective actions \n", "to be carried out based on \n", "observed situationof initial plan and \n", "monitoring system \n", "for progressing \n", "change and success Monitor and take \n", "corrective action upon \n", "observed situationRetreat Ecosystem based adaptation\n", "Planned\n", "relocation\n", "Forced\n", "displacementReconciling the \n", "divergent interests \n", "arising from relocating \n", "people from point of \n", "origin and destination \n", "{4.4.2.6.6}\n", "Raises complex \n", "humanitarian questions \n", "on livelihoods, human \n", "rights and equity \n", "{4.4.2.6.6}Limited evidence \n", "[4.4.2.6.7}Loss of social cohesion, \n", "cultural identity and \n", "well-being. Depressed \n", "services (health, \n", "education, housing), job \n", "opportunities and \n", "economic growth \n", "{4.4.2.6.5} \n", "Range from loss of life \n", "to loss of livelihoods \n", "and sovereignty {4.4.2.6.5}Access to improved \n", "services (health, \n", "education, housing), \n", "job opportunities and \n", "economic growth \n", "{4.4.2.6.5}Sea level risks at \n", "origin can be \n", "eliminated {4.4.2.6.4}Effective if alternative \n", "safe localities are \n", "available {4.4.2.6.4}\n", "Addresses only \n", "immediate risk at place \n", "of originNot applicable Not applicable Not applicable(beyond risk reduction)\n", "Figure TS.7 | c, d\n", "61Technical Summary\n", "TSFigure TS.7 | Sea level rise risks and responses. The term response is used here instead of adaptation because some responses, such as retrea t, may or may not be \n", "considered to be adaptation. (a) shows the combined risk of coastal flooding, erosion and salinization for illustrative geographies in 2100, due to changing mea n and \n", "extreme sea levels under RCP2.6 and RCP8.5 and under two response scenarios. Risks under RCPs 4.5 and 6.0 were not assessed due to a lack of literature for the \n", "assessed geographies. The assessment does not account for changes in extreme sea level beyond those directly induced by mean se a level rise; risk levels could increase \n", "if other changes in extreme sea levels were considered (e.g., due to changes in cyclone intensity). Panel (a) considers a socioeconomic scenario with relatively stable \n", "coastal population density over the century. {SM4.3.2} Risks to illustrative geographies have been assessed based on relative s ea level changes projected for a set of \n", "specific examples: New York City, Shanghai and Rotterdam for resource-rich coastal cities covering a wide range of response expe riences; South Tarawa, Fongafale and \n", "Male’ for urban atoll islands; Mekong and Ganges-Brahmaputra-Meghna for large tropical agricultural deltas; and Bykovskiy, Shis hmaref, Kivalina, Tuktoyaktuk and Shingle \n", "Point for Arctic communities located in regions remote from rapid glacio-isostatic adjustment. {4.2, 4.3.4, SM4.2} The assessme nt distinguishes between two contrasting \n", "response scenarios. “No-to-moderate response” describes efforts as of today (i.e., no further significant action or new types of actions). “Maximum potential response” \n", "represents a combination of responses implemented to their full extent and thus significant additional efforts compared to today , assuming minimal financial, social and \n", "political barriers. The assessment has been conducted for each sea level rise and response scenario, as indicated by the burnin g embers in the figure; in-between risk levels \n", "are interpolated. {4.3.3} The assessment criteria include exposure and vulnerability (density of assets, level of degradation o f terrestrial and marine buffer ecosystems), \n", "coastal hazards (flooding, shoreline erosion, salinization), in-situ responses (hard engineered coastal defenses, ecosystem rest oration or creation of new natural buffers \n", "areas, and subsidence management) and planned relocation. Planned relocation refers to managed retreat or resettlement as descr ibed in Chapter 4, i.e., proactive and \n", "local-scale measures to reduce risk by relocating people, assets and infrastructure. Forced displacement is not considered in t his assessment. Panel (a) also highlights the \n", "relative contributions of in-situ responses and planned relocation to the total risk reduction. (b) schematically illustrates the risk reduction (vertical arrows) and risk delay \n", "(horizontal arrows) through mitigation and/or responses to sea level rise. (c) summarizes and assesses responses to sea level rise in terms of their effectiveness, costs, \n", "co-benefits, drawbacks, economic efficiency and associated governance challenges. {4.4.2} (d) presents generic steps of an adaptive decision-making approach, as well as \n", "key enabling conditions for responses to sea level rise. {4.4.4, 4.4.5} \n", "other processes associated with ocean physics and biogeochemistry, \n", "which cause the majority of the observed oxygen decline ( high \n", "confidence ). The oxygen minimum zones (OMZs) are expanding by \n", "a very likely range of 3–8%, most notably in the tropical oceans, but \n", "there is substantial decadal variability that affects the attribution \n", "of the overall oxygen declines to human activity in tropical regions \n", "(high confidence ). {5.2.2.4, Figure TS.3, Figure TS.5}\n", "In response to ocean warming and increased stratification, \n", "open ocean nutrient cycles are being perturbed and there \n", "is high confidence that this is having a regionally variable \n", "impact on primary producers. There is currently low confidence \n", "in appraising past open ocean productivity trends, including those determined by satellites, due to newly identified region-specific drivers of microbial growth and the lack of corroborating in situ time \n", "series datasets. {5.2.2.5, 5.2.2.6}\n", "Ocean warming has contributed to observed changes in \n", "biogeography of organisms ranging from phytoplankton to \n", "marine mammals ( high confidence ), consequently changing \n", "community composition ( high confidence ), and in some \n", "cases, altering interactions between organisms ( medium \n", "confidence ). Observed rate of range shifts since the 1950s and its \n", "very likely range are estimated to be 51.5 ± 33.3 km per decade \n", "and 29.0 ± 15.5 km per decade for organisms in the epipelagic and \n", "seafloor ecosystems, respectively. The direction of the majority of \n", "the shifts of epipelagic organisms are consistent with a response to \n", "warming ( high confidence ). {5.2.3, 5.3}\n", "Warming-induced range expansion of tropical species to higher \n", "latitudes has led to increased grazing on some coral reefs, rocky \n", "reefs, seagrass meadows and epipelagic ecosystems, leading \n", "to altered ecosystem structure ( medium confidence ). Warming, \n", "sea level rise (SLR) and enhanced loads of nutrients and sediments in \n", "deltas have contributed to salinisation and deoxygenation in estuaries \n", "(high confidence ), and have caused upstream redistribution of benthic \n", "and pelagic species according to their tolerance limits ( medium \n", "confidence ). {5.3.4, 5.3.5, 5.3.6, 5.2.3}\n", "Fisheries catches and their composition in many regions are \n", "already impacted by the effects of warming and changing primary production on growth, reproduction and survival \n", "of fish stocks ( high confidence ). Ocean warming and changes \n", "in primary production in the 20th century are related to changes \n", "in productivity of many fish stocks ( high confidence ), with an \n", "average decrease of approximately 3% per decade in population replenishment and 4.1% ( very likely range of 9.0% decline to \n", "0.3% increase) in maximum catch potential ( robust evidence, \n", "low agreement between fish stocks , medium confidence ). Species \n", "composition of fisheries catches since the 1970s in many shelf seas \n", "ecosystems of the world is increasing dominated by warm water \n", "species ( medium confidence ). {5.2.3, 5.4.1}\n", "Warming-induced changes in spatial distribution and abundance \n", "of fish stocks have already challenged the management of \n", "some important fisheries and their economic benefits ( high \n", "confidence ). For existing international and national ocean and fisheries \n", "governance, there are concerns about the reduced effectiveness to achieve mandated ecological, economic, and social objectives because of observed climate impacts on fisheries resources ( high confidence ). \n", "{5.4.2, 5.5.2}\n", "Coastal ecosystems are observed to be under stress from ocean warming and SLR that are exacerbated by non-climatic pressures from human activities on ocean and land ( high \n", "confidence ). Global wetland area has declined by nearly 50% \n", "relative to pre-industrial level as a result of warming, SLR, extreme \n", "climate events and other human impacts ( medium confidence ). \n", "Warming related mangrove encroachment into subtropical salt \n", "marshes has been observed in the past 50 years ( high confidence ). \n", "Distributions of seagrass meadows and kelp forests are contracting \n", "at low-latitudes that is attributable to warming ( high confidence ), \n", "and in some areas a loss of 36–43% following heat waves ( medium \n", "confidence ). Inundation, coastline erosion and salinisation are \n", "causing inland shifts in plant species distributions, which has been \n", "accelerating in the last decades ( medium confidence ). Warming has \n", "increased the frequency of large-scale coral bleaching events, causing \n", "worldwide reef degradation since 1997–1998 with cases of shifts to \n", "algal-dominated reefs ( high confidence ). Sessile calcified organisms \n", "(e.g.,  barnacles and mussels) in intertidal rocky shores are highly \n", "sensitive to extreme temperature events and acidification ( high \n", "confidence ), a reduction in their biodiversity and abundance have \n", "62Technical Summary\n", "TSbeen observed in naturally-acidified rocky reef ecosystems ( medium \n", "confidence ). Increased nutrient and organic matter loads in estuaries \n", "since the 1970s have exacerbated the effects of warming on bacterial respiration and eutrophication, leading to expansion of hypoxic areas (high confidence ). {5.3.1, 5.3.2, 5.3.4, 5.3.6}\n", "Coastal and near-shore ecosystems including salt marshes, \n", "mangroves and vegetated dunes in sandy beaches have a  varying capacity to build vertically and expand laterally in response to SLR. These ecosystems provide important services \n", "including coastal protection, carbon sequestration and habitat for \n", "diverse biota ( high confidence ). The carbon emission associated \n", "with the loss of vegetated coastal ecosystems is estimated to be \n", "0.04–1.46  Gt C yr\n", "–1 (high confidence ). The natural capacity of \n", "ecosystems to adapt to climate impacts may be limited by human activities that fragment wetland habitats and restrict landward migration ( high confidence ). {5.3.2, 5.3.3, 5.4.1, 5.5.1}\n", "Three out of the four major Eastern Boundary Upwelling \n", "Systems (EBUS) have shown large-scale wind intensification \n", "in the past 60 years ( high confidence ). However, the interaction \n", "of coastal warming and local winds may have affected upwelling strength, with the direction of changes varies between and within EBUS ( low confidence ). Increasing trends in ocean acidification in \n", "the California Current EBUS and deoxygenation in California Current \n", "and Humboldt Current EBUS are observed in the last few decades \n", "(high confidence ), although there is  low confidence   to distinguish \n", "anthropogenic forcing from internal climate variability. The expanding California EBUS OMZ has altered ecosystem structure and fisheries catches ( medium confidence ). {Box 5.3}\n", "Since the early 1980s, the occurrence of harmful algal blooms \n", "(HABs) and pathogenic organisms (e.g.,  Vibrio ) has increased \n", "in coastal areas in response to warming, deoxygenation and \n", "eutrophication, with negative impacts on food provisioning, \n", "tourism, the economy and human health ( high confidence ). These \n", "impacts depend on species-specific responses to the interactive effects \n", "of climate change and other human drivers (e.g.,  pollution). Human \n", "communities in poorly monitored areas are among the most vulnerable \n", "to these biological hazards ( medium confidence ). {Box 5.4, 5.4.2}\n", "Many frameworks for climate resilient coastal adaptation \n", "have been developed since AR5, with substantial variations \n", "in approach between and within countries, and across \n", "development status ( high confidence ). Few studies have assessed \n", "the success of implementing these frameworks due to the time-lag \n", "between implementation, monitoring, evaluation and reporting \n", "(medium confidence ). {5.5.2}\n", "Projections: scenarios and time horizons\n", "Climate models project significant changes in the ocean state \n", "over the coming century. Under the high emissions scenario \n", "(Representative Concentration Pathway (RCP)8.5) the impacts \n", "by 2090 are substantially larger and more widespread than for the low emissions scenario (RCP2.6) throughout the surface and deep ocean, including: warming ( virtually certain ); ocean \n", "acidification ( virtually certain ); decreased stability of mineral \n", "forms of calcite ( virtually certain ); oxygen loss ( very likely ); \n", "reduced near-surface nutrients ( likely as not ); decreased net \n", "primary productivity ( high confidence ); reduced fish production \n", "(likely ) and loss of key ecosystems services ( medium confidence ) \n", "that are important for human well-being and sustainable \n", "development. {5.2.2, Box 5.1, 5.2.3, 5.2.4, 5.4}\n", "By 2100 the ocean is very likely to warm by 2 to 4 times as much \n", "for low emissions (RCP2.6) and 5 to 7 times as much for the high emissions scenario (RCP8.5) compared with the observed \n", "changes since 1970. The 0–2000 m layer of the ocean is projected to \n", "warm by a further 2150 ZJ ( very likely range 1710–2790 ZJ) between \n", "2017 and 2100 for the RCP8.5 scenario. The 0–2000 m layer is projected to warm by 900 ZJ ( very likely range 650–1340 ZJ) by 2100 \n", "for the RCP2.6 scenario, and the overall warming of the ocean will \n", "continue this century even after radiative forcing and mean surface \n", "temperatures stabilise ( high confidence ). {5.2.2.2}\n", "The upper ocean will continue to stratify. By the end of the \n", "century the annual mean stratification of the top 200 m (averaged between 60ºS–60ºN relative to the 1986–2005 period) is projected to increase in the very likely range of 1–9% and 12–30% for RCP2.6 \n", "and RCP8.5 respectively. {5.2.2.2}\n", "It is very likely that the majority of coastal regions will \n", "experience statistically significant changes in tidal amplitudes \n", "over the course of the 21st century. The sign and amplitude of \n", "local changes to tides are very likely to be impacted by both human \n", "coastal adaptation measures and climate drivers. {5.2.2.2.3}\n", "It is virtually certain that surface ocean pH will decline, by \n", "0.036–0.042 or 0.287–0.29 pH units by 2081–2100, relative to 2006–2015, for the RCP2.6 or RCP8.5 scenarios, respectively. These pH changes are very likely to cause the Arctic and Southern \n", "Oceans, as well as the North Pacific and Northwestern Atlantic Oceans \n", "to become corrosive for the major mineral forms of calcium carbonate \n", "under RCP8.5, but these changes are virtually certain to be avoided \n", "under the RCP2.6 scenario. There is increasing evidence of an increase \n", "in the seasonal exposure to acidified conditions in the future ( high \n", "confidence ), with a very likely increase in the amplitude of seasonal \n", "cycle of hydrogen iron concentrations of 71–90% by 2100, relative to 2000 for the RCP8.5 scenario, especially at high latitudes. {5.2.2.3}\n", "Oxygen is projected to decline further. Globally, the oxygen content \n", "of the ocean is very likely to decline by 3.2–3.7% by 2081–2100, \n", "relative to 2006–2015, for the RCP8.5 scenario or by 1.6–2.0% for \n", "the RCP2.6 scenario. The volume of the oceans OMZ is projected to \n", "grow by a very likely range of 7.0 ± 5.6% by 2100 during the RCP8.5 \n", "scenario, relative to 1850–1900. The climate signal of oxygen loss \n", "will very likely emerge from the historical climate by 2050 with a very \n", "likely range of 59–80% of ocean area being affected by 2031–2050 \n", "and rising with a \n", "very likely range of 79–91% by 2081–2100 (RCP8.5 \n", "emissions scenario). The emergence of oxygen loss is very likely smaller \n", "in area for the RCP2.6 scenario in the 21st century and by 2090 the \n", "emerged area is declining. {5.2.2.4, Box 5.1 Figure 1}\n", "63Technical Summary\n", "TSOverall, nitrate concentrations in the upper 100 m are very \n", "likely to decline by 9–14% across CMIP5 models by 2081–2100, \n", "relative to 2006–2015, in response to increased stratification for RCP8.5, with medium confidence in these projections due \n", "to the limited evidence of past changes that can be robustly \n", "understood and reproduced by models. There is low confidence \n", "regarding projected increases in surface ocean iron levels due to systemic uncertainties in these models. {5.2.2.5}\n", "Climate models project that net primary productivity will very \n", "likely decline by 4–11% for RCP8.5 by 2081–2100, relative to \n", "2006–2015. The decline is due to the combined effects of warming, \n", "stratification, light, nutrients and predation and will show regional \n", "variations between low and high latitudes (l ow confidence ). The \n", "tropical ocean NPP will very likely decline by 7–16% for RCP8.5, with \n", "medium confidence as there are improved constraints from historical \n", "variability in this region. Globally, the sinking flux of organic matter \n", "from the upper ocean into the ocean interior is very likely to decrease \n", "by 9–16% for RCP8.5 in response to increased stratification and \n", "reduced nutrient supply, especially in tropical regions ( medium \n", "confidence ), which will reduce organic carbon supply to deep sea \n", "ecosystems ( high confidence ). The reduction in food supply to the deep sea is projected to lead to a 5–6% reduction in biomass of \n", "benthic biota over more than 97% of the abyssal seafloor by 2100 (medium confidence ). {5.2.2.6, 5.2.4.2, Figure TS.8}\n", "New ocean states for a broad suite of climate indices will \n", "progressively emerge over a substantial fractions of the ocean in the coming century (relative to past internal ocean variability), with Earth System Models (ESMs) showing an ordered emergence of first pH, followed by sea surface temperature (SST), interior oxygen, upper ocean nutrient levels and finally net primary production (NPP). The anthropogenic pH \n", "signal has very likely emerged for three quarters of the ocean prior to \n", "1950, with little difference between scenarios. Oxygen changes will \n", "very likely emerge over 59–80% of the ocean area by 2031–2050 \n", "and rises to 79–91% by 2081–2100 (RCP8.5 emissions scenario). \n", "The projected time of emergence for five primary drivers of marine ecosystem change (surface warming and acidification, oxygen loss, \n", "nitrate content and net primary production change) are all prior to \n", "2100 for over 60% of the ocean area under RCP8.5 and over 30% \n", "under RCP2.6 ( very likely ). {Box 5.1, Box 5.1 Figure 1}\n", "(c) M aximum fisheries catch potential\n", "(a) Simulated net primary production\n", "(b) Simulated total animal biomass\n", "Percent change\n", "Average by 2081–2100, relative to 1986–2005\n", "RCP2.6\n", " RCP8.5\n", "Value in normalized index (1986–2005)Value in mol C m–2 yr–1 (1986–2005) \n", "0 >25 10 20\n", "Observed values in tonnes* (1986–2005)\n", "model disagreement0 >275,000 0.15 55\n", "no data0> 3 0.5 1\n", "* See figure caption for details\n", "01 0 2 0 3 0 4 0 > 5 0 <–50 –40 –30 –20 –10\n", "Figure TS.8 | a, b , c\n", "64Technical Summary\n", "TS1.52345\n", "present day\n", "Abyssal\n", "plainsEstuaries Salt\n", "marshesMangrove\n", "forestsSeagrass\n", "meadowsSandy\n", "beachesWarm water\n", "coralsRocky\n", "shoresKelp\n", "forestsEpipelagic** Cold water\n", "corals(d) Impacts and risks to ocean ecosystems from climate change\n", "1234Global mean sea surface temperature (SST) \n", "change relative to pre-industrial levels (ºC)\n", "Confidence level for transition\n", "= Very high\n", "= High\n", "= Medium\n", "= Low\n", "= Transition rangeGlobal mean surface temperature (GMST) \n", "change relative to pre-industrial levels (ºC) 1\n", "0 0\n", "**see figure caption for definitionHigh Red: Significant and widespread impacts/risks.Level of added impacts/risks\n", "Very high\n", "Undetectable White: Impacts/risks are undetectable. Moderate Yellow: Impacts/risks are detectable and attributable to climate change with at least medium confidence.Purple: Very high probability of severe impacts/risks and the presence of significant irreversibility or the \n", "persistence of climate-related hazards, combined with limited ability to adapt due to the nature of the hazard \n", "or impacts/risks.\n", "Figure TS.8 | Projected changes, impacts and risks for ocean regions and ecosystems. (a) depth integrated net primary production (NPP from CMIP5)8, (b) total animal \n", "biomass (depth integrated, including fishes and invertebrates from FISHMIP)9, (c) maximum fisheries catch potential and (d) impacts and risks for coastal and open ocean \n", "ecosystems. The three left panels represent the simulated (a,b) and observed (c) mean values for the recent past (1986–2005), the middle and right panels represent \n", "projected changes (%) by 2081–2100 relative to recent past under low (RCP2.6) and high (RCP8.5) greenhouse gas emissions scenar io (see Table TS.2), respectively. Total \n", "animal biomass in the recent past (b, left panel) represents the projected total animal biomass by each spatial pixel relative to the global average. (c) *Average observed \n", "fisheries catch in the recent past (based on data from the Sea Around Us global fisheries database); projected changes in maximum fisheries catch potential in shelf seas \n", "are based on the average outputs from two fisheries and marine ecosystem models. To indicate areas of model inconsistency, shade d areas represent regions where models \n", "disagree in the direction of change for more than: (a) and (b) 3 out of 10 model projections, and (c) one out of two models. Although unshaded, the projected change in \n", "the Arctic and Antarctic regions in (b) total animal biomass and (c) fisheries catch potential have low confidence due to uncertainties associated with modelling multiple \n", "interacting drivers and ecosystem responses. Projections presented in (b) and (c) are driven by changes in ocean physical and biogeochemical conditions e.g., temperature, \n", "oxygen level, and net primary production projected from CMIP5 Earth system models. **The epipelagic refers to the uppermost par t of the ocean with depth <200 m from \n", "the surface where there is enough sunlight to allow photosynthesis. (d) Assessment of risks for coastal and open ocean ecosystems based on observed and projected \n", "climate impacts on ecosystem structure, functioning and biodiversity. Impacts and risks are shown in relation to changes in Glo bal Mean Surface Temperature (GMST) \n", "relative to pre-industrial level. Since assessments of risks and impacts are based on global mean Sea Surface Temperature (SST) , the corresponding SST levels are shown10. \n", "The assessment of risk transitions is described in Chapter 5 Sections 5.2, 5.3, 5.2.5 and 5.3.7 and Supplementary Materials SM5 .3, Table SM5.6, Table SM5.8 and other \n", "parts of the underlying report. The figure indicates assessed risks at approximate warming levels and increasing climate-related hazards in the ocean: ocean warming, \n", "acidification, deoxygenation, increased density stratification, changes in carbon fluxes, sea level rise, and increased frequency and/or intensity of extreme events. The \n", "assessment considers the natural adaptive capacity of the ecosystems, their exposure and vulnerability. Impact and risk levels do not consider risk reduction strategies such \n", "as human interventions, or future changes in non-climatic drivers. Risks for ecosystems were assessed by considering biological , biogeochemical, geomorphological and \n", "physical aspects. Higher risks associated with compound effects of climate hazards include habitat and biodiversity loss, chang es in species composition and distribution \n", "ranges, and impacts/risks on ecosystem structure and functioning, including changes in animal/plant biomass and density, produc tivity, carbon fluxes, and sediment \n", "transport. As part of the assessment, literature was compiled and data extracted into a summary table. A multi-round expert eli citation process was undertaken with \n", "independent evaluation of threshold judgement, and a final consensus discussion. Further information on methods and underlying l iterature can be found in Chapter 5, \n", "Sections 5.2 and 5.3 and Supplementary Material. {3.2.3, 3.2.4, 5.2, 5.3, 5.2.5, 5.3.7, SM5.6, SM5.8, Figure 5.16, Cross Chapte r Box 1 in Chapter 1 Table CCB1}\n", "8 NPP is estimated from the Coupled Models Intercomparison Project 5 (CMIP5).\n", "9 Total animal biomass is from the Fisheries and Marine Ecosystem Models Intercomparison Project (FISHMIP).\n", "10 The conversion between GMST and SST is based on a scaling factor of 1.44 derived from changes in an ensemble of RCP8.5 simulati ons; this scaling factor has \n", "an uncertainty of about 4% due to differences between the RCP2.6 and RCP8.5 scenarios. {Table SPM.1}\n", "65Technical Summary\n", "TSSimulated ocean warming and changes in NPP during the 21st \n", "century are projected to alter community structure of marine organisms ( high confidence ), reduce global marine animal \n", "biomass ( medium confidence ) and the maximum potential \n", "catches of fish stocks ( medium confidence ) with regional \n", "differences in the direction and magnitude of changes ( high \n", "confidence ). The global biomass of marine animals, including those \n", "that contribute to fisheries, is projected to decrease with a very likely \n", "range under RCP2.6 and RCP8.5 of 4.3 ± 2.0% and 15.0 ± 5.9%, \n", "respectively, by 2080–2099 relative to 1986–2005. The maximum catch potential is projected to decrease by 3.4% to 6.4% (RCP2.6) \n", "and 20.5% to 24.1% (RCP8.5) in the 21st century. {5.4.1}\n", "Projected decreases in global marine animal biomass and \n", "fish catch potential could elevate the risk of impacts on \n", "income, livelihood and food security of the dependent human \n", "communities ( medium confidence ). Projected climate change \n", "impacts on fisheries also increase the risk of potential conflicts among \n", "fishery area users and authorities or between two different communities \n", "within the same country ( medium confidence ), exacerbated through \n", "competing resource exploitation from international actors and \n", "mal-adapted policies ( low confidence ). {5.2.3, 5.4, 5.5.3}\n", "Projected decrease in upper ocean export of organic carbon \n", "to the deep seafloor is expected to result in a loss of animal \n", "biomass on the deep seafloor by 5.2 –17.6% by 2090–2100 \n", "compared to the present (2006–2015) under RCP8.5 with regional variations ( medium confidence ). Some increases are \n", "projected in the polar regions, due to enhanced stratification in \n", "the surface ocean, reduced primary production and shifts towards \n", "small phytoplankton ( medium confidence ). The projected impacts on \n", "biomass in the abyssal seafloor are larger under RCP8.5 than RCP4.5 \n", "(very likely ). The increase in climatic hazards beyond thresholds of \n", "tolerance of deep sea organisms will increase the risk of loss of \n", "biodiversity and impacts on functioning of deep water column and \n", "seafloor that is important to support ecosystem services, such as \n", "carbon sequestration ( medium confidence ). {5.2.4}\n", "Structure and functions of all types of coastal ecosystems \n", "will continue to be at moderate to high risk under the \n", "RCP2.6 scenario ( medium confidence ) and will face high to \n", "very high risk under the RCP8.5 scenario ( high confidence ) \n", "by 2100. Seagrass meadows ( high confidence ) and kelp forests \n", "(high confidence ) will face moderate to high risk at temperature \n", "above 1.5ºC global sea surface warming. Coral reefs will face very \n", "high risk at temperatures 1.5ºC of global sea surface warming \n", "(very high confidence ). Intertidal rocky shores are also expected \n", "to be at very high risk (transition above 3ºC) under the RCP8.5 \n", "scenario ( medium confidence ). These ecosystems have low to \n", "moderate adaptive capacity, as they are highly sensitive to ocean temperatures and acidification. The ecosystems with moderate to high risk (transition above 1.8ºC) under future emissions scenarios \n", "are mangrove forests, sandy beaches, estuaries and salt marshes \n", "(medium confidence ). Estuaries and sandy beaches are subject \n", "to highly dynamic hydrological and geomorphological processes, \n", "giving them more natural adaptive capacity to climate hazards. In \n", "these systems, sediment relocation, soil accretion and landward expansion of vegetation may initially mitigate against flooding and \n", "habitat loss, but salt marshes in particular will be at very high risk in the context of SLR and extreme climate-driven erosion under RCP8.5. {5.3, Figure 5.16}\n", "Expected coastal ecosystem responses over the 21st century \n", "are habitat contraction, migration and loss of biodiversity \n", "and functionality. Pervasive human coastal disturbances will limit \n", "natural ecosystem adaptation to climate hazards ( high confidence ). \n", "Global coastal wetlands will lose between 20–90% of their area depending on emissions scenario with impacts on their contributions to carbon sequestration and coastal protection ( high confidence ). \n", "Kelp forests at low-latitudes and temperate seagrass meadows will \n", "continue to retreat as a result of intensified extreme temperatures, \n", "and their low dispersal ability will elevate the risk of local extinction \n", "under RCP8.5 ( high confidence ). Intertidal rocky shores will continue \n", "to be affected by ocean acidification, warming, and extreme heat \n", "exposure during low tide emersion, causing reduction of calcareous \n", "species and loss of ecosystem biodiversity and complexity shifting \n", "towards algae dominated habitats ( high confidence ). Salinisation and \n", "expansion of hypoxic conditions will intensify in eutrophic estuaries, especially in mid and high latitudes with microtidal regimes ( high \n", "confidence ). Sandy beach ecosystems will increasingly be at risk of \n", "eroding, reducing the habitable area for dependent organisms ( high \n", "confidence ). {5.3, 5.4.1}\n", "Almost all coral reefs will degrade from their current state, even \n", "if global warming remains below 2ºC ( very high confidence ), \n", "and the remaining shallow coral reef communities will differ in species composition and diversity from present reefs ( very \n", "high confidence ). These declines in coral reef health will greatly \n", "diminish the services they provide to society, such as food provision \n", "(high confidence ), coastal protection ( high confidence ) and tourism \n", "(medium confidence ). {5.3.4, 5.4.1}\n", "Multiple hazards of warming, deoxygenation, aragonite under-\n", "saturation and decrease in flux of organic carbon from the \n", "surface ocean will decrease calcification and exacerbate the \n", "bioerosion and dissolution of the non-living component of cold \n", "water coral. Habitat-forming, cold water corals will be vulnerable \n", "where temperature and oxygen exceed the species’ thresholds \n", "(medium confidence ). Reduced particulate food supply is projected \n", "to be experienced by 95% of cold water coral ecosystems by 2100 \n", "under RCP8.5 relative to the present, leading to a very likely range of \n", "8.6 ± 2% biomass loss ( medium confidence ). {5.2.4, Box 5.2}\n", "Anthropogenic changes in EBUS will emerge primarily in the \n", "second half of the 21st century ( medium confidence ). EBUS will \n", "be impacted by climate change in different ways, with strong regional \n", "variability with consequences for fisheries, recreation and climate \n", "regulation ( medium confidence ). The Pacific EBUS are projected \n", "to have calcium carbonate undersaturation in surface waters \n", "within a few decades under RCP8.5 ( high confidence ); combined \n", "with warming and decreasing oxygen levels, this will increase the \n", "impacts on shellfish larvae, benthic invertebrates and demersal fishes \n", "(high confidence ) and related fisheries and aquaculture ( medium \n", "confidence ). The inherent natural variability of EBUS, together with \n", "66Technical Summary\n", "TSuncertainties in present and future trends in the intensity and \n", "seasonality of upwelling, coastal warming and stratification, primary production and biogeochemistry of source waters poses large challenges in projecting the response of EBUS to climate change and to the adaptation of governance of biodiversity conservation and living marine resources in EBUS ( high confidence ). {Box 5.3}\n", "Climate change impacts on ecosystems and their goods \n", "and services threatens key cultural dimensions of lives and \n", "livelihoods. These threats include erosion of Indigenous and \n", "non-indigenous culture, their knowledge about the ocean and \n", "knowledge transmission, reduced access to traditional food, loss of opportunities for aesthetic and spiritual appreciation of the ecosystems, and marine recreational activities ( medium confidence ). \n", "Ultimately, these can lead to the loss of part of people’s cultural \n", "identity and values beyond the rate at which identify and values can \n", "be adjusted or substituted ( medium confidence ). {5.4.2}\n", "Climate change increases the exposure and bioaccumulation \n", "of contaminants such as persistent organic pollutants and \n", "mercury ( medium confidence ), and their risk of impacts on \n", "marine ecosystems and seafood safety ( high agreement, \n", "medium evidence, medium confidence ). Such risks are particularly \n", "large for top predators and for human communities that have high \n", "consumption on these organisms, including coastal Indigenous \n", "communities ( medium confidence ). {5.4.2}\n", "Shifting distributions of fish stocks between governance \n", "jurisdictions will increase the risk of potential conflicts among \n", "fishery area users and authorities or between two different \n", "communities within the same country ( medium confidence ). \n", "These fishery governance related risks are widespread under high \n", "emissions scenarios with regional hotspots ( medium confidence ), \n", "and highlight the limits of existing natural resource management \n", "frameworks for addressing ecosystem change ( high confidence ). \n", "{5.2.5, 5.4.2.1.3, 5.5, 5.5.2}\n", "Response options to enhance resilience\n", "There is clear evidence for observed climate change impacts \n", "throughout the ocean with consequences for human \n", "communities and require options to reduce risks and impacts. \n", "Coastal blue carbon can contribute to mitigation for many nations but its global scope is modest (offset of <2% of current emissions) ( likely ). Some ocean indices are expected \n", "to emerge earlier than others (e.g.,  warming, acidification and effects on fish stocks) and could therefore be used to prioritise planning and building resilience. The survival of some keystone ecosystems (e.g., coral reefs) are at risk, while governance structures are not well-matched to the spatial and temporal scale of climate change impacts on ocean systems. Ecosystem restoration may be able to locally reduce climate risks ( medium confidence ) but at relatively high cost and \n", "effectiveness limited to low emissions scenarios and to less \n", "sensitive systems ( high confidence ). {5.2, 5.3, 5.4, 5.5}Coastal blue carbon ecosystems, such as mangroves, salt \n", "marshes and seagrasses, can help reduce the risks and impacts of climate change, with multiple co-benefits. Some 151 countries \n", "around the world contain at least one of these coastal blue carbon ecosystems and 71 countries contain all three. Below-ground carbon storage in vegetated marine habitats can be up to 1000 tC ha\n", "–1, much \n", "higher than most terrestrial ecosystems ( high confidence ). Successful \n", "implementation of measures to maintain and promote carbon storage in such coastal ecosystems could assist several countries in achieving a balance between emissions and removals of greenhouse gases ( medium confidence ). Conservation of these habitats would \n", "also sustain the wide range of ecosystem services they provide and assist with climate adaptation through improving critical habitats for biodiversity, enhancing local fisheries production, and protecting \n", "coastal communities from SLR and storm events ( high confidence ). \n", "The climate mitigation effectiveness of other natural carbon removal processes in coastal waters, such as seaweed ecosystems and proposed non-biological marine CO\n", "2 removal methods, are smaller or \n", "currently have higher associated uncertainties. Seaweed aquaculture \n", "warrants further research attention. {5.5.1.1, 5.5.1.1, 5.5.1, 5.5.2, 5.5.1.1.3, 5.5.1.1.4}\n", "The potential climatic benefits of blue carbon ecosystems \n", "can only be a very modest addition to, and not a replacement \n", "for, the very rapid reduction of greenhouse gas emissions. \n", "The maximum global mitigation benefits of cost-effective coastal \n", "wetland restoration is unlikely to be more than 2% of current \n", " \n", "total emissions from all sources. Nevertheless, the protection \n", "and enhancement of coastal blue carbon can be an important \n", "contribution to both mitigation and adaptation at the national scale. \n", "The feasibility of climate mitigation by open ocean fertilisation of \n", "productivity is limited to negligible, due to the likely decadal-scale \n", "return to the atmosphere of nearly all the extra carbon removed, \n", "associated difficulties in carbon accounting, risks of unintended \n", "side effects and low acceptability. Other human interventions to \n", "enhance marine carbon uptake, for example, ocean alkalinisation \n", "(enhanced weathering), would also have governance challenges, \n", "with the increased risk of undesirable ecological consequences ( high \n", "confidence ). {5.5.1.2}\n", "Socioinstitutional adaptation responses are more frequently \n", "reported in the literature than ecosystem-based and built \n", "infrastructure approaches. Hard engineering responses are more \n", "effective when supported by ecosystem-based adaptation (EbA) \n", "approaches ( high agreement ), and both approaches are enhanced by \n", "combining with socioinstitutional approaches for adaptation ( high \n", "confidence ). Stakeholder engagement is necessary ( robust evidence, \n", "high agreement ). {5.5.2}\n", "EbA is a cost-effective coastal protection tool that can \n", "have many co-benefits, including supporting livelihoods, \n", "contributing to carbon sequestration and the provision of \n", "a range of other valuable ecosystem services ( high confidence ). \n", "Such adaptation does, however, assume that the climate can be \n", "stabilised. Under changing climatic conditions there are limits to the \n", "effectiveness of ecosystem-based adaptation, and these limits are \n", "currently difficult to determine. {5.5.2.1}\n", "67Technical Summary\n", "TSSocioinstitutional adaptation responses, including community-\n", "based adaptation, capacity-building, participatory processes, institutional support for adaptation planning and support mechanisms for communities are important tools to address climate change impacts ( high confidence ). For fisheries \n", "management, improving coordination of integrated coastal management and marine protected areas (MPAs) have emerged in the literature as important adaptation governance responses ( robust \n", "evidence, medium agreement ). {5.5.2.2, 5.5.2.6}\n", "Observed widespread decline in warm water corals has led \n", "to the consideration of alternative restoration approaches to enhance climate resilience. Approaches, such as ‘coral reef \n", "gardening’ have been tested, and ecological engineering and \n", "other approaches such as assisted evolution, colonisation and \n", "chimerism are being researched for reef restoration. However, \n", "the effectiveness of these approaches to increase resilience to \n", "climate stressors and their large-scale implementation for reef \n", "restoration will be limited unless warming and ocean acidification \n", "are rapidly controlled ( high confidence ). {Box 5.5, 5.5.2}\n", "Existing ocean governance structures are already facing \n", "multi-dimensional, scale-related challenges because of climate \n", "change. This trend of increasing complexity will continue ( high \n", "confidence ). The mechanisms for the governance of marine Areas \n", "Beyond National Jurisdiction (ABNJ), such as ocean acidification, would benefit from further development ( high confidence ). There \n", "is also scope to increase the overall effectiveness of international \n", "and national ocean governance regimes by increasing cooperation, \n", "integration and widening participation ( medium confidence ). Diverse \n", "adaptations of ocean related governance are being tried, and some are \n", "producing promising results. However, rigorous evaluation is needed of \n", "the effectiveness of these adaptations in achieving their goals. {5.5.3}\n", "There are a broad range of identified barriers and limits \n", "for adaptation to climate change in ecosystems and human \n", "systems ( high confidence ). Limitations include the space that \n", "ecosystems require, non-climatic drivers and human impacts that need \n", "to be addressed as part of the adaptation response, the lowering of \n", "adaptive capacity of ecosystems because of climate change, and the \n", "slower ecosystem recovery rates relative to the recurrence of climate \n", "impacts, availability of technology, knowledge and financial support \n", "and existing governance structures ( medium confidence ). {5.5.2}\n", "TS.6 Extremes, Abrupt Changes \n", "and Managing Risks\n", "This chapter assesses extremes and abrupt or irreversible changes in \n", "the ocean and cryosphere in a changing climate, to identify regional \n", "hot spots, cascading effects, their impacts on human and natural \n", "systems, and sustainable and resilient risk management strategies. It is not comprehensive in terms of the systems assessed and some information on extremes, abrupt and irreversible changes, in particular for the cryosphere, may be found in other chapters.Ongoing and Emerging Changes in the Ocean \n", "and Cryosphere, and their Impacts on Ecosystems and Human Societies\n", "Anthropogenic climate change has increased observed \n", "precipitation ( medium confidence ), winds ( low confidence ), \n", "and extreme sea level events ( high confidence ) associated \n", "with some tropical cyclones, which has increased intensity of \n", "multiple extreme events and associated cascading impacts \n", "(high confidence ). Anthropogenic climate change may have \n", "contributed to a poleward migration of maximum tropical cyclone \n", "intensity in the western North Pacific in recent decades related to \n", "anthropogenically-forced tropical expansion ( low confidence ). \n", "There is emerging evidence for an increase in the annual global proportion of Category 4 or 5 tropical cyclones in recent decades \n", "(low confidence ). {6.3, Table 6.2, Figure 6.2, Box 6.1}\n", "Changes in Arctic sea ice have the potential to influence \n", "mid-latitude weather ( medium confidence ), but there is low \n", "confidence in the detection of this influence for specific \n", "weather types. {6.3}\n", "Extreme wave heights, which contribute to extreme sea level \n", "events, coastal erosion and flooding, have increased in the \n", "Southern and North Atlantic Oceans by around 1.0 cm yr\n", "–1 and \n", "0.8 cm yr–1 over the period 1985–2018 ( medium confidence ). \n", "Sea ice loss in the Arctic has also increased wave heights over \n", "the period 1992–2014 ( medium confidence ). {6.3}\n", "Marine heatwaves (MHWs), periods of extremely high ocean \n", "temperatures, have negatively impacted marine organisms \n", "and ecosystems in all ocean basins over the last two decades, \n", "including critical foundation species such as corals, seagrasses \n", "and kelps ( very high confidence ). Globally, marine heat related \n", "events have increased; marine heatwaves, defined when the daily sea surface temperature exceeds the local 99th percentile over the period 1982 to 2016, have doubled in frequency and have become longer-\n", "lasting, more intense and more extensive ( very likely ). It is very likely \n", "that between 84–90% of marine heatwaves that occurred between \n", "2006 and 2015 are attributable to the anthropogenic temperature \n", "increase. {6.4, Figures 6.3, 6.4}\n", "Both palaeoclimate and modern observations suggest that the \n", "strongest El Niño and La Niña events since the pre-industrial \n", "period have occurred during the last fifty years ( medium \n", "confidence ). There have been three occurrences of extreme El Niño \n", "events during the modern observational period (1982–1983, \n", "1997–1998, 2015–2016), all characterised by pronounced rainfall \n", "in the normally dry equatorial East Pacific. There have been two \n", "occurrences of extreme La Niña (1988–1989, 1998–1999). El Niño \n", "and La Niña variability during the last 50 years is unusually high \n", "compared with average variability during the last millennium. \n", "{6.5, Figure 6.5}\n", "The equatorial Pacific trade wind system experienced an \n", "unprecedented intensification during 2001 –2014, resulting in \n", "enhanced ocean heat transport from the Pacific to the Indian \n", "68Technical Summary\n", "TSOcean, influencing the rate of global temperature change \n", "(medium confidence ). In the last two decades, total water transport \n", "from the Pacific to the Indian Ocean by the Indonesian Throughflow (ITF), and the Indian Ocean to Atlantic Ocean has increased ( high confidence ). \n", "Increased ITF has been linked to Pacific cooling trends and basin-wide \n", "warming trends in the Indian Ocean. Pacific sea surface temperature (SST) cooling trends and strengthened trade winds have been linked to an anomalously warm tropical Atlantic. {6.6, Figure 6.7}\n", "Observations, both in situ (2004–2017) and based on sea \n", "surface temperature reconstructions, indicate that the Atlantic \n", "Meridional Overturning Circulation (AMOC) has weakened relative to 1850–1900 ( medium confidence ). There is insufficient \n", "data to quantify the magnitude of the weakening, or to properly \n", "attribute it to anthropogenic forcing due to the limited length of the \n", "observational record. Although attribution is currently not possible, \n", "CMIP5 model simulations of the period 1850–2015, on average, \n", "exhibit a weakening AMOC when driven by anthropogenic forcing. \n", "{6.7, Figure 6.8}\n", "Climate change is modifying multiple types of climate-related \n", "events or hazards in terms of occurrence, intensity and \n", "periodicity. It increases the likelihood of compound hazards \n", "that comprise simultaneously or sequentially occurring events \n", "to cause extreme impacts in natural and human systems. \n", "Compound events in turn trigger cascading impacts ( high \n", "confidence ). Three case studies are presented in the chapter, \n", "(i)  Tasmania’s Summer of 2015–2016, (ii) The Coral Triangle and \n", "(ii) Hurricanes of 2017. {6.8, Box 6.1}\n", "Projections of Ocean and Cryosphere Change \n", "and Hazards to Ecosystems and Human Society Under Low and High Emission Futures\n", "The average intensity of tropical cyclones, the proportion \n", "of Category 4 and 5 tropical cyclones and the associated \n", "average precipitation rates are projected to increase for a 2ºC \n", "global temperature rise above any baseline period ( medium \n", "confidence ). Rising mean sea levels will contribute to higher \n", "extreme sea levels associated with tropical cyclones ( very high \n", "confidence ). Coastal hazards will be exacerbated by an increase in \n", "the average intensity, magnitude of storm surge and precipitation rates of tropical cyclones. There are greater increases projected under RCP8.5 than under RCP2.6 from around mid-century to 2100 \n", "(medium confidence ). There is low confidence in changes in the \n", "future frequency of tropical cyclones at the global scale. {6.3.1}\n", "Significant wave heights (the average height from trough to \n", "crest of the highest one-third of waves) are projected to increase \n", "across the Southern Ocean and tropical eastern Pacific ( high \n", "confidence ) and Baltic Sea ( medium confidence ) and decrease \n", "over the North Atlantic and Mediterranean Sea under RCP8.5 \n", "(high confidence ). Coastal tidal amplitudes and patterns are projected \n", "to change due to sea level rise and coastal adaptation measures ( very \n", "likely ). Projected changes in waves arising from changes in weather patterns, and changes in tides due to sea level rise, can locally enhance \n", "or ameliorate coastal hazards ( medium confidence ). {6.3.1, 5.2.2}\n", "Marine heatwaves are projected to further increase in \n", "frequency, duration, spatial extent and intensity (maximum temperature) ( very high confidence ). Climate models project \n", "increases in the frequency of marine heatwaves by 2081–2100, \n", "relative to 1850–1900, by approximately 50 times under RCP8.5 and \n", "20 times under RCP2.6 ( medium confidence ). The largest increases \n", "in frequency are projected for the Arctic and the tropical oceans \n", "(medium confidence ). The intensity of marine heatwaves is projected \n", "to increase about 10-fold under RCP8.5 by 2081–2100, relative to \n", "1850–1900 ( medium confidence ). {6.4}\n", "Extreme El Niño and La Niña events are projected to likely \n", "increase in frequency in the 21st century and to likely intensify \n", "existing hazards, with drier or wetter responses in several regions across the globe. Extreme El Niño events are projected to \n", "occur about as twice as often under both RCP2.6 and RCP8.5 in the 21st century when compared to the 20th century ( medium confidence ). \n", "Projections indicate that extreme Indian Ocean Dipole events also \n", "increase in frequency ( low confidence ). {6.5, Figures 6.5, 6.6}\n", "Lack of long-term sustained Indian and Pacific Ocean \n", "observations, and inadequacies in the ability of climate models to simulate the magnitude of trade wind decadal variability and the inter-ocean link, mean there is low confidence in \n", "future projections of the trade wind system. {6.6, Figure 6.7}\n", "The AMOC will very likely weaken over the 21st century ( high \n", "confidence ), although a collapse is very unlikely (medium \n", "confidence ). Nevertheless, a substantial weakening of the \n", "AMOC remains a physically plausible scenario. Such a weakening \n", "would strongly impact natural and human systems, leading to \n", "a decrease in marine productivity in the North Atlantic, more winter \n", "storms in Europe, a reduction in Sahelian and South Asian summer rainfall, a decrease in the number of TCs in the Atlantic, and an increase in regional sea level around the Atlantic especially along the northeast coast of North America ( medium confidence ). Such impacts would be \n", "superimposed on the global warming signal. {6.7, Figure 6.8}\n", "Impacts from further changes in TCs and ETCs, MHWs, extreme \n", "El Niño and La Niña events and other extremes will exceed the limits of resilience and adaptation of ecosystems and people, leading to unavoidable loss and damage ( medium \n", "confidence ). {6.9.2}\n", "Strengthening the Global Responses in the Context \n", "of Sustainable Development Goals (SDGs) and Charting Climate Resilient Development Pathways for Oceans and Cryosphere\n", "There is medium confidence that including extremes and abrupt \n", "changes, such as AMOC weakening, ice sheet collapse (West \n", "Antarctic Ice Sheet (WAIS) and Greenland Ice Sheet (GIS)), \n", "leads to a several-fold increase in the cost of carbon emissions \n", "69Technical Summary\n", "TS(medium confidence ). If carbon emissions decline, the risk of \n", "extremes and abrupt changes are reduced, creating co-benefits. {6.8.6}\n", "For TCs and ETCs, investment in disaster risk reduction, flood \n", "management (ecosystem and engineered) and early warning systems decreases economic loss ( medium confidence ), but \n", "such investments may be hindered by limited local capacities, such as increased losses and mortality from extreme winds and storm surges in less developed countries despite adaptation efforts. There is emerging evidence of increasing risks for locations \n", "impacted by unprecedented storm trajectories ( low confidence ). \n", "Managing the risk from such changing storm trajectories and intensity \n", "proves challenging because of the difficulties of early warning and its \n", "receptivity by the affected population ( high confidence ). {6.3, 6.9}\n", "Limiting global warming would reduce the risk of impacts of \n", "MHWs, but critical thresholds for some ecosystems (e.g., kelp \n", "forests, coral reefs) will be reached at relatively low levels of \n", "future global warming ( high confidence ). Early warning systems, \n", "producing skillful forecasts of MHWs, can further help to reduce the \n", "vulnerability in the areas of fisheries, tourism and conservation, but \n", "are yet unproven at large scale ( medium confidence ). {6.4}\n", "Sustained long-term monitoring and improved forecasts \n", "can be used in managing the risks of extreme El Niño and La Niña events associated with human health, agriculture, fisheries, coral reefs, aquaculture, wildfire, drought and flood \n", "management ( high confidence ). {6.5}\n", "Extreme change in the trade wind system and its impacts \n", "on global variability, biogeochemistry, ecosystems and \n", "society have not been adequately understood and represent \n", "significant knowledge gaps. {6.6}\n", "By 2300, an AMOC collapse is as likely as not for high emission \n", "pathways and very unlikely for lower ones, highlighting that \n", "an AMOC collapse can be avoided in the long term by CO\n", "2 \n", "mitigation ( medium confidence ). Nevertheless, the human impact \n", "of these physical changes have not been sufficiently quantified and \n", "there are considerable knowledge gaps in adaptation responses to \n", "a substantial AMOC weakening. {6.7}\n", "The ratio between risk reduction investment and reduction of \n", "damages of extreme events varies. Investing in preparation and prevention against the impacts from extreme events is very likely less than the cost of impacts and recovery ( medium \n", "confidence ). Coupling insurance mechanisms with risk reduction \n", "measures can enhance the cost-effectiveness of adapting to climate \n", "change ( medium confidence ). {6.9}\n", "Climate change adaptation and disaster risk reduction require \n", "capacity building and an integrated approach to ensure \n", "trade-offs between short- and long-term gains in dealing \n", "with the uncertainty of increasing extreme events, abrupt changes and cascading impacts at different geographic scales \n", "(high confidence ). {6.9}\n", "Limiting the risk from the impact of extreme events and abrupt \n", "changes leads to successful adaptation to climate change \n", "with the presence of well-coordinated climate-affected sectors and disaster management relevant agencies ( high \n", "confidence ). Transformative governance inclusive of successful \n", "integration of disaster risk management (DRM) and climate \n", "change adaptation, empowerment of vulnerable groups, and \n", "accountability of governmental decisions promotes climate-resilient development pathways ( high confidence ). {6.9}\n", "TS.7 Low-lying Islands and Coasts \n", "(Integrative Cross-Chapter Box)\n", "Ocean and cryosphere changes already impact Low-Lying \n", "Islands and Coasts (LLIC), including Small Island Developing \n", "States (SIDS), with cascading and compounding risks. Disproportionately higher risks are  expected  in the course of the 21st century. Reinforcing the findings of the IPCC \n", "Special Report on Global Warming of 1.5ºC, vulnerable human \n", "communities, especially those in coral reef environments and \n", "polar regions, may exceed adaptation limits well before the \n", "end of this century and even in a low greenhouse gas emission \n", "pathway ( high confidence ). Depending on the effectiveness of \n", "21st century mitigation and adaptation pathways under all \n", "emission scenarios, most of the low-lying regions around the \n", "world may face  adaptation limits beyond 2100, due to the long-term commitment of sea level rise ( medium confidence ). \n", "LLIC  host around 11% of the global population, generate about 14% of the global Gross Domestic Product and comprise many world cultural heritage sites. LLIC already experience climate-related \n", "ocean and cryosphere changes ( high confidence ), and they share \n", "both commonalities in their exposure and vulnerability to climate \n", "change (e.g.,  low elevation, human disturbances to terrestrial \n", "and marine ecosystems), and context-specificities (e.g., variable \n", "ecosystem climate sensitivities and risk perceptions by populations). \n", "Options to adapt to rising seas, e.g., range from hard engineering \n", "to ecosystem-based measures, and from securing current settings to \n", "relocating people, built assets and activities. Effective combinations \n", "of measures vary across geographies (cities and megacities, small \n", "islands, deltas and Arctic coasts), and reflect the scale of observed \n", "and projected impacts, ecosystems’ and societies’ adaptive capacity, \n", "and the existence of transformational governance ( high confidence ) \n", "{Sections 3.5.3, 4.4.2 to 4.4.5, 5.5.2, 6.8, 6.9, Cross-Chapter \n", "Box 2 in Chapter 1}.\n", "\n", "35\n", "Foreword \n", "and PrefaceTechnical \n", "Summary\n", "\n", "TS37\n", "Technical\n", "Summary\n", "Editors:\n", "Priyadarshi R. Shukla (India), Jim Skea (United Kingdom), Raphael Slade (United Kingdom) \n", "Renée van Diemen (The Netherlands/United Kingdom), Eamon Haughey (Ireland), Juliette \n", "Malley (United Kingdom), Minal Pathak (India), Joana Portugal Pereira (United Kingdom) \n", "Drafting Authors:\n", "Fahmuddin Agus (Indonesia), Almut Arneth (Germany), Paulo Artaxo (Brazil), Humberto \n", "Barbosa (Brazil), Luis G. Barioni (Brazil), Tim G. Benton (United Kingdom), Suruchi Bhadwal \n", "(India), Katherine Calvin (The United States of America), Eduardo Calvo (Peru), Donovan \n", "Campbell (Jamaica), Francesco Cherubini (Italy), Sarah Connors (France/United Kingdom), \n", "Annette Cowie (Australia), Edouard Davin (France/Switzerland), Kenel Delusca (Haiti), \n", "Fatima Denton (The Gambia), Aziz Elbehri (Morocco), Karlheinz Erb (Italy), Jason Evans \n", "(Australia), Dulce Flores-Renteria (Mexico), Felipe Garcia-Oliva (Mexico), Giacomo Grassi \n", "(Italy/European Union), Kathleen Hermans (Germany), Mario Herrero (Australia/Costa \n", "Rica), Richard Houghton (The  United States of America), Joanna House (United Kingdom), \n", "Mark Howden (Australia), Margot Hurlbert (Canada), Ismail Abdel Galil Hussein (Egypt), \n", "Muhammad Mohsin Iqbal (Pakistan), Gensuo Jia (China), Esteban Jobbagy (Argentina), Francis \n", "X. Johnson (Sweden), Joyce Kimutai (Kenya), Kaoru Kitajima (Japan), Tony Knowles (South \n", "Africa), Vladimir Korotkov (The Russian Federation), Murukesan V. Krishnapillai (Micronesia/\n", "India), Jagdish Krishnaswamy (India), Werner Kurz (Canada), Anh Le Hoang (Viet Nam), \n", "Christopher Lennard (South Africa), Diqiang Li (China), Emma Liwenga (The United Republic of \n", "Tanzania), Shuaib Lwasa (Uganda), Nagmeldin Mahmoud (Sudan), Valérie Masson-Delmotte \n", "(France), Cheikh Mbow (Senegal), Pamela McElwee (The United States of America), Carlos \n", "Fernando Mena (Ecuador), Francisco Meza (Chile), Alisher Mirzabaev (Germany/Uzbekistan), \n", "John Morton (United Kingdom), Wilfran Moufouma-Okia (France), Soojeong Myeong (The \n", "Republic of Korea), Dalila Nedjraoui (Algeria), Johnson Nkem (Cameroon), Ephraim Nkonya \n", "(The United Republic of Tanzania), Nathalie De  Noblet-Ducoudré (France), Lennart Olsson \n", "(Sweden), Balgis Osman Elasha (Côte d’Ivoire), Jan Petzold (Germany), Ramón Pichs-Madruga \n", "(Cuba), Elvira Poloczanska (United Kingdom), Alexander Popp (Germany), Hans-Otto Pörtner \n", "(Germany), Prajal Pradhan (Germany/Nepal), Mohammad Rahimi (Iran), Andy Reisinger (New \n", "Zealand), Marta G. Rivera-Ferre (Spain), Debra C. Roberts (South Africa), Cynthia Rosenzweig \n", "38\n", "Technical Summary\n", "TS(The United States of America), Mark Rounsevell (United Kingdom), Nobuko Saigusa (Japan), \n", "Tek Sapkota (Canada/Nepal), Elena Shevliakova (The United States of America), Andrey Sirin \n", "(The Russian Federation), Pete Smith (United Kingdom), Youba Sokona (Mali), Denis Jean \n", "Sonwa (Cameroon), Jean-Francois Soussana (France), Adrian Spence (Jamaica), Lindsay \n", "Stringer (United Kingdom), Raman Sukumar (India), Miguel Angel Taboada (Argentina), Fasil \n", "Tena (Ethiopia), Francesco N. Tubiello (The United States of America/Italy), Murat Türkeş \n", "(Turkey), Riccardo Valentini (Italy), Ranses José Vázquez Montenegro (Cuba), Louis Verchot \n", "(Colombia/The United States of America), David Viner (United Kingdom), Koko Warner \n", "(The United States of America), Mark Weltz (The United States of America), Nora M. Weyer \n", "(Germany), Anita Wreford (New Zealand), Jianguo Wu (China), Yinlong Xu (China), Noureddine \n", "Yassaa (Algeria), Sumaya Zakieldeen (Sudan), Panmao Zhai (China), Zinta Zommers (Latvia)\n", "Chapter Scientists:\n", "Yuping Bai (China), Aliyu Salisu Barau (Nigeria), Abdoul Aziz Diouf (Senegal), Baldur  Janz \n", "(Germany), Frances Manning (United Kingdom), Erik Mencos Contreras (The United \n", "States of America/Mexico), Dorothy Nampanzira (Uganda), Chuck Chuan Ng (Malaysia), \n", "Helen Berga Paulos (Ethiopia), Xiyan Xu (China), Thobekile Zikhali (Zimbabwe)\n", "This Technical Summary should be cited as: \n", "P .R. Shukla, J. Skea, R. Slade, R. van Diemen, E. Haughey, J. Malley, M. Pathak, J. Portugal Pereira (eds.) Technical \n", "Summary, 2019. In: Climate Change and Land: an IPCC special report on climate change, desertification, land \n", "degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems \n", "[P .R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D. C. Roberts, P . Zhai, R. Slade, S. Connors, \n", "R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P . Vyas, E. Huntley, \n", "K. Kissick, M, Belkacemi, J. Malley, (eds.)]. https://doi.org/10.1017/9781009157988.002\n", "39\n", "Technical SummaryTSTable of Contents\n", "TS.0 Introduction ������������������������������������������������������������������������������������������ 40\n", "TS.1 Framing and context ��������������������������������������������������������������������� 40\n", "TS.2 Land–climate interactions �������������������������������������������������������� 44\n", "TS.3 Desertification ������������������������������������������������������������������������������������ 50\n", "TS.4 Land degradation ����������������������������������������������������������������������������� 53\n", "TS.5 Food security ���������������������������������������������������������������������������������������� 56\n", "TS.6 Interlinkages between desertification, land \n", "degradation, food security and greenhouse \n", "gas fluxes ������������������������������������������������������������������������������������������������ 61\n", "TS.7 Risk management and decision making \n", "in relation to sustainable development ������������������������ 67\n", "40\n", "Technical Summary\n", "TSTS.0 Introduction\n", "This Technical Summary to the IPCC Special Report on Climate \n", "Change and Land (SRCCL)1 comprises a compilation of the chapter \n", "executive summaries illustrated with figures from the report. It \n", "follows the structure of the SRCCL (Figure TS.1) and is presented \n", "in seven parts. TS.1 (Chapter 1) provides a synopsis of the main \n", "issues addressed in the Special Report, introducing key concepts \n", "and definitions and highlighting where the report builds on \n", "previous publications. TS.2 (Chapter 2) focuses on the dynamics of \n", "the land–climate system (Figure TS.2). It assesses recent progress \n", "towards understanding the impacts of climate change on land, and \n", "the feedbacks land has on climate and which arise from altered \n", "biogeochemical and biophysical fluxes between the atmosphere and \n", "the land surface. TS.3 (Chapter 3) examines how the world’s dryland \n", "populations are uniquely vulnerable to desertification and climate \n", "change, but also have significant knowledge in adapting to climate \n", "variability and addressing desertification. TS.4 (Chapter 4) assesses \n", "the urgency of tackling land degradation across all land ecosystems. \n", "Despite accelerating trends of land degradation, reversing these \n", "trends is attainable through restoration efforts and improved land \n", "management, which is expected to improve resilience to climate \n", "change, mitigate climate change, and ensure food security for \n", "generations to come. TS.5 (Chapter 5) focuses on food security, \n", "with an assessment of the risks and opportunities that climate \n", "change presents to food systems. It considers how mitigation and \n", "adaptation can contribute to both human and planetary health. TS.6 \n", "(Chapter 6) introduces options for responding to the challenges of \n", "desertification, land degradation and food security and evaluates the \n", "trade-offs for sustainable land management, climate adaptation and \n", "mitigation, and the sustainable development goals. TS.7 (Chapter 7) \n", "further assesses decision making and policy responses to risks in the \n", "climate-land-human system. TS.1 Framing and context\n", "Land, including its water bodies, provides the basis for human \n", "livelihoods and well-being through primary productivity, the \n", "supply of food, freshwater, and multiple other ecosystem \n", "services (high confidence). Neither our individual or societal \n", "identities, nor the world’s economy would exist without the \n", "multiple resources, services and livelihood systems provided by \n", "land ecosystems and biodiversity. The annual value of the world’s \n", "total terrestrial ecosystem services has been estimated at 75 trillion \n", "USD in 2011, approximately equivalent to the annual global Gross \n", "Domestic Product (based on USD2007 values) (medium confidence). \n", "Land and its biodiversity also represent essential, intangible benefits \n", "to humans, such as cognitive and spiritual enrichment, sense of \n", "belonging and aesthetic and recreational values. Valuing ecosystem \n", "services with monetary methods often overlooks these intangible \n", "services that shape societies, cultures and quality of life and the \n", "intrinsic value of biodiversity. The Earth’s land area is finite. Using \n", "land resources sustainably is fundamental for human well-being \n", "(high confidence). {1.1.1}\n", "The current geographic spread of the use of land, the large \n", "appropriation of multiple ecosystem services and the loss \n", "of biodiversity are unprecedented in human history (high \n", "confidence). By 2015, about three-quarters of the global ice-free land \n", "surface was affected by human use. Humans appropriate one-quarter \n", "to one-third of global terrestrial potential net primary production \n", "(high confidence). Croplands cover 12–14% of the global ice-free \n", "surface. Since 1961, the supply of global per capita food calories \n", "increased by about one-third, with the consumption of vegetable \n", "oils and meat more than doubling. At the same time, the use of \n", "inorganic nitrogen fertiliser increased by nearly ninefold, and the use \n", "of irrigation water roughly doubled (high confidence). Human use, \n", "at varying intensities, affects about 60–85% of forests and 70–90% \n", "of other natural ecosystems (e.g., savannahs, natural grasslands) \n", "(high confidence). Land use caused global biodiversity to decrease by \n", "around 11–14% (medium confidence). (Figure TS.2). {1.1.2}\n", " \n", "Figure TS.1 | Overview of the IPCC Special Report on Climate Change and Land (SRCCL).\n", "1 The full title of the report is the IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in \n", "terrestrial ecosystemsNatural system dynamics (Chapter 2)\n", "Desertification (Chapter 3) Framing\n", "and \n", "context\n", "(Chapter 1) Degradation (Chapter 4)\n", "Food security (Chapter 5) Risks and decision-making\n", "(Chapter 7)Synergies, trade-offs,\n", "integrated response\n", "options (Chapter 6)...\n", "41\n", "Technical SummaryTS\n", "Figure TS.2 | Land use and observed climate change: A representation of the principal land challenges and land–climate system processes covered \n", "in this assessment report.Land use and observed climate change\n", "SPM approved draft IPCC SRCCL | Page 4 Subject to copy edit and layout1\n", "2\n", "3Prevalence of overweight + obese\n", "4Prevalence of underweightTotal calories per capitaPopulationCHANGE in EMISSIONS since 1961B. GHG emissions\n", "An estimated 23% of total anthropogenic \n", "greenhouse gas emissions (2007–2016)\n", "derive from Agriculture, Forestry and \n", "Other Land Use (AFOLU).\n", "E. Food demand \n", "Increases in production are linked to \n", "consumption changes. F. Desertification and \n", "land degradation \n", "Land-use change, land-use intensification \n", "and climate change have contributed to \n", "desertification and land degradation.\n", "CHANGE in % rel. to 1961 and 1970 CHANGE in % rel. to 1961 and 1975 \n", "1\n", "2\n", "3Inland wetland extentDryland areas in drought annually Population in areas experiencing desertification 1\n", "2\n", "3\n", "CHANGE in % rel. to 1961\n", "1\n", "2\n", "3Irrigation water volume\n", "4Total number of ruminant livestock Cereal yieldsInorganic N fertiliser useIntensive pasture 2%12% (12 – 14%) 1% (1 – 1%) 37% (30 – 47%) 22% (16 – 23%) 28% (24 – 31%)\n", "Used savannahs and\n", "shrublands 16% Plantation forests 2%\n", "Forests managed for timber\n", "and other uses 20% Irrigated cropland 2%Infrastructure 1%\n", "Non-irrigated cropland 10%Unforested ecosystems with\n", "minimal human use 7%\n", "Forests (intact or primary)\n", "with minimal human use 9% \n", "Other land (barren, rock) 12%Global ice-free land surface 100% (130 Mkm/two.numr)\n", "0\n", "10\n", "20\n", "30Net CO/two.dnom emissions from FOLU (GtCO/two.dnom yr–1)\n", "N/two.dnomO emissions from Agriculture (GtCO/two.dnomeq yr–1)CH/four.dnom emissions from Agriculture (GtCO/two.dnomeq yr–1)A. Observed temperature change relative to 1850–1900 \n", "Since the pre-industrial period (1850–1900) the observed mean land surface air \n", "temperature has risen considerably more than the global mean surface (land and ocean) \n", "temperature (GMST). \n", "C. Global land use\n", "in circa 2015\n", "The barchart depicts \n", "shares of different uses \n", "of the global, ice-free \n", "land area. Bars are \n", "ordered along a gradient \n", "of decreasing land-use \n", "intensity from le/f_t to right. \n", " Extensive pasture 19%D. Agricultural production \n", "Land use change and rapid land use \n", "intensification have supported the \n", "increasing production of food, feed and \n", "fibre. Since 1961, the total production of \n", "food (cereal crops) has increased by 240% \n", "(until 2017) because of land area \n", "expansion and increasing yields. Fibre \n", "production (cotton) increased by 162% \n", "(until 2013). \n", "21\n", "3%\n", "%\n", "50\n", "-50150250\n", "100\n", "0200%\n", "50\n", "-50150250\n", "100\n", "0200\n", "1\n", "2\n", "3\n", "441\n", "2\n", "31850 1880 1900 1920 1940 1960 1980 2000 20182\n", "046\n", "1\n", "2\n", "30.51.5\n", "1\n", "0\n", "-0.52CHANGE in TEMPERATURE rel. to 1850–1900 (°C)\n", "Change in \n", "surface air \n", "temperature \n", "over land (°C)\n", "Change in global \n", "(land-ocean) \n", "mean surface \n", "temperature \n", "(GMST) (°C)GtCO/two.dnomeq yr–1\n", "1961 1980 2000 2016\n", "1961 1980 2000 2017 1961 1980 2000 201750\n", "-50150250300700\n", "100\n", "0200\n", "1961 1980 2000 2017800\n", "42\n", "Technical Summary\n", "TSWarming over land has occurred at a faster rate than the global \n", "mean and this has had observable impacts on the land system \n", "(high confidence). The average temperature over land for the period \n", "2006–2015 was 1.53°C higher than for the period 1850–1900, and \n", "0.66°C larger than the equivalent global mean temperature change. \n", "These warmer temperatures (with changing precipitation patterns) \n", "have altered the start and end of growing seasons, contributed to \n", "regional crop yield reductions, reduced freshwater availability, and \n", "put biodiversity under further stress and increased tree mortality (high \n", "confidence). Increasing levels of atmospheric CO2, have contributed \n", "to observed increases in plant growth as well as to increases in woody \n", "plant cover in grasslands and savannahs (medium confidence). {1.1.2}\n", "Urgent action to stop and reverse the over-exploitation of \n", "land resources would buffer the negative impacts of multiple \n", "pressures, including climate change, on ecosystems and society \n", "(high confidence). Socio-economic drivers of land use change such \n", "as technological development, population growth and increasing \n", "per capita demand for multiple ecosystem services are projected to \n", "continue into the future (high confidence). These and other drivers \n", "can amplify existing environmental and societal challenges, such \n", "as the conversion of natural ecosystems into managed land, rapid \n", "urbanisation, pollution from the intensification of land management \n", "and equitable access to land resources (high confidence). Climate \n", "change will add to these challenges through direct, negative impacts \n", "on ecosystems and the services they provide (high confidence). Acting \n", "immediately and simultaneously on these multiple drivers would \n", "enhance food, fibre and water security, alleviate desertification, and \n", "reverse land degradation, without compromising the non-material or \n", "regulating benefits from land (high confidence). {1.1.2, 1.2.1, 1.3.2–\n", "1.3.6, Cross-Chapter Box 1 in Chapter 1}\n", "Rapid reductions in anthropogenic greenhouse gas (GHG) \n", "emissions that restrict warming to “well-below” 2°C would \n", "greatly reduce the negative impacts of climate change on \n", "land ecosystems (high confidence). In the absence of rapid \n", "emissions reductions, reliance on large-scale, land-based, \n", "climate change mitigation is projected to increase, which \n", "would aggravate existing pressures on land (high confidence). \n", "Climate change mitigation efforts that require large land areas (e.g., \n", "bioenergy and afforestation/reforestation) are projected to compete \n", "with existing uses of land (high confidence). The competition for land could increase food prices and lead to further intensification \n", "(e.g., fertiliser and water use) with implications for water and air \n", "pollution, and the further loss of biodiversity (medium confidence). \n", "Such consequences would jeopardise societies’ capacity to achieve \n", "many Sustainable Development Goals (SDG) that depend on land \n", "(high confidence). {1.3.1, Cross-Chapter Box 2 in Chapter 1}\n", "Nonetheless, there are many land-related climate change \n", "mitigation options that do not increase the competition for \n", "land (high confidence). Many of these options have co-benefits \n", "for climate change adaptation (medium confidence). Land use \n", "contributes about one-quarter of global greenhouse gas emissions, \n", "notably CO2 emissions from deforestation, CH4 emissions from rice \n", "and ruminant livestock and N2O emissions from fertiliser use (high \n", "confidence). Land ecosystems also take up large amounts of carbon \n", "(high confidence). Many land management options exist to both \n", "reduce the magnitude of emissions and enhance carbon uptake. These \n", "options enhance crop productivity, soil nutrient status, microclimate \n", "or biodiversity, and thus, support adaptation to climate change (high \n", "confidence). In addition, changes in consumer behaviour, such as \n", "reducing the over-consumption of food and energy would benefit the \n", "reduction of GHG emissions from land (high confidence). The barriers \n", "to the implementation of mitigation and adaptation options include \n", "skills deficit, financial and institutional barriers, absence of incentives, \n", "access to relevant technologies, consumer awareness and the limited \n", "spatial scale at which the success of these practices and methods \n", "have been demonstrated. {1.2.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6}\n", "Sustainable food supply and food consumption, based on \n", "nutritionally balanced and diverse diets, would enhance \n", "food security under climate and socio-economic changes \n", "(high confidence). Improving food access, utilisation, quality and \n", "safety to enhance nutrition, and promoting globally equitable diets \n", "compatible with lower emissions have demonstrable positive impacts \n", "on land use and food security (high confidence). Food security is also \n", "negatively affected by food loss and waste (estimated as 25–30% of \n", "total food produced) (medium confidence). Barriers to improved food \n", "security include economic drivers (prices, availability and stability of \n", "supply) and traditional, social and cultural norms around food eating \n", "practices. Climate change is expected to increase variability in food \n", "production and prices globally (high confidence), but the trade in food \n", "commodities can buffer these effects. Trade can provide embodied Figure TS.2 (continued): Panels A-F show the status and trends in selected land use and climate variables that represent many of the core topics covered in this report. \n", "The annual time series in B and D–F are based on the most comprehensive, available data from national statistics, in most cases from FAOSTAT which starts in 1961. \n", "Y-axes in panels D–F are expressed relative to the starting year of the time series (rebased to zero). Data sources and notes: A: The warming curves are averages of \n", "four datasets {2.1; Figure 2.2; Table 2.1} B: N2O and CH4 from agriculture are from FAOSTAT; Net CO2 emissions from FOLU using the mean of two bookkeeping models \n", "(including emissions from peatland fires since 1997). All values expressed in units of CO2-eq are based on AR5 100-year Global Warming Potential values without \n", "climate-carbon feedbacks (N2O = 265; CH4 = 28). {see Table SPM.1, 1.1, 2.3} C: Depicts shares of different uses of the global, ice-free land area for approximately the \n", "year 2015, ordered along a gradient of decreasing land-use intensity from left to right. Each bar represents a broad land cover category; the numbers on top are the total \n", "% of the ice-free area covered, with uncertainty ranges in brackets. Intensive pasture is defined as having a livestock density greater than 100 animals/km². The area of \n", "‘forest managed for timber and other uses’ was calculated as total forest area minus ‘primary/intact’ forest area. {1.2, Table 1.1, Figure 1.3} D: Note that fertiliser use is \n", "shown on a split axis. The large percentage change in fertiliser use reflects the low level of use in 1961 and relates to both increasing fertiliser input per area as well as \n", "the expansion of fertilised cropland and grassland to increase food production. {1.1, Figure 1.3} E: Overweight population is defined as having a body mass index (BMI) \n", ">25 kg m-2; underweight is defined as BMI <18.5 kg m-2. {5.1, 5.2} F: Dryland areas were estimated using TerraClimate precipitation and potential evapotranspiration \n", "(1980–2015) to identify areas where the Aridity Index is below 0.65. Population data are from the HYDE3.2 database. Areas in drought are based on the 12-month \n", "accumulation Global Precipitation Climatology Centre Drought Index. The inland wetland extent (including peatlands) is based on aggregated data from more than 2000 \n", "time series that report changes in local wetland area over time. {3.1, 4.2, 4.6}\n", "43\n", "Technical SummaryTSflows of water, land and nutrients (medium confidence). Food \n", "trade can also have negative environmental impacts by displacing \n", "the effects of overconsumption (medium confidence). Future food \n", "systems and trade patterns will be shaped as much by policies as by \n", "economics (medium confidence). {1.2.1, 1.3.3}\n", "A gender-inclusive approach offers opportunities to enhance \n", "the sustainable management of land (medium confidence). \n", "Women play a significant role in agriculture and rural economies \n", "globally. In many world regions, laws, cultural restrictions, patriarchy \n", "and social structures such as discriminatory customary laws and norms \n", "reduce women’s capacity in supporting the sustainable use of land \n", "resources (medium confidence). Therefore, acknowledging women’s \n", "land rights and bringing women’s land management knowledge into \n", "land-related decision-making would support the alleviation of land \n", "degradation, and facilitate the take-up of integrated adaptation and \n", "mitigation measures (medium confidence). {1.4.1, 1.4.2}\n", "Regional and country specific contexts affect the capacity to \n", "respond to climate change and its impacts, through adaptation \n", "and mitigation (high confidence). There is large variability in the \n", "availability and use of land resources between regions, countries and \n", "land management systems. In addition, differences in socio-economic \n", "conditions, such as wealth, degree of industrialisation, institutions \n", "and governance, affect the capacity to respond to climate change, \n", "food insecurity, land degradation and desertification. The capacity \n", "to respond is also strongly affected by local land ownership. Hence, \n", "climate change will affect regions and communities differently (high \n", "confidence). {1.3, 1.4}Cross-scale, cross-sectoral and inclusive governance can \n", "enable coordinated policy that supports effective adaptation \n", "and mitigation (high confidence). There is a lack of coordination \n", "across governance levels, for example, local, national, transboundary \n", "and international, in addressing climate change and sustainable \n", "land management challenges. Policy design and formulation is often \n", "strongly sectoral, which poses further barriers when integrating \n", "international decisions into relevant (sub)national policies. \n", "A portfolio of policy instruments that are inclusive of the diversity \n", "of governance actors would enable responses to complex land and \n", "climate challenges (high confidence). Inclusive governance that \n", "considers women’s and indigenous people’s rights to access and use \n", "land enhances the equitable sharing of land resources, fosters food \n", "security and increases the existing knowledge about land use, which \n", "can increase opportunities for adaptation and mitigation (medium \n", "confidence). {1.3.5, 1.4.1, 1.4.2, 1.4.3}\n", "Scenarios and models are important tools to explore the \n", "trade-offs and co-benefits of land management decisions \n", "under uncertain futures (high confidence). Participatory, co-\n", "creation processes with stakeholders can facilitate the use of \n", "scenarios in designing future sustainable development strategies \n", "(medium confidence). In addition to qualitative approaches, models \n", "are critical in quantifying scenarios, but uncertainties in models arise \n", "from, for example, differences in baseline datasets, land cover classes \n", "and modelling paradigms (medium confidence). Current scenario \n", "approaches are limited in quantifying time-dependent policy and \n", "management decisions that can lead from today to desirable futures \n", "or visions. Advances in scenario analysis and modelling are needed to \n", "better account for full environmental costs and non-monetary values \n", "as part of human decision-making processes. {1.2.2, Cross-Chapter \n", "Box 1 in Chapter 1}\n", "44Technical Summary\n", "TSTS.2 Land–climate interactions \n", "Implications of climate change, variability\n", "and extremes for land systems\n", "It is certain that globally averaged land surface air \n", "temperature (LSAT) has risen faster than the global mean \n", "surface temperature (i.e., combined LSAT and sea surface \n", "temperature) from the preindustrial period (1850–1900) to \n", "the present day (1999–2018). According to the single longest \n", "and most extensive dataset, from 1850–1900 to 2006–2015 \n", "mean land surface air temperature has increased by 1.53°C \n", "(very likely range from 1.38°C to 1.68°C) while global mean \n", "surface temperature has increased by 0.87°C (likely range \n", "from 0.75°C to 0.99°C). For the 1881–2018 period, when four \n", "independently produced datasets exist, the LSAT increase \n", "was 1.41°C (1.31–1.51°C), where the range represents the \n", "spread in the datasets’ median estimates. Analyses of paleo \n", "records, historical observations, model simulations and underlying \n", "physical principles are all in agreement that LSATs are increasing \n", "at a higher rate than SST as a result of differences in evaporation, \n", "land–climate feedbacks and changes in the aerosol forcing over land \n", "(very high confi dence). For the 2000–2016 period, the land-to-ocean \n", "warming ratio (about 1.6) is in close agreement between different \n", "observational records and the CMIP5 climate model simulations (the \n", "likely range of 1.54–1.81). {2.2.1}Anthropogenic warming has resulted in shifts of climate \n", "zones, primarily as an increase in dry climates and decrease \n", "of polar climates (high confi dence). Ongoing warming is \n", "projected to result in new, hot climates in tropical regions and \n", "to shift climate zones poleward in the mid- to high latitude \n", "and upward in regions of higher elevation (high confi dence).\n", "Ecosystems in these regions will become increasingly exposed to \n", "temperature and rainfall extremes beyond the climate regimes they \n", "are currently adapted to (high confi dence), which can alter their \n", "structure, composition and functioning. Additionally, high-latitude \n", "warming is projected to accelerate permafrost thawing and increase \n", "disturbance in boreal forests through abiotic (e.g., drought, fi re) \n", "and biotic (e.g., pests, disease) agents (high confi dence). {2.2.1, \n", "2.2.2, 2.5.3}\n", "Globally, greening trends (trends of increased photosynthetic \n", "activity in vegetation) have increased over the last 2–3 decades \n", "by 22–33%, particularly over China, India, many parts of \n", "Europe, central North America, southeast Brazil and southeast \n", "Australia (high confi dence). This results from a combination of direct \n", "(i.e., land use and management, forest conservation and expansion) \n", "and indirect factors (i.e., CO2 fertilisation, extended growing season, \n", "global warming, nitrogen deposition, increase of diffuse radiation) \n", "linked to human activities (high confi dence). Browning trends (trends \n", "of decreasing photosynthetic activity) are projected in many regions \n", "where increases in drought and heatwaves are projected in a warmer \n", "climate. There is low confi dence in the projections of global greening \n", "and browning trends. {2.2.4, Cross-Chapter Box 4 in Chapter 2}\n", "Figure TS.3 | The structure and functioning of managed and unmanaged ecosystems that affect local, regional and global climate. Land surface \n", "characteristics such as albedo and emissivity determine the amount of solar and long-wave radiation absorbed by land and refl ected or emitted to the atmosphere. Surface \n", "roughness infl uences turbulent exchanges of momentum, energy, water and biogeochemical tracers. Land ecosystems modulate the atmospheric composition through \n", "emissions and removals of many GHGs and precursors of SLCFs, including biogenic volatile organic compounds (BVOCs) and mineral dust. Atmospheric aerosols formed \n", "from these precursors affect regional climate by altering the amounts of precipitation and radiation reaching land surfaces through their role in clouds physics.\n", "precipitation\n", "fertilizer\n", "fertilizerfertilizer\n", "fertilizer\n", " mineral \n", "aerosols\n", "carbonaceous \n", " aerosols\n", "CH4,N2OCH4\n", "CO2CO2 CO2\n", "CO2\n", "BVOCs BVOCsN deposition\n", "& emissionsensible \n", " heatcondensation\n", " evaporationsolar radiation\n", "albedo CO2CO2\n", "wind\n", "long wave radiation\n", "emissivity\n", "agriculture forestry unmanaged landssoil carbon\n", "& nutrientssoil carbon\n", "& nutrientssoil carbon\n", "& nutrients\n", "roughness\n", "\n", "45\n", "Technical SummaryTSThe frequency and intensity of some extreme weather and \n", "climate events have increased as a consequence of global \n", "warming and will continue to increase under medium and high \n", "emission scenarios (high confidence). Recent heat-related events, \n", "for example, heatwaves, have been made more frequent or intense \n", "due to anthropogenic GHG emissions in most land regions and the \n", "frequency and intensity of drought has increased in Amazonia, north-\n", "eastern Brazil, the Mediterranean, Patagonia, most of Africa and \n", "north-eastern China (medium confidence). Heatwaves are projected \n", "to increase in frequency, intensity and duration in most parts of \n", "the world (high confidence) and drought frequency and intensity is \n", "projected to increase in some regions that are already drought prone, \n", "predominantly in the Mediterranean, central Europe, the southern \n", "Amazon and southern Africa (medium confidence). These changes \n", "will impact ecosystems, food security and land processes including \n", "GHG fluxes (high confidence). {2.2.5}\n", "Climate change is playing an increasing role in determining \n", "wildfire regimes alongside human activity (medium \n", "confidence), with future climate variability expected to \n", "enhance the risk and severity of wildfires in many biomes such \n", "as tropical rainforests (high confidence). Fire weather seasons \n", "have lengthened globally between 1979 and 2013 (low confidence). \n", "Global land area burned has declined in recent decades, mainly due \n", "to less burning in grasslands and savannahs (high confidence). While \n", "drought remains the dominant driver of fire emissions, there has \n", "recently been increased fire activity in some tropical and temperate \n", "regions during normal to wetter than average years due to warmer \n", "temperatures that increase vegetation flammability (medium \n", "confidence). The boreal zone is also experiencing larger and more \n", "frequent fires, and this may increase under a warmer climate (medium \n", "confidence). {Cross-Chapter Box 4 in Chapter 2}\n", "Terrestrial greenhouse gas fluxes on unmanaged and \n", "managed lands\n", "Agriculture, forestry and other land use (AFOLU) is a significant \n", "net source of GHG emissions (high confidence), contributing \n", "to about 23% of anthropogenic emissions of carbon dioxide \n", "(CO2), methane (CH4) and nitrous oxide (N2O) combined as \n", "CO2 equivalents in 2007–2016 (medium confidence). AFOLU \n", "results in both emissions and removals of CO2, CH4 and N2O to and \n", "from the atmosphere (high confidence). These fluxes are affected \n", "simultaneously by natural and human drivers, making it difficult to \n", "separate natural from anthropogenic fluxes (very high confidence). \n", "(Figure TS.3) {2.3}\n", "The total net land-atmosphere flux of CO2 on both managed \n", "and unmanaged lands very likely provided a global net \n", "removal from 2007 to 2016 according to models (-6.0 ± 3.7 \n", "GtCO2 yr–1, likely range). This net removal is comprised of two major \n", "components: (i) modelled net anthropogenic emissions from AFOLU \n", "are 5.2 ± 2.6 GtCO2 yr–1 (likely range) driven by land cover change, \n", "including deforestation and afforestation/reforestation, and wood \n", "harvesting (accounting for about 13% of total net anthropogenic \n", "emissions of CO2) (medium confidence), and (ii) modelled net removals \n", "due to non-anthropogenic processes are 11.2 ± 2.6 GtCO2 yr–1 (likely range) on managed and unmanaged lands, driven by environmental \n", "changes such as increasing CO2, nitrogen deposition and changes in \n", "climate (accounting for a removal of 29% of the CO2 emitted from \n", "all anthropogenic activities (fossil fuel, industry and AFOLU) (medium \n", "confidence). {2.3.1}\n", "Global models and national GHG inventories use different \n", "methods to estimate anthropogenic CO2 emissions and \n", "removals for the land sector. Consideration of differences \n", "in methods can enhance understanding of land sector net \n", "emission such as under the Paris Agreement’s global stocktake \n", "(medium confidence). Both models and inventories produce \n", "estimates that are in close agreement for land-use change involving \n", "forest (e.g., deforestation, afforestation), and differ for managed \n", "forest. Global models consider as managed forest those lands that \n", "were subject to harvest whereas, consistent with IPCC guidelines, \n", "national GHG inventories define managed forest more broadly. On \n", "this larger area, inventories can also consider the natural response \n", "of land to human-induced environmental changes as anthropogenic, \n", "while the global model approach treats this response as part of \n", "the non-anthropogenic sink. For illustration, from 2005 to 2014, \n", "the sum of the national GHG inventories net emission estimates is \n", "0.1  ±  1.0  GtCO2 yr–1, while the mean of two global bookkeeping \n", "models is 5.1 ± 2.6 GtCO2yr–1 (likely range). {Table SPM.1}\n", "The gross emissions from AFOLU (one-third of total global \n", "emissions) are more indicative of mitigation potential of \n", "reduced deforestation than the global net emissions (13% \n", "of total global emissions), which include compensating \n", "deforestation and afforestation fluxes (high confidence). The \n", "net flux of CO2 from AFOLU is composed of two opposing gross fluxes: \n", "(i) gross emissions (20 GtCO2 yr–1) from deforestation, cultivation of \n", "soils and oxidation of wood products, and (ii) gross removals (–14 \n", "GtCO2 yr–1), largely from forest growth following wood harvest and \n", "agricultural abandonment (medium confidence). (Figure TS.4) {2.3.1}\n", "Land is a net source of CH4, accounting for 44% of anthropogenic \n", "CH4 emissions for the 2006–2017 period (medium confidence). \n", "The pause in the rise of atmospheric CH4 concentrations between \n", "2000 and 2006 and the subsequent renewed increase appear to be \n", "partially associated with land use and land use change. The recent \n", "depletion trend of the 13C isotope in the atmosphere indicates that \n", "higher biogenic sources explain part of the current CH4 increase and \n", "that biogenic sources make up a  larger proportion of the source \n", "mix than they did before 2000 (high confidence). In agreement \n", "with the findings of AR5, tropical wetlands and peatlands continue \n", "to be important drivers of inter-annual variability and current CH4 \n", "concentration increases (medium evidence, high agreement). \n", "Ruminants and the expansion of rice cultivation are also important \n", "contributors to the current trend (medium evidence, high agreement). \n", "There is significant and ongoing accumulation of CH4 in the \n", "atmosphere (very high confidence). {2.3.2}\n", "46Technical Summary\n", "TS\n", "AFOLU is the main anthropogenic source of N2O primarily due \n", "to nitrogen application to soils (high confi dence). In croplands, \n", "the main driver of N2O emissions is a lack of synchronisation between \n", "crop nitrogen demand and soil nitrogen supply, with approximately \n", "50% of the nitrogen applied to agricultural land not taken up by the \n", "crop. Cropland soils emit over 3 MtN2O-N yr–1 (medium confi dence). \n", "Because the response of N2O emissions to fertiliser application rates \n", "is non-linear, in regions of the world where low nitrogen application \n", "rates dominate, such as sub-Saharan Africa and parts of Eastern \n", "Europe, increases in nitrogen fertiliser use would generate relatively \n", "small increases in agricultural N2O emissions. Decreases in application \n", "rates in regions where application rates are high and exceed crop \n", "demand for parts of the growing season will have very large effects \n", "on emissions reductions (medium evidence, high agreement). {2.3.3}\n", "While managed pastures make up only one-quarter of \n", "grazing lands, they contributed more than three-quarters of \n", "N2O emissions from grazing lands between 1961 and 2014 \n", "with rapid recent increases of nitrogen inputs resulting \n", "in disproportionate growth in emissions from these lands \n", "(medium confi dence). Grazing lands (pastures and rangelands) \n", "are responsible for more than one-third of total anthropogenic N2O \n", "emissions or more than one-half of agricultural emissions (high \n", "confi dence). Emissions are largely from North America, Europe, \n", "East Asia, and South Asia, but hotspots are shifting from Europe to \n", "southern Asia (medium confi dence). {2.3.3}Increased emissions from vegetation and soils due to climate \n", "change in the future are expected to counteract potential sinks \n", "due to CO2 fertilisation (low confi dence). Responses of vegetation \n", "and soil organic carbon (SOC) to rising atmospheric CO2 concentration \n", "and climate change are not well constrained by observations (medium \n", "confi dence). Nutrient (e.g.,  nitrogen, phosphorus) availability can \n", "limit future plant growth and carbon storage under rising CO2 \n", "(high confi dence). However, new evidence suggests that ecosystem \n", "adaptation through plant-microbe symbioses could alleviate some \n", "nitrogen limitation (medium evidence, high agreement). Warming of \n", "soils and increased litter inputs will accelerate carbon losses through \n", "microbial respiration (high confi dence). Thawing of high latitude/\n", "altitude permafrost will increase rates of SOC loss and change the \n", "balance between CO2 and CH4 emissions (medium confi dence). The \n", "balance between increased respiration in warmer climates and \n", "carbon uptake from enhanced plant growth is a key uncertainty for \n", "the size of the future land carbon sink (medium confi dence). {2.3.1, \n", "2.7.2, Box 2.3}\n", "Biophysical and biogeochemical land forcing and feedbacks to \n", "the climate system\n", "Changes in land conditions from human use or climate change \n", "in turn affect regional and global climate (high confi dence). On \n", "the global scale, this is driven by changes in emissions or removals of \n", "CO2, CH4 and N2O by land (biogeochemical effects) and by changes \n", "in the surface albedo (very high confi dence). Any local land changes Figure TS.4 | Net and gross fl uxes of CO2 from land (annual averages for 2008–2017). Left: The total net fl ux of CO2 between land and atmosphere (grey) \n", "is shown with its two component fl uxes, (i) net AFOLU emissions (blue), and (ii) the net land sink (brown), due to indirect environmental effects and natural effects on \n", "managed and unmanaged lands. Middle: The gross emissions and removals contributing to the net AFOLU fl ux. Right: The gross emissions and removals contributing to \n", "the land sink.Total land AFOLU Indirect* land30\n", "1020\n", "–30–20–100Net land flux Gross AFOLU emissions\n", "Gross indirect removals on land Net AFOLU flux Gross AFOLU removals\n", "Net indirect flux on landGross indirect emissions on landSource Sink Gt CO 2 yr–1*indirect effects due to environmental changes on managed and unmanaged lands\n", "?\n", "?\n", "47\n", "Technical SummaryTSthat redistribute energy and water vapour between the land and \n", "the atmosphere influence regional climate (biophysical effects; \n", "high confidence). However, there is no confidence in whether such \n", "biophysical effects influence global climate. {2.1, 2.3, 2.5.1, 2.5.2}\n", "Changes in land conditions modulate the likelihood, intensity \n", "and duration of many extreme events including heatwaves \n", "(high confidence) and heavy precipitation events (medium \n", "confidence). Dry soil conditions favour or strengthen summer \n", "heatwave conditions through reduced evapotranspiration and \n", "increased sensible heat. By contrast wet soil conditions, for example \n", "from irrigation or crop management practices that maintain a cover \n", "crop all year round, can dampen extreme warm events through \n", "increased evapotranspiration and reduced sensible heat. Droughts \n", "can be intensified by poor land management. Urbanisation increases \n", "extreme rainfall events over or downwind of cities (medium \n", "confidence). {2.5.1, 2.5.2, 2.5.3}\n", "Historical changes in anthropogenic land cover have resulted \n", "in a mean annual global warming of surface air from \n", "biogeochemical effects (very high confidence), dampened \n", "by a cooling from biophysical effects (medium confidence). \n", "Biogeochemical warming results from increased emissions of GHGs \n", "by land, with model-based estimates of +0.20 ± 0.05°C (global \n", "climate models) and +0.24 ± 0.12°C – dynamic global vegetation \n", "models (DGVMs) as well as an observation-based estimate of +0.25 \n", "± 0.10°C. A net biophysical cooling of –0.10 ± 0.14°C has been \n", "derived from global climate models in response to the increased \n", "surface albedo and decreased turbulent heat fluxes, but it is smaller \n", "than the warming effect from land-based emissions. However, when \n", "both biogeochemical and biophysical effects are accounted for within \n", "the same global climate model, the models do not agree on the sign \n", "of the net change in mean annual surface air temperature. {2.3, 2.5.1, \n", "Box 2.1}\n", "The future projected changes in anthropogenic land cover that \n", "have been examined for AR5 would result in a biogeochemical \n", "warming and a biophysical cooling whose magnitudes depend \n", "on the scenario (high confidence). Biogeochemical warming has \n", "been projected for RCP8.5 by both global climate models (+0.20 ± \n", "0.15°C) and DGVMs (+0.28 ± 0.11°C) (high confidence). A global \n", "biophysical cooling of 0.10 ± 0.14°C is estimated from global climate \n", "models and is projected to dampen the land-based warming (low \n", "confidence). For RCP4.5, the biogeochemical warming estimated \n", "from global climate models (+0.12 ± 0.17°C) is stronger than the \n", "warming estimated by DGVMs (+0.01 ± 0.04°C) but based on limited \n", "evidence, as is the biophysical cooling (–0.10 ± 0.21°C). {2.5.2}\n", "Regional climate change can be dampened or enhanced by \n", "changes in local land cover and land use (high confidence) \n", "but this depends on the location and the season (high \n", "confidence). In boreal regions, for example, where projected climate \n", "change will migrate the treeline northward, increase the growing \n", "season length and thaw permafrost, regional winter warming will \n", "be enhanced by decreased surface albedo and snow, whereas \n", "warming will be dampened during the growing season due to larger \n", "evapotranspiration (high confidence). In the tropics, wherever climate change will increase rainfall, vegetation growth and associated \n", "increase in evapotranspiration will result in a dampening effect on \n", "regional warming (medium confidence). {2.5.2, 2.5.3}\n", "According to model-based studies, changes in local land \n", "cover or available water from irrigation will affect climate in \n", "regions as far as few hundreds of kilometres downwind (high \n", "confidence). The local redistribution of water and energy following \n", "the changes on land affect the horizontal and vertical gradients of \n", "temperature, pressure and moisture, thus altering regional winds and \n", "consequently moisture and temperature advection and convection \n", "and subsequently, precipitation. {2.5.2, 2.5.4, Cross-Chapter Box 4 \n", "in Chapter 2}\n", "Future increases in both climate change and urbanisation will \n", "enhance warming in cities and their surroundings (urban heat \n", "island), especially during heatwaves (high confidence). Urban \n", "and peri-urban agriculture, and more generally urban greening, can \n", "contribute to mitigation (medium confidence) as well as to adaptation \n", "(high confidence), with co-benefits for food security and reduced soil-\n", "water-air pollution. {Cross-Chapter Box 4 in Chapter 2}\n", "Regional climate is strongly affected by natural land aerosols \n", "(medium confidence) (e.g., mineral dust, black, brown and \n", "organic carbon), but there is low confidence in historical trends, \n", "inter-annual and decadal variability and future changes. Forest \n", "cover affects climate through emissions of biogenic volatile organic \n", "compounds (BVOC) and aerosols (low confidence). The decrease \n", "in the emissions of BVOC resulting from the historical conversion \n", "of forests to cropland has resulted in a positive radiative forcing \n", "through direct and indirect aerosol effects, a negative radiative \n", "forcing through the reduction in the atmospheric lifetime of methane \n", "and it has contributed to increased ozone concentrations in different \n", "regions (low confidence). {2.4, 2.5}\n", "Consequences for the climate system of land-based adaptation \n", "and mitigation options, including carbon dioxide removal \n", "(negative emissions)\n", "About one-quarter of the 2030 mitigation pledged by countries \n", "in their initial Nationally Determined Contributions (NDCs) \n", "under the Paris Agreement is expected to come from land-\n", "based mitigation options (medium confidence). Most of the \n", "NDCs submitted by countries include land-based mitigation, although \n", "many lack details. Several refer explicitly to reduced deforestation \n", "and forest sinks, while a few include soil carbon sequestration, \n", "agricultural management and bioenergy. Full implementation of \n", "NDCs (submitted by February 2016) is expected to result in net \n", "removals of 0.4–1.3 GtCO2 y–1 in 2030 compared to the net flux in \n", "2010, where the range represents low to high mitigation ambition \n", "in pledges, not uncertainty in estimates (medium confidence). {2.6.3}\n", "48Technical Summary\n", "TS\n", "Figure TS.5 | Mitigation potential of response options in 2020–2050, measured in GtCO2-eq yr–1, adapted from Roe et al. (2017).DEMAND MANAGEMENTLAND MANAGEMENT\n", "Waste and Losses\n", "Reduce food and agricultural waste\n", "Diets\n", "Shift to plant-based diets \n", "Wood Products\n", "Increase substitution of cement/steel \n", "Wood Fuel\n", "Increase cleaner cookstovesReduce deforestation \n", "Reduce forest degradation \n", "Reduce conversion, draining, \n", "burning of peatlands\n", "Reduce conversion of coastal wetlands \n", "(mangroves, seagrass and marshes)\n", "Reduce conversion of savannas \n", "and natural grasslands\n", "Afforestation/Reforestation (A/R)\n", "Forest management\n", "Agroforestry\n", "Peatland restoration\n", "Coastal wetland restoration\n", "Soil carbon sequestration in croplands \n", "Soil carbon sequestration in grazing lands\n", "Biochar application\n", "BECCS deploymentCropland nutrient management N 2O\n", "Reduced N 2O from manure on pasture \n", "Manure management N 2O and CH 4\n", "Improved rice cultivation CH 4\n", "Reduced enteric fermentation CH 4\n", "Improved synthetic fertilizer production\n", "2 4 6 8 0 10\n", "2 4 6 8 0 10Mitigation potential (GtCO 2-eq yr–1)\n", "Mitigation potential (GtCO 2-eq yr–1)Reduce emissions from Forests and other Ecosystems \n", "Carbon Dioxide RemovalReduce emissions from Agriculture \n", "1–5\n", "6\n", "5, 7\n", "1–5, 8\n", "2, 5, 51References\n", "2, 5, 7, 18, 51–54\n", "29, 55\n", "1, 2, 561, 5, 7, 9\n", "5, 10\n", "1, 2, 11, 18\n", "13, 16, 19\n", "1, 2, 20\n", "1, 2, 21, 22\n", "1\n", "1, 31, 32\n", "23, 28–30, 45, 49, 501, 2, 5, 33\n", "1, 34\n", "1\n", "1, 2, 40, 3, 5, 7, 35–39\n", "1, 2, 43, 44, 3, 29, 36, 37, 39–42\n", "1, 2, 47, 48, 3, 5, 23, 28, 30, 42, 45, 461, 2, 29, 30, 11, 15, 23–28\n", "13.5015.57\n", "0.76–4.5\n", "0.70–8\n", "0.25–10.41–5.80\n", "1–2.18\n", "0.45–1.22\n", "0.11–2.25\n", "0.03–0.12\n", "0.10–0.810.44–2.10\n", "0.11–5.68\n", "0.15–0.81\n", "0.20–0.84\n", "0.25–6.78\n", "0.13–2.56\n", "0.03–6.60\n", "0.4040–11.300.03–0.71\n", "0.01\n", "0.01–0.26\n", "0.08–0.87\n", "0.12–1.18\n", "0.05–0.36\n", "0.50–10.12SUSTAINABLE POTENTIALECONOMIC POTENTIALTECHNICAL POTENTIAL\n", "INTERMODEL RANGE 1.5ºC\n", "INTERMODEL RANGE 2ºCMEDIAN\n", "49\n", "Technical SummaryTSSeveral mitigation response options have technical potential \n", "for >3 GtCO2-eq yr–1 by 2050 through reduced emissions and \n", "Carbon Dioxide Removal (CDR) (high confidence), some of \n", "which compete for land and other resources, while others \n", "may reduce the demand for land (high confidence). Estimates \n", "of the technical potential of individual response options are not \n", "necessarily additive. The largest potential for reducing AFOLU \n", "emissions are through reduced deforestation and forest degradation \n", "(0.4–5.8 GtCO2-eq yr–1) (high confidence), a shift towards plant-\n", "based diets (0.7–8.0 GtCO2-eq yr–1) (high confidence) and reduced \n", "food and agricultural waste (0.8–4.5 CO2-eq yr–1) (high confidence). \n", "Agriculture measures combined could mitigate 0.3–3.4 GtCO2-eq yr–1 \n", "(medium confidence). The options with largest potential for CDR \n", "are afforestation/reforestation (0.5–10.1 CO2-eq yr–1) (medium \n", "confidence), soil carbon sequestration in croplands and grasslands \n", "(0.4–8.6 CO2-eq yr–1) (high confidence) and Bioenergy with Carbon \n", "Capture and Storage (BECCS) (0.4–11.3 CO2-eq yr–1) (medium \n", "confidence). While some estimates include sustainability and cost \n", "considerations, most do not include socio-economic barriers, the \n", "impacts of future climate change or non-GHG climate forcings. {2.6.1}\n", "Response options intended to mitigate global warming \n", "will also affect the climate locally and regionally through \n", "biophysical effects (high confidence). Expansion of forest area, \n", "for example, typically removes CO2 from the atmosphere and thus \n", "dampens global warming (biogeochemical effect, high confidence), \n", "but the biophysical effects can dampen or enhance regional warming \n", "depending on location, season and time of day. During the growing \n", "season, afforestation generally brings cooler days from increased \n", "evapotranspiration, and warmer nights (high confidence). During \n", "the dormant season, forests are warmer than any other land cover, \n", "especially in snow-covered areas where forest cover reduces albedo \n", "(high confidence). At the global level, the temperature effects of \n", "boreal afforestation/reforestation run counter to GHG effects, while \n", "in the tropics they enhance GHG effects. In addition, trees locally \n", "dampen the amplitude of heat extremes (medium confidence). {2.5.2, \n", "2.5.4, 2.7, Cross-Chapter Box 4 in Chapter 2}\n", "Mitigation response options related to land use are a key \n", "element of most modelled scenarios that provide strong \n", "mitigation, alongside emissions reduction in other sectors \n", "(high confidence). More stringent climate targets rely more \n", "heavily on land-based mitigation options, in particular, CDR \n", "(high confidence). Across a range of scenarios in 2100, CDR is \n", "delivered by both afforestation (median values of –1.3, –1.7 and –2.4 \n", "GtCO2yr–1 for scenarios RCP4.5, RCP2.6 and RCP1.9 respectively) and \n", "BECCS (–6.5, –11 and –14.9 GtCO2 yr–1 respectively). Emissions of CH4 and N2O are reduced through improved agricultural and livestock \n", "management as well as dietary shifts away from emission-intensive \n", "livestock products by 133.2, 108.4 and 73.5 MtCH4 yr–1; and 7.4, \n", "6.1 and 4.5 MtN2O yr–1 for the same set of scenarios in 2100 (high \n", "confidence). High levels of bioenergy crop production can result \n", "in increased N2O emissions due to fertiliser use. The Integrated \n", "Assessment Models that produce these scenarios mostly neglect \n", "the biophysical effects of land-use on global and regional warming. \n", "{2.5, 2.6.2}\n", "Large-scale implementation of mitigation response options \n", "that limit warming to 1.5 or 2°C would require conversion \n", "of large areas of land for afforestation/reforestation and \n", "bioenergy crops, which could lead to short-term carbon losses \n", "(high confidence). The change of global forest area in mitigation \n", "pathways ranges from about –0.2 to +7.2 Mkm2 between 2010 \n", "and 2100 (median values across a range of models and scenarios: \n", "RCP4.5, RCP2.6, RCP1.9), and the land demand for bioenergy crops \n", "ranges from about 3.2 to 6.6 Mkm2 in 2100 (high confidence). Large-\n", "scale land-based CDR is associated with multiple feasibility and \n", "sustainability constraints. In high carbon lands such as forests and \n", "peatlands, the carbon benefits of land protection are greater in the \n", "short-term than converting land to bioenergy crops for BECCS, which \n", "can take several harvest cycles to ‘pay-back’ the carbon emitted \n", "during conversion (carbon-debt), from decades to over a century \n", "(medium confidence). (Figure TS.5) {2.6.2, Chapters 6, 7}\n", "It is possible to achieve climate change targets with low need \n", "for land-demanding CDR such as BECCS, but such scenarios \n", "rely more on rapidly reduced emissions or CDR from forests, \n", "agriculture and other sectors. Terrestrial CDR has the technical \n", "potential to balance emissions that are difficult to eliminate \n", "with current technologies (including food production). Scenarios \n", "that achieve climate change targets with less need for terrestrial \n", "CDR rely on agricultural demand-side changes (diet change, \n", "waste reduction), and changes in agricultural production such as \n", "agricultural intensification. Such pathways that minimise land use for \n", "bioenergy and BECCS are characterised by rapid and early reduction \n", "of GHG emissions in all sectors, as well as earlier CDR in through \n", "afforestation. In contrast, delayed mitigation action would increase \n", "reliance on land-based CDR (high confidence). {2.6.2}Figure TS.5 (continued): Mitigation potentials reflect the full range of low to high estimates from studies published after 2010, differentiated according to technical \n", "(possible with current technologies), economic (possible given economic constraints) and sustainable potential (technical or economic potential constrained by \n", "sustainability considerations). Medians are calculated across all potentials in categories with more than four data points. We only include references that explicitly \n", "provide mitigation potential estimates in CO2-eq yr–1 (or a similar derivative) by 2050. Not all options for land management potentials are additive, as some may \n", "compete for land. Estimates reflect a range of methodologies (including definitions, global warming potentials and time horizons) that may not be directly comparable \n", "or additive. Results from IAMs are shown to compare with single option ‘bottom-up’ estimates, in available categories from the 2°C and 1.5°C scenarios in the SSP \n", "Database (version 2.0). The models reflect land management changes, yet in some instances, can also reflect demand-side effects from carbon prices, so may not be \n", "defined exclusively as ‘supply-side’.\n", "50\n", "Technical Summary\n", "TSTS.3 Desertification\n", "Desertification is land degradation in arid, semi-arid, and dry \n", "sub-humid areas, collectively known as drylands, resulting \n", "from many factors, including human activities and climatic \n", "variations. The range and intensity of desertification have \n", "increased in some dryland areas over the past several decades \n", "(high confidence). Drylands currently cover about 46.2% (±0.8%) \n", "of the global land area and are home to 3 billion people. The \n", "multiplicity and complexity of the processes of desertification make \n", "its quantification difficult. Desertification hotspots, as identified by \n", "a decline in vegetation productivity between the 1980s and 2000s, \n", "extended to about 9.2% of drylands (±0.5%), affecting about 500 \n", "(±120) million people in 2015. The highest numbers of people affected \n", "are in South and East Asia, the circum Sahara region including \n", "North Africa and the Middle East including the Arabian Peninsula \n", "(low confidence). Other dryland regions have also experienced \n", "desertification. Desertification has already reduced agricultural \n", "productivity and incomes (high confidence) and contributed to the \n", "loss of biodiversity in some dryland regions (medium confidence). \n", "In many dryland areas, spread of invasive plants has led to losses \n", "in ecosystem services (high confidence), while over-extraction is \n", "leading to groundwater depletion (high confidence). Unsustainable \n", "land management, particularly when coupled with droughts, has \n", "contributed to higher dust-storm activity, reducing human well-\n", "being in drylands and beyond (high confidence). Dust storms were \n", "associated with global cardiopulmonary mortality of about 402,000 \n", "people in 2005. Higher intensity of sand storms and sand dune \n", "movements are causing disruption and damage to transportation and \n", "solar and wind energy harvesting infrastructures (high confidence). \n", "(Figure TS.6) {3.1.1, 3.1.4, 3.2.1, 3.3.1, 3.4.1, 3.4.2, 3.4.2, 3.7.3, 3.7.4}\n", "Attribution of desertification to climate variability and \n", "change, and to human activities, varies in space and time (high \n", "confidence). Climate variability and anthropogenic climate change, \n", "particularly through increases in both land surface air temperature \n", "and evapotranspiration, and decreases in precipitation, are likely to \n", "have played a role, in interaction with human activities, in causing \n", "desertification in some dryland areas. The major human drivers of \n", "desertification interacting with climate change are expansion of \n", "croplands, unsustainable land management practices and increased \n", "pressure on land from population and income growth. Poverty is \n", "limiting both capacities to adapt to climate change and availability of \n", "financial resources to invest in sustainable land management (SLM) \n", "(high confidence). {3.1.4, 3.2.2, 3.4.2}\n", "Climate change will exacerbate several desertification \n", "processes (medium confidence). Although CO2 fertilisation effect \n", "is enhancing vegetation productivity in drylands (high confidence), \n", "decreases in water availability have a larger effect than CO2 \n", "fertilisation in many dryland areas. There is high confidence that \n", "aridity will increase in some places, but no evidence for a projected \n", "global trend in dryland aridity (medium confidence). The area at risk \n", "of salinisation is projected to increase in the future (limited evidence, \n", "high agreement). Future climate change is projected to increase the \n", "potential for water driven soil erosion in many dryland areas (medium confidence), leading to soil organic carbon decline in some dryland \n", "areas. {3.1.1, 3.2.2, 3.5.1, 3.5.2, 3.7.1, 3.7.3}\n", "Risks from desertification are projected to increase due to \n", "climate change (high confidence). Under shared socio-economic \n", "pathway SSP2 (‘Middle of the Road’) at 1.5°C, 2°C and 3°C of global \n", "warming, the number of dryland population exposed (vulnerable) \n", "to various impacts related to water, energy and land sectors (e.g. \n", "water stress, drought intensity, habitat degradation) is projected \n", "to reach 951 (178) million, 1152 (220) million and 1285 (277) \n", "million, respectively. While at global warming of 2°C, under SSP1 \n", "(‘Sustainability’), the exposed (vulnerable) dryland population is 974 \n", "(35) million, and under SSP3 (‘Fragmented World’) it is 1267 (522) \n", "million. Around half of the vulnerable population is in South Asia, \n", "followed by Central Asia, West Africa and East Asia. {2.2, 3.1.1, 3.2.2, \n", "3.5.1, 3.5.2, 7.2.2} \n", "Desertification and climate change, both individually and in \n", "combination, will reduce the provision of dryland ecosystem \n", "services and lower ecosystem health, including losses in \n", "biodiversity (high confidence). Desertification and changing \n", "climate are projected to cause reductions in crop and livestock \n", "productivity (high confidence), modify the composition of plant \n", "species and reduce biological diversity across drylands (medium \n", "confidence). Rising CO2 levels will favour more rapid expansion of \n", "some invasive plant species in some regions. A reduction in the \n", "quality and quantity of resources available to herbivores can have \n", "knock-on consequences for predators, which can potentially lead to \n", "disruptive ecological cascades (limited evidence, low agreement). \n", "Projected increases in temperature and the severity of drought \n", "events across some dryland areas can increase chances of wildfire \n", "occurrence (medium confidence). {3.1.4, 3.4.1, 3.5.2, 3.7.3}\n", "Increasing human pressures on land, combined with climate \n", "change, will reduce the resilience of dryland populations and \n", "constrain their adaptive capacities (medium confidence). \n", "The combination of pressures coming from climate variability, \n", "anthropogenic climate change and desertification will contribute \n", "to poverty, food insecurity, and increased disease burden (high \n", "confidence), as well as potentially to conflicts (low confidence). \n", "Although strong impacts of climate change on migration in dryland \n", "areas are disputed (medium evidence, low agreement), in some \n", "places, desertification under changing climate can provide an added \n", "incentive to migrate (medium confidence). Women will be impacted \n", "more than men by environmental degradation, particularly in those \n", "areas with higher dependence on agricultural livelihoods (medium \n", "evidence, high agreement). {3.4.2, 3.6.2}\n", "Desertification exacerbates climate change through several \n", "mechanisms such as changes in vegetation cover, sand and \n", "dust aerosols and greenhouse gas fluxes (high confidence). \n", "The extent of areas in which dryness (rather than temperature) \n", "controls CO2 exchange has increased by 6% between 1948 and \n", "2012, and is projected to increase by at least another 8% by \n", "2050 if the expansion continues at the same rate. In these \n", "areas, net carbon uptake is about 27% lower than in other \n", "areas (low confidence). Desertification also tends to increase \n", "51Technical Summary\n", "TS\n", "albedo, decreasing the energy available at the surface and associated \n", "surface temperatures, producing a negative feedback on climate \n", "change (high confi dence). Through its effect on vegetation and soils, \n", "desertifi cation changes the absorption and release of associated \n", "greenhouse gases (GHGs). Vegetation loss and drying of surface \n", "cover due to desertifi cation increases the frequency of dust storms \n", "(high confi dence). Arid ecosystems could be an important global \n", "carbon sink, depending on soil water availability (medium evidence, \n", "high agreement). {3.3.3, 3.4.1, 3.5.2}\n", "Site and regionally-specifi c technological solutions, based \n", "both on new scientifi c innovations and indigenous and local \n", "knowledge (ILK), are available to avoid, reduce and reverse \n", "desertifi cation, simultaneously contributing to climate change \n", "mitigation and adaptation (high confi dence). SLM practices in \n", "drylands increase agricultural productivity and contribute to climate \n", "change adaptation with mitigation co-benefi ts (high confi dence). \n", "Integrated crop, soil and water management measures can be \n", "employed to reduce soil degradation and increase the resilience of \n", "agricultural production systems to the impacts of climate change \n", "(high confi dence). These measures include crop diversifi cation \n", "and adoption of drought-resilient econogically appropriate plants, \n", "reduced tillage, adoption of improved irrigation techniques (e.g. \n", "drip irrigation) and moisture conservation methods (e.g. rainwater \n", "harvesting using indigenous and local practices), and maintaining \n", "vegetation and mulch cover. Conservation agriculture increases the \n", "capacity of agricultural households to adapt to climate change (high \n", "confi dence) and can lead to increases in soil organic carbon over time, \n", "with quantitative estimates of the rates of carbon sequestration in \n", "drylands following changes in agricultural practices ranging between \n", "0.04 and 0.4 t ha–1 (medium confi dence). Rangeland management \n", "systems based on sustainable grazing and re-vegetation increase \n", "rangeland productivity and the fl ow of ecosystem services (high \n", "confi dence). The combined use of salt-tolerant crops, improved \n", "irrigation practices, chemical remediation measures and appropriate mulch and compost is effective in reducing the impact of secondary \n", "salinisation (medium confi dence). Application of sand dune \n", "stabilisation techniques contributes to reducing sand and dust storms \n", "(high confi dence). Agroforestry practices and shelterbelts help reduce \n", "soil erosion and sequester carbon. Afforestation programmes aimed \n", "at creating windbreaks in the form of ‘green walls’ and ‘green dams’ \n", "can help stabilise and reduce dust storms, avert wind erosion, and \n", "serve as carbon sinks, particularly when done with locally adapted \n", "native and other climate resilient tree species (high confi dence). \n", "{3.4.2, 3.6.1, 3.7.2}\n", "Investments into SLM, land restoration and rehabilitation in \n", "dryland areas have positive economic returns (high confi dence). \n", "Each USD invested into land restoration can have social returns \n", "of about 3–6 USD over a 30-year period. Most SLM practices can \n", "become fi nancially profi table within 3 to 10 years (medium evidence, \n", "high agreement). Despite their benefi ts in addressing desertifi cation, \n", "mitigating and adapting to climate change, and increasing food \n", "and economic security, many SLM practices are not widely adopted \n", "due to insecure land tenure, lack of access to credit and agricultural \n", "advisory services, and insuffi cient incentives for private land-users \n", "(robust evidence, high agreement). {3.6.3}\n", "Indigenous and local knowledge often contributes to \n", "enhancing resilience against climate change and combating \n", "desertifi cation (medium confi dence). Dryland populations \n", "have developed traditional agroecological practices which are well \n", "adapted to resource-sparse dryland environments. However, there \n", "is robust evidence documenting losses of traditional agroecological \n", "knowledge. Traditional agroecological practices are also increasingly \n", "unable to cope with growing demand for food. Combined use of ILK \n", "and new SLM technologies can contribute to raising the resilience \n", "to the challenges of climate change and desertifi cation (high \n", "confi dence). {3.1.3, 3.6.1, 3.6.2}Figure TS.6 | Geographical distribution of drylands, delimited based on the aridity index (AI). The classifi cation of AI is: Humid AI > 0.65, Dry sub-humid \n", "0.50 < AI ≤ 0.65, Semi-arid 0.20 < AI ≤ 0.50, Arid 0.05 < AI ≤ 0.20, Hyper-arid AI < 0.05. Data: TerraClimate precipitation and potential evapotranspiration (1980–2015) \n", "(Abatzoglou et al. 2018).\n", "\n", "52\n", "Technical Summary\n", "TSPolicy frameworks promoting the adoption of SLM solutions \n", "contribute to addressing desertification as well as mitigating \n", "and adapting to climate change, with co-benefits for poverty \n", "eradication and food security among dryland populations (high \n", "confidence). Implementation of Land Degradation Neutrality \n", "(LDN) policies allows populations to avoid, reduce and reverse \n", "desertification, thus contributing to climate change adaptation \n", "with mitigation co-benefits (high confidence). Strengthening land \n", "tenure security is a major factor contributing to the adoption of soil \n", "conservation measures in croplands (high confidence). On-farm and \n", "off-farm livelihood diversification strategies increase the resilience of \n", "rural households against desertification and extreme weather events, \n", "such as droughts (high confidence). Strengthening collective action \n", "is important for addressing causes and impacts of desertification, \n", "and for adapting to climate change (medium confidence). A greater \n", "emphasis on understanding gender-specific differences over land \n", "use and land management practices can help make land restoration \n", "projects more successful (medium confidence). Improved access to \n", "markets raises agricultural profitability and motivates investment into \n", "climate change adaptation and SLM (medium confidence). Payments \n", "for ecosystem services give additional incentives to land users to \n", "adopt SLM practices (medium confidence). Expanding access to rural \n", "advisory services increases the knowledge on SLM and facilitates \n", "their wider adoption (medium confidence). Developing, enabling \n", "and promoting access to cleaner energy sources and technologies \n", "can contribute to reducing desertification and mitigating climate \n", "change through decreasing the use of fuelwood and crop residues \n", "for energy (medium confidence). Policy responses to droughts based \n", "on proactive drought preparedness and drought risk mitigation are \n", "more efficient in limiting drought-caused damages than reactive \n", "drought relief efforts (high confidence). {3.4.2, 3.6.2, 3.6.3, Cross-\n", "Chapter Box 5 in Chapter 3}The knowledge on limits of adaptation to the combined \n", "effects of climate change and desertification is insufficient. \n", "However, the potential for residual risks and maladaptive \n", "outcomes is high (high confidence). Empirical evidence on the \n", "limits to adaptation in dryland areas is limited. Potential limits to \n", "adaptation include losses of land productivity due to irreversible \n", "forms of desertification. Residual risks can emerge from the \n", "inability of SLM measures to fully compensate for yield losses due \n", "to climate change impacts. They also arise from foregone reductions \n", "in ecosystem services due to soil fertility loss even when applying \n", "SLM measures could revert land to initial productivity after some \n", "time. Some activities favouring agricultural intensification in dryland \n", "areas can become maladaptive due to their negative impacts on the \n", "environment (medium confidence) Even when solutions are available, \n", "social, economic and institutional constraints could pose barriers to \n", "their implementation (medium confidence) {3.6.4}. \n", "Improving capacities, providing higher access to climate \n", "services, including local-level early warning systems, and \n", "expanding the use of remote sensing technologies are high-\n", "return investments for enabling effective adaptation and \n", "mitigation responses that help address desertification (high \n", "confidence). Reliable and timely climate services, relevant to \n", "desertification, can aid the development of appropriate adaptation \n", "and mitigation options reducing, the impact of desertification on \n", "human and natural systems (high confidence), with quantitative \n", "estimates showing that every USD invested in strengthening hydro-\n", "meteorological and early warning services in developing countries \n", "can yield between 4 and 35 USD (low confidence). Knowledge \n", "and flow of knowledge on desertification is currently fragmented. \n", "Improved knowledge and data exchange and sharing will increase the \n", "effectiveness of efforts to achieve LDN (high confidence). Expanded \n", "use of remotely sensed information for data collection helps in \n", "measuring progress towards achieving LDN (low evidence, high \n", "agreement). {3.2.1, 3.6.2, 3.6.3, Cross-Chapter Box 5 in Chapter 3}\n", "53\n", "Technical SummaryTSTS.4 Land degradation \n", "Land degradation affects people and ecosystems throughout \n", "the planet and is both affected by climate change and \n", "contributes to it. In this report, land degradation is defined as \n", "a negative trend in land condition, caused by direct or indirect \n", "human-induced processes including anthropogenic climate change, \n", "expressed as long-term reduction or loss of at least one of the \n", "following: biological productivity, ecological integrity, or value to \n", "humans. Forest degradation is land degradation that occurs in forest \n", "land. Deforestation is the conversion of forest to non-forest land and \n", "can result in land degradation. {4.1.3}\n", "Land degradation adversely affects people’s livelihoods (very \n", "high confidence) and occurs over a quarter of the Earth’s \n", "ice-free land area (medium confidence). The majority of the \n", "1.3 to 3.2 billion affected people (low confidence) are living \n", "in poverty in developing countries (medium confidence). \n", "Land-use changes and unsustainable land management are direct \n", "human causes of land degradation (very high confidence), with \n", "agriculture being a dominant sector driving degradation (very high \n", "confidence). Soil loss from conventionally tilled land exceeds the rate \n", "of soil formation by >2 orders of magnitude (medium confidence). \n", "Land degradation affects humans in multiple ways, interacting \n", "with social, political, cultural and economic aspects, including \n", "markets, technology, inequality and demographic change (very high \n", "confidence). Land degradation impacts extend beyond the land \n", "surface itself, affecting marine and freshwater systems, as well as \n", "people and ecosystems far away from the local sites of degradation \n", "(very high confidence). {4.1.6, 4.2.1, 4.2.3, 4.3, 4.6.1, 4.7, Table 4.1} \n", "Climate change exacerbates the rate and magnitude of \n", "several ongoing land degradation processes and introduces \n", "new degradation patterns (high confidence). Human-induced \n", "global warming has already caused observed changes in two drivers \n", "of land degradation: increased frequency, intensity and/or amount \n", "of heavy precipitation (medium confidence); and increased heat \n", "stress (high confidence). In some areas sea level rise has exacerbated \n", "coastal erosion (medium confidence). Global warming beyond \n", "present day will further exacerbate ongoing land degradation \n", "processes through increasing floods (medium confidence), drought \n", "frequency and severity (medium confidence), intensified cyclones \n", "(medium confidence), and sea level rise (very high confidence), \n", "with outcomes being modulated by land management (very high \n", "confidence). Permafrost thawing due to warming (high confidence), \n", "and coastal erosion due to sea level rise and impacts of changing \n", "storm paths (low confidence), are examples of land degradation \n", "affecting places where it has not typically been a problem. Erosion of \n", "coastal areas because of sea level rise will increase worldwide (high \n", "confidence). In cyclone prone areas, the combination of sea level rise \n", "and more intense cyclones will cause land degradation with serious \n", "consequences for people and livelihoods (very high confidence). \n", "{4.2.1, 4.2.2, 4.2.3, 4.4.1, 4.4.2, 4.9.6, Table 4.1} \n", "Land degradation and climate change, both individually \n", "and in combination, have profound implications for natural \n", "resource-based livelihood systems and societal groups (high confidence). The number of people whose livelihood depends on \n", "degraded lands has been estimated to be about 1.5 billion worldwide \n", "(very low confidence). People in degraded areas who directly depend \n", "on natural resources for subsistence, food security and income, \n", "including women and youth with limited adaptation options, are \n", "especially vulnerable to land degradation and climate change \n", "(high confidence). Land degradation reduces land productivity and \n", "increases the workload of managing the land, affecting women \n", "disproportionally in some regions. Land degradation and climate \n", "change act as threat multipliers for already precarious livelihoods \n", "(very high confidence), leaving them highly sensitive to extreme \n", "climatic events, with consequences such as poverty and food \n", "insecurity (high confidence) and, in some cases, migration, conflict \n", "and loss of cultural heritage (low confidence). Changes in vegetation \n", "cover and distribution due to climate change increase the risk of land \n", "degradation in some areas (medium confidence). Climate change will \n", "have detrimental effects on livelihoods, habitats and infrastructure \n", "through increased rates of land degradation (high confidence) and \n", "from new degradation patterns (low evidence, high agreement). \n", "{4.1.6, 4.2.1, 4.7} \n", "Land degradation is a driver of climate change through \n", "emission of greenhouse gases (GHGs) and reduced rates of \n", "carbon uptake (very high confidence). Since 1990, globally the \n", "forest area has decreased by 3% (low confidence) with net decreases \n", "in the tropics and net increases outside the tropics (high confidence). \n", "Lower carbon density in re-growing forests compared, to carbon \n", "stocks before deforestation, results in net emissions from land-use \n", "change (very high confidence). Forest management that reduces \n", "carbon stocks of forest land also leads to emissions, but global \n", "estimates of these emissions are uncertain. Cropland soils have \n", "lost 20–60% of their organic carbon content prior to cultivation, \n", "and soils under conventional agriculture continue to be a source \n", "of GHGs (medium confidence). Of the land degradation processes, \n", "deforestation, increasing wildfires, degradation of peat soils, and \n", "permafrost thawing contribute most to climate change through the \n", "release of GHGs and the reduction in land carbon sinks following \n", "deforestation (high confidence). Agricultural practices also emit non-\n", "CO2 GHGs from soils and these emissions are exacerbated by climate \n", "change (medium confidence). Conversion of primary to managed \n", "forests, illegal logging and unsustainable forest management result \n", "in GHG emissions (very high confidence) and can have additional \n", "physical effects on the regional climate including those arising from \n", "albedo shifts (medium confidence). These interactions call for more \n", "integrative climate impact assessments. {4.2.2, 4.3, 4.5.4, 4.6}\n", "Large-scale implementation of dedicated biomass production \n", "for bioenergy increases competition for land with potentially \n", "serious consequences for food security and land degradation \n", "(high confidence). Increasing the extent and intensity of biomass \n", "production, for example, through fertiliser additions, irrigation or \n", "monoculture energy plantations, can result in local land degradation. \n", "Poorly implemented intensification of land management contributes \n", "to land degradation (e.g., salinisation from irrigation) and disrupted \n", "livelihoods (high confidence). In areas where afforestation and \n", "reforestation occur on previously degraded lands, opportunities \n", "exist to restore and rehabilitate lands with potentially significant \n", "54Technical Summary\n", "TSco-benefi ts (high confi dence) that depend on whether restoration \n", "involves natural or plantation forests. The total area of degraded \n", "lands has been estimated at 10–60 Mkm2 (very low confi dence). The \n", "extent of degraded and marginal lands suitable for dedicated biomass \n", "production is highly uncertain and cannot be established without \n", "due consideration of current land use and land tenure. Increasing \n", "the area of dedicated energy crops can lead to land degradation \n", "elsewhere through indirect land-use change (medium confi dence). \n", "Impacts of energy crops can be reduced through strategic integration \n", "with agricultural and forestry systems (high confi dence) but the \n", "total quantity of biomass that can be produced through synergistic \n", "production systems is unknown. {4.1.6, 4.4.2, 4.5, 4.7.1, 4.8.1, 4.8.3, \n", "4.8.4, 4.9.3} Reducing unsustainable use of traditional biomass reduces \n", "land degradation and emissions of CO2 while providing social \n", "and economic co-benefi ts (very high confi dence). Traditional \n", "biomass in the form of fuelwood, charcoal and agricultural residues \n", "remains a primary source of energy for more than one-third of \n", "the global population, leading to unsustainable use of biomass \n", "resources and forest degradation and contributing around 2% of \n", "global GHG emissions (low confi dence). Enhanced forest protection, \n", "improved forest and agricultural management, fuel-switching and \n", "adoption of effi cient cooking and heating appliances can promote \n", "more sustainable biomass use and reduce land degradation, with \n", "co-benefi ts of reduced GHG emissions, improved human health, \n", "and reduced workload especially for women and youth (very high \n", "confi dence). {4.1.6, 4.5.4} \n", "Figure TS.7 | Conceptual fi gure illustrating that climate change impacts interact with land management to determine sustainable or degraded \n", "outcome. Climate change can exacerbate many degradation processes (Table 4.1) and introduce novel ones (e.g., permafrost thawing or biome shifts), hence management \n", "needs to respond to climate impacts in order to avoid, reduce or reverse degradation. The types and intensity of human land-use and climate change impacts on lands affect \n", "their carbon stocks and their ability to operate as carbon sinks. In managed agricultural lands, degradation typically results in reductions of soil organic carbon stocks, which \n", "also adversely affects land productivity and carbon sinks. In forest land, reduction in biomass carbon stocks alone is not necessarily an indication of a reduction in carbon \n", "sinks. Sustainably managed forest landscapes can have a lower biomass carbon density but the younger forests can have a higher growth rate, and therefore contribute \n", "stronger carbon sinks, than older forests. Ranges of carbon sinks in forest and agricultural lands are overlapping. In some cases, climate change impacts may result in \n", "increased productivity and carbon stocks, at least in the short term.Land management options\n", "Unsustainable land management Sustainable land management\n", "Sustainably managed land Degraded land\n", "Net carbon uptake\n", "SourceSinkForest\n", "Agriculture\n", "Forest\n", "AgricultureRestoration and rehabilitation\n", "DegradationClimate change\n", "Carbon stock\n", "+\n", "–\n", "More degraded Less degraded\n", "55\n", "Technical SummaryTS\n", "Land degradation can be avoided, reduced or reversed by \n", "implementing sustainable land management, restoration \n", "and rehabilitation practices that simultaneously provide \n", "many co-benefits, including adaptation to and mitigation of \n", "climate change (high confidence). Sustainable land management \n", "involves a comprehensive array of technologies and enabling \n", "conditions, which have proven to address land degradation at \n", "multiple landscape scales, from local farms (very high confidence) \n", "to entire watersheds (medium confidence). Sustainable forest \n", "management can prevent deforestation, maintain and enhance \n", "carbon sinks and can contribute towards GHG emissions-reduction \n", "goals. Sustainable forest management generates socio-economic \n", "benefits, and provides fibre, timber and biomass to meet society’s \n", "growing needs. While sustainable forest management sustains high \n", "carbon sinks, the conversion from primary forests to sustainably \n", "managed forests can result in carbon emission during the transition \n", "and loss of biodiversity (high confidence). Conversely, in areas of degraded forests, sustainable forest management can increase \n", "carbon stocks and biodiversity (medium confidence). Carbon storage \n", "in long-lived wood products and reductions of emissions from use of \n", "wood products to substitute for emissions-intensive materials also \n", "contribute to mitigation objectives. (Figure TS.8) {4.8, 4.9, Table 4.2}\n", "Lack of action to address land degradation will increase \n", "emissions and reduce carbon sinks and is inconsistent with \n", "the emissions reductions required to limit global warming \n", "to 1.5°C or 2°C. (high confidence). Better management of soils \n", "can offset 5–20% of current global anthropogenic GHG emissions \n", "(medium confidence). Measures to avoid, reduce and reverse land \n", "degradation are available but economic, political, institutional, legal \n", "and socio-cultural barriers, including lack of access to resources \n", "and knowledge, restrict their uptake (very high confidence). Proven \n", "measures that facilitate implementation of practices that avoid, \n", "reduce, or reverse land degradation include tenure reform, tax Figure TS.8 | Interaction of human and climate drivers can exacerbate desertification and land degradation. Figure shows key desertification and \n", "land degradation issues, how they impact climate change, and the key drivers, with potential solutions.Climate change exacerbates the rate and magnitude \n", "of several ongoing land degradation and desertification processes. Human drivers of land degradation and desertification include expanding agriculture, agricultural \n", "practices and forest management. In turn, land degradation and desertification are also drivers of climate change through GHG emissions, reduced rates of carbon uptake, \n", "and reduced capacity of ecosystems to act as carbon sinks into the future. Impacts on climate change are either warming (in red) or cooling (in blue). Issue/ \n", "syndromeImpact on \n", "climate changeHuman \n", "driverClimate \n", "driverLand management \n", "optionsReferences\n", "Erosion of \n", "agricultural soilsEmission: CO2, N2OIncrease soil organic \n", "matter, no-till, perennial \n", "crops, erosion control, \n", "agroforestry, dietary change3.1.4, 3.4.1, \n", "3.5.2, 3.7.1, \n", "4.8.1, 4.8.5, \n", "4.9.2, 4.9.5\n", "Deforestation Emission of CO2Forest protection, sustain-\n", "able forest management \n", "and dietary change4.1.5, 4.5, 4.8.3, \n", "4.8.4, 4.9.3\n", "Forest degradationEmission of CO2\n", "Reduced carbon sinkForest protection, \n", "sustainable forest \n", "management4.1.5, 4.5, 4.8.3, \n", "4.8.4, 4.9.3\n", "OvergrazingEmission: CO2, CH4\n", "Increasing albedoControlled grazing, \n", "rangeland management3.1.4.2, 3.4.1, \n", "3.6.1, 3.7.1, \n", "4.8.1.4\n", "Firewood and \n", "charcoal productionEmission: CO2, CH4\n", "Increasing albedoClean cooking (health \n", "co-benefits, particularly \n", "for women and children)3.6.3, 4.5.4, \n", "4.8.3, 4.8.4\n", "Increasing fire \n", "frequency and \n", "intensityEmission: CO2, CH4, \n", "N2O\n", "Emission: aerosols,\n", "increasing albedoFuel management, \n", "fire management3.1.4, 3.6.1, \n", "4.1.5, 4.8.3, \n", "Cross-Chapter \n", "Box 3 in Chp 2\n", "Degradation of \n", "tropical peat soilsEmission: CO2, CH4Peatland restoration, \n", "erosion control, regulating \n", "the use of peat soils4.9.4\n", "Thawing of \n", "permafrostEmission: CO2, CH4Relocation of settlement \n", "and infrastructure4.8.5.1\n", "Coastal erosion Emission: CO2, CH4Wetland and coastal \n", "restoration, mangrove \n", "conservation, long-term \n", "land-use planning4 .9.6, 4.9. 7, \n", "4.9.8\n", "Sand and dust \n", "storms, wind \n", "erosionEmission: aerosolsVegetation management, \n", "afforestation, windbreaks3.3.1, 3.4.1, \n", "3.6.1, 3.7.1, 3.7.2\n", "Bush encroachmentCapturing: CO2,\n", "Decreasing albedoGrazing land management, \n", "fire management3.6.1.3, 3.7.3.2Human driver Climate driver\n", "Grazing \n", "pressureWarming \n", "trend\n", "Agriculture \n", "practiceExtreme \n", "temperature\n", "Expansion of \n", "agricultureDrying \n", "trend\n", "Forest \n", "clearingExtreme \n", "rainfall\n", "Wood \n", "fuelShifting \n", "rains\n", "Intensifying \n", "cyclones\n", "Sea level \n", "rise\n", "56\n", "Technical Summary\n", "TSincentives, payments for ecosystem services, participatory integrated \n", "land-use planning, farmer networks and rural advisory services. \n", "Delayed action increases the costs of addressing land degradation, \n", "and can lead to irreversible biophysical and human outcomes \n", "(high confidence). Early actions can generate both site-specific and \n", "immediate benefits to communities affected by land degradation, \n", "and contribute to long-term global benefits through climate change \n", "mitigation (high confidence). (Figure TS.7) {4.1.5, 4.1.6, 4.7.1, 4.8, \n", "Table 4.2}\n", "Even with adequate implementation of measures to avoid, \n", "reduce and reverse land degradation, there will be residual \n", "degradation in some situations (high confidence). Limits to \n", "adaptation are dynamic, site specific and determined through the \n", "interaction of biophysical changes with social and institutional \n", "conditions. Exceeding the limits of adaptation will trigger escalating \n", "losses or result in undesirable changes, such as forced migration, \n", "conflicts, or poverty. Examples of potential limits to adaptation due \n", "to climate-change-induced land degradation are coastal erosion \n", "(where land disappears, collapsing infrastructure and livelihoods due \n", "to thawing of permafrost), and extreme forms of soil erosion. {4.7, \n", "4.8.5, 4.8.6, 4.9.6, 4.9.7, 4.9.8} \n", "Land degradation is a serious and widespread problem, yet \n", "key uncertainties remain concerning its extent, severity, and \n", "linkages to climate change (very high confidence). Despite \n", "the difficulties of objectively measuring the extent and severity of \n", "land degradation, given its complex and value-based characteristics, \n", "land degradation represents – along with climate change – one of \n", "the biggest and most urgent challenges for humanity (very high \n", "confidence). The current global extent, severity and rates of land \n", "degradation are not well quantified. There is no single method by \n", "which land degradation can be measured objectively and consistently \n", "over large areas because it is such a complex and value-laden concept \n", "(very high confidence). However, many existing scientific and locally \n", "based approaches, including the use of ILK, can assess different \n", "aspects of land degradation or provide proxies. Remote sensing, \n", "corroborated by other data, can generate geographically explicit and \n", "globally consistent data that can be used as proxies over relevant \n", "time scales (several decades). Few studies have specifically addressed \n", "the impacts of proposed land-based negative emission technologies \n", "on land degradation. Much research has tried to understand how \n", "livelihoods and ecosystems are affected by a particular stressor – for \n", "example, drought, heat stress, or waterlogging. Important knowledge \n", "gaps remain in understanding how plants, habitats and ecosystems \n", "are affected by the cumulative and interacting impacts of several \n", "stressors, including potential new stressors resulting from large-scale \n", "implementation of negative emission technologies. {4.10}TS.5 Food security \n", "The current food system (production, transport, processing, \n", "packaging, storage, retail, consumption, loss and waste) feeds \n", "the great majority of world population and supports the \n", "livelihoods of over 1 billion people. Since 1961, food supply per \n", "capita has increased more than 30%, accompanied by greater use \n", "of nitrogen fertilisers (increase of about 800%) and water resources \n", "for irrigation (increase of more than 100%). However, an estimated \n", "821 million people are currently undernourished, 151 million children \n", "under five are stunted, 613 million women and girls aged 15 to 49 \n", "suffer from iron deficiency, and 2 billion adults are overweight or \n", "obese. The food system is under pressure from non-climate stressors \n", "(e.g., population and income growth, demand for animal-sourced \n", "products), and from climate change. These climate and non-climate \n", "stresses are impacting the four pillars of food security (availability, \n", "access, utilisation, and stability). (Figure TS.9) {5.1.1, 5.1.2}\n", "Observed climate change is already affecting food security \n", "through increasing temperatures, changing precipitation \n", "patterns, and greater frequency of some extreme events (high \n", "confidence). Studies that separate out climate change from other \n", "factors affecting crop yields have shown that yields of some crops \n", "(e.g., maize and wheat) in many lower-latitude regions have been \n", "affected negatively by observed climate changes, while in many \n", "higher-latitude regions, yields of some crops (e.g., maize, wheat, \n", "and sugar beets) have been affected positively over recent decades. \n", "Warming compounded by drying has caused large negative effects \n", "on yields in parts of the Mediterranean. Based on ILK, climate \n", "change is affecting food security in drylands, particularly those in \n", "Africa, and high mountain regions of Asia and South America. (Figure \n", "TS.10) {5.2.2}\n", "Food security will be increasingly affected by projected future \n", "climate change (high confidence). Across SSPs 1, 2, and 3, global \n", "crop and economic models projected a 1–29% cereal price increase \n", "in 2050 due to climate change (RCP 6.0), which would impact \n", "consumers globally through higher food prices; regional effects will \n", "vary (high confidence). Low-income consumers are particularly at \n", "risk, with models projecting increases of 1–183 million additional \n", "people at risk of hunger across the SSPs compared to a no climate \n", "change scenario (high confidence). While increased CO2 is projected \n", "to be beneficial for crop productivity at lower temperature increases, \n", "it is projected to lower nutritional quality (high confidence) (e.g., \n", "wheat grown at 546–586 ppm CO2 has 5.9–12.7% less protein, \n", "3.7–6.5% less zinc, and 5.2–7.5% less iron). Distributions of pests \n", "and diseases will change, affecting production negatively in many \n", "regions (high confidence). Given increasing extreme events and \n", "interconnectedness, risks of food system disruptions are growing \n", "(high confidence). {5.2.3, 5.2.4} \n", "Vulnerability of pastoral systems to climate change is very high \n", "(high confidence). Pastoralism is practiced in more than 75% of \n", "countries by between 200 and 500 million people, including nomadic \n", "communities, transhumant herders, and agropastoralists. Impacts \n", "in pastoral systems in Africa include lower pasture and animal \n", "productivity, damaged reproductive function, and biodiversity loss. \n", "Pastoral system vulnerability is exacerbated by non-climate factors \n", "57Technical Summary\n", "TS\n", "Figure TS.9 | Global trends in (a) yields of maize, rice, and wheat (FAOSTAT 2018) – the top three crops grown in the world; (b) production of crop and animal calories \n", "and use of crop calories as livestock feed (FAOSTAT 2018); (c) production from marine and aquaculture fi sheries (FishStat 2019); (d)land used for agriculture (FAOSTAT \n", "2018); (e)food trade in calories (FAOSTAT 2018); (f) food supply and required food (i.e., based on human energy requirements for medium physical activities) from \n", "1961–2012 (FAOSTAT 2018; Hiç et al. 2016); (g)prevalence of overweight, obesity and underweight from 1975–2015 (Abarca-Gómez et al. 2017); and (h) GHG emissions \n", "for the agriculture sector, excluding land-use change (FAOSTAT 2018). For fi gures (b) and (e), data provided in mass units were converted into calories using nutritive factors \n", "(FAO 2001b). Data on emissions due to burning of savanna and cultivation of organic soils is provided only after 1990 (FAOSTAT 2018).1960 1970 1980 1990 2000 2010012345\n", "Year(a)Yield (t/ha)\n", "Wheat yieldMaize yield\n", "Rice yield\n", "1960 1970 1980 1990 2000 201051015Calories ( 1015kcal/yr)(b)\n", "YearFeed use\n", "Animal productionCrop production\n", "1950 1960 1970 1980 1990 2000 20100510Fisheries ( 107tonnes)\n", "Year(c)\n", "AquacultureCaptured fisheries\n", "12345\n", "1960 1970 1980 1990 2000 2010\n", "YearLand use (in billion ha)(d)\n", "Permanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pasturesPermanent meadows and pastures\n", "Arable landArable landArable landArable landArable landArable landArable landArable landArable landArable landArable land\n", "Permanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent cropsPermanent crops\n", "1960 1970 1980 1990 2000 201000.511.522.533.5 Food Trade ( 1015kcal/yr)\n", "Year(e)\n", "Total\n", "Crop products\n", "Animal products\n", "050010001500200025003000\n", "1960 1970 1980 1990 2000 2010\n", "YearFood supply (kcal/cap/day)(f)\n", "CerealsCerealsCerealsCerealsCerealsCerealsCerealsCereals\n", "Animal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal ProductsAnimal Products\n", "Starchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy RootsStarchy Roots\n", "PulsesPulsesPulsesPulsesPulsesPulsesPulsesSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & productsSugar & products\n", "Oilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & productsOilcrops & products\n", "Fruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetablesFruits & vegetables\n", "OthersOthersOthersOthersOthersOthersOthersRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired foodRequired food\n", "051015202530\n", "1975 1985 1995 2005 2015Prevalence (%)\n", "Year(g)\n", "Overweight\n", "ObesityUnderweightMale\n", "Female\n", "1960 1970 1980 1990 2000 2010\n", "Year(h)\n", "012345Emissions (Gt C O2eq/yr)\n", "Enteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentationEnteric fermentation\n", "Manure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pastureManure left on pasture\n", "Manure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soilsManure applied to soils\n", "Manure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure managementManure management\n", "Synthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersSynthetic fertilizersPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivationPaddy rice cultivation\n", "Crop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residuesCrop residues\n", "Burning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residuesBurning − crop residues\n", "Burning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savannaBurning − savanna\n", "Cultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soilsCultivation of organic soils\n", "58\n", "Technical Summary\n", "TS(land tenure, sedentarisation, changes in traditional institutions, \n", "invasive species, lack of markets, and conflicts). {5.2.2}\n", "Fruit and vegetable production, a key component of healthy \n", "diets, is also vulnerable to climate change (medium evidence, \n", "high agreement). Declines in yields and crop suitability are projected \n", "under higher temperatures, especially in tropical and semi-tropical \n", "regions. Heat stress reduces fruit set and speeds up development of \n", "annual vegetables, resulting in yield losses, impaired product quality, \n", "and increasing food loss and waste. Longer growing seasons enable \n", "a greater number of plantings to be cultivated and can contribute \n", "to greater annual yields. However, some fruits and vegetables need \n", "a  period of cold accumulation to produce a viable harvest, and \n", "warmer winters may constitute a risk. {5.2.2}\n", "Food security and climate change have strong gender and \n", "equity dimensions (high confidence). Worldwide, women play \n", "a key role in food security, although regional differences exist. \n", "Climate change impacts vary among diverse social groups depending \n", "on age, ethnicity, gender, wealth, and class. Climate extremes \n", "have immediate and long-term impacts on livelihoods of poor \n", "and vulnerable communities, contributing to greater risks of food \n", "insecurity that can be a stress multiplier for internal and external \n", "migration (medium confidence). Empowering women and rights-\n", "based approaches to decision-making can create synergies among \n", "household food security, adaptation, and mitigation. {5.2.6, 5.6.4} \n", "Many practices can be optimised and scaled up to advance \n", "adaptation throughout the food system (high confidence). \n", "Supply-side options include increased soil organic matter and \n", "erosion control, improved cropland, livestock, grazing land \n", "management, and genetic improvements for tolerance to heat and \n", "drought. Diversification in the food system (e.g., implementation \n", "of integrated production systems, broad-based genetic resources, \n", "and heterogeneous diets) is a key strategy to reduce risks (medium \n", "confidence). Demand-side adaptation, such as adoption of healthy \n", "and sustainable diets, in conjunction with reduction in food loss and \n", "waste, can contribute to adaptation through reduction in additional \n", "land area needed for food production and associated food system \n", "vulnerabilities. ILK can contribute to enhancing food system resilience \n", "(high confidence). {5.3, 5.6.3 Cross-Chapter Box 6 in Chapter 5}.\n", "About 21–37% of total greenhouse gas (GHG) emissions are \n", "attributable to the food system. These are from agriculture \n", "and land use, storage, transport, packaging, processing, retail, \n", "and consumption (medium confidence). This estimate includes \n", "emissions of 9–14% from crop and livestock activities within the \n", "farm gate and 5–14% from land use and land-use change including \n", "deforestation and peatland degradation (high confidence); 5–10% \n", "is from supply chain activities (medium confidence). This estimate \n", "includes GHG emissions from food loss and waste. Within the food \n", "system, during the period 2007–2016, the major sources of emissions \n", "from the supply side were agricultural production, with crop and \n", "livestock activities within the farm gate generating respectively \n", "142 ± 42 TgCH4 yr–1 (high confidence) and 8.0 ± 2.5 TgN2O yr–1 \n", "(high confidence), and CO2 emissions linked to relevant land-use \n", "change dynamics such as deforestation and peatland degradation, \n", "generating 4.9 ± 2.5 GtCO2 yr–1. Using 100-year GWP values (no climate feedback) from the IPCC AR5, this implies that total GHG \n", "emissions from agriculture were 6.2 ± 1.4 GtCO2-eq yr–1, increasing \n", "to 11.1 ± 2.9 GtCO2-eq yr–1 including relevant land use. Without \n", "intervention, these are likely to increase by about 30–40% by 2050, \n", "due to increasing demand based on population and income growth \n", "and dietary change (high confidence). {5.4} \n", "Supply-side practices can contribute to climate change \n", "mitigation by reducing crop and livestock emissions, \n", "sequestering carbon in soils and biomass, and by decreasing \n", "emissions intensity within sustainable production systems \n", "(high confidence). Total technical mitigation potential from \n", "crop and livestock activities and agroforestry is estimated as \n", "2.3–9.6 GtCO2-eq yr–1 by 2050 (medium confidence). Options with \n", "large potential for GHG mitigation in cropping systems include soil \n", "carbon sequestration (at decreasing rates over time), reductions \n", "in N2O emissions from fertilisers, reductions in CH4 emissions from \n", "paddy rice, and bridging of yield gaps. Options with large potential \n", "for mitigation in livestock systems include better grazing land \n", "management, with increased net primary production and soil carbon \n", "stocks, improved manure management, and higher-quality feed. \n", "Reductions in GHG emissions intensity (emissions per unit product) \n", "from livestock can support reductions in absolute emissions, provided \n", "appropriate governance to limit total production is implemented at \n", "the same time (medium confidence). {5.5.1} \n", "Consumption of healthy and sustainable diets presents major \n", "opportunities for reducing GHG emissions from food systems \n", "and improving health outcomes (high confidence). Examples of \n", "healthy and sustainable diets are high in coarse grains, pulses, fruits \n", "and vegetables, and nuts and seeds; low in energy-intensive animal-\n", "sourced and discretionary foods (such as sugary beverages); and \n", "with a carbohydrate threshold. Total technical mitigation potential \n", "of dietary changes is estimated as 0.7–8.0 GtCO2-eq yr–1 by 2050 \n", "(medium confidence). This estimate includes reductions in emissions \n", "from livestock and soil carbon sequestration on spared land, but co-\n", "benefits with health are not taken into account. Mitigation potential \n", "of dietary change may be higher, but achievement of this potential at \n", "broad scales depends on consumer choices and dietary preferences \n", "that are guided by social, cultural, environmental, and traditional \n", "factors, as well as income growth. Meat analogues such as imitation \n", "meat (from plant products), cultured meat, and insects may help in \n", "the transition to more healthy and sustainable diets, although their \n", "carbon footprints and acceptability are uncertain. {5.5.2, 5.6.5}\n", "Reduction of food loss and waste could lower GHG emissions \n", "and improve food security (medium confidence). Combined food \n", "loss and waste amount to 25–30% of total food produced (medium \n", "confidence). During 2010–2016, global food loss and waste equalled \n", "8–10% of total anthropogenic GHG emissions (medium confidence); \n", "and cost about 1 trillion USD2012 per year (low confidence). \n", "Technical options for reduction of food loss and waste include \n", "improved harvesting techniques, on-farm storage, infrastructure, and \n", "packaging. Causes of food loss (e.g., lack of refrigeration) and waste \n", "(e.g., behaviour) differ substantially in developed and developing \n", "countries, as well as across regions (robust evidence, medium \n", "agreement). {5.5.2}\n", "59Technical Summary\n", "TS\n", "Agriculture and the food system are key to global climate \n", "change responses. Combining supply-side actions such as \n", "effi cient production, transport, and processing with demand-\n", "side interventions such as modifi cation of food choices, and \n", "reduction of food loss and waste, reduces GHG emissions \n", "and enhances food system resilience (high confi dence).\n", "Such combined measures can enable the implementation of large-\n", "scale land-based adaptation and mitigation strategies without \n", "threatening food security from increased competition for land for \n", "food production and higher food prices. Without combined food \n", "system measures in farm management, supply chains, and demand, \n", "adverse effects would include increased numbers of malnourished \n", "people and impacts on smallholder farmers (medium evidence, high \n", "agreement). Just transitions are needed to address these effects. \n", "(Figure TS.11) {5.5, 5.6, 5.7}For adaptation and mitigation throughout the food system, \n", "enabling conditions need to be created through policies, \n", "markets, institutions, and governance (high confi dence).\n", "For adaptation, resilience to increasing extreme events can be \n", "accomplished through risk sharing and transfer mechanisms such \n", "as insurance markets and index-based weather insurance (high \n", "confi dence). Public health policies to improve nutrition – such as \n", "school procurement, health insurance incentives, and awareness-\n", "raising campaigns – can potentially change demand, reduce \n", "healthcare costs, and contribute to lower GHG emissions (limited \n", "evidence, high agreement). Without inclusion of comprehensive food \n", "system responses in broader climate change policies, the mitigation \n", "and adaptation potentials assessed in Chapter 5 will not be realised \n", "and food security will be jeopardised (high confi dence). {5.7.5}Figure TS.10 | AgMIP median yield changes (%) for RCP8.5 (2070–2099 in comparison to 1980–2010 baseline) with CO2 effects and explicit nitrogen stress over \n", "fi ve GCMs χ four Global Gridded Crop Models (GGCMs) for rainfed maize, wheat, rice, and soy (20 ensemble members from EPIC, GEPIC, pDSSAT, and PEGASUS; except \n", "for rice which has 15). Grey areas indicate historical areas with little to no yield capacity. All models use a 0.5° grid, but there are differences in grid cells simulated to \n", "represent agricultural land. While some models simulated all land areas, others simulated only potential suitable cropland area according to evolving climatic conditions. \n", "Others utilised historical harvested areas in 2000 according to various data sources (Rosenzweig et al. 2014).\n", "GGCMs with explicit N stress\n", "Maize Wheat\n", "Rice Soy\n", "%\n", "0<-50 >50\n", "60\n", "Technical Summary\n", "TSFigure TS.11 | Response options related to food system and their potential impacts on mitigation and adaptation. Many response options offer significant \n", "potential for both mitigation and adaptation. Food system response options\n", "Response options\n", "Increased soil organic matter content\n", "Change in crop variety\n", "Improved water management\n", "Adjustment of planting dates\n", "Precision fertiliser management\n", "Integrated pest management\n", "Counter season crop production\n", "Biochar application\n", "Agroforestry\n", "Changing monoculture to crop diversification\n", "Changes in cropping area, land rehabilitation (enclosures, afforestation) perennial farming\n", "Crop–livestock systemsImproved crop management\n", "Silvopastural system\n", "New livestock breed\n", "Livestock fattening\n", "Shifting to small ruminants or drought-resistant livestock or fish farming\n", "Feed and fodder banks\n", "Methane inhibitors\n", "Thermal stress control\n", "Seasonal feed supplementation\n", "Improved animal health and parasites controlImproved livestock\n", "managment\n", "Early warning systems\n", "Planning and prediction at seasonal to intra-seasonal climate risk\n", "Crop and livestock insurance\n", "Food storage infrastructures\n", "Shortening supply chains\n", "Improved food transport and distribution\n", "Improved efficiency and sustainability of food processing, retail and agrifood industries\n", "Improved energy efficiencies of agriculture\n", "Reduce food loss\n", "Urban and peri-urban agriculture\n", "Bioeconomy (e.g. energy from waste)Improved supply chain\n", "Dietary changes\n", "Reduce food waste\n", "Packaging reductions\n", "New ways of selling (e.g. direct sales)\n", "Transparency of food chains and external costsDemand\n", " managementClimate\n", "servicesMitigation Adaptation\n", "Tillage and crop establishment\n", "Residue managementMitigation and adaptation potential\n", "Very high High \n", "Limited None\n", "61\n", "Technical SummaryTSTS.6 Interlinkages between desertification, \n", "land degradation, food security and \n", "GHG fluxes: Synergies, trade-offs and \n", "integrated response options\n", "The land challenges, in the context of this report, are \n", "climate change mitigation, adaptation, desertification, land \n", "degradation, and food security. The chapter also discusses \n", "implications for Nature’s Contributions to People (NCP), including \n", "biodiversity and water, and sustainable development, by assessing \n", "intersections with the Sustainable Development Goals (SDGs). The \n", "chapter assesses response options that could be used to address these \n", "challenges. These response options were derived from the previous \n", "chapters and fall into three broad categories: land management, \n", "value chain, and risk management.\n", "The land challenges faced today vary across regions; climate \n", "change will increase challenges in the future, while socio-\n", "economic development could either increase or decrease \n", "challenges (high confidence). Increases in biophysical impacts from \n", "climate change can worsen desertification, land degradation, and \n", "food insecurity (high confidence). Additional pressures from socio-\n", "economic development could further exacerbate these challenges; \n", "however, the effects are scenario dependent. Scenarios with increases \n", "in income and reduced pressures on land can lead to reductions in \n", "food insecurity; however, all assessed scenarios result in increases in \n", "water demand and water scarcity (medium confidence). {6.1} \n", "The applicability and efficacy of response options are \n", "region and context specific; while many value chain and risk \n", "management options are potentially broadly applicable, many \n", "land management options are applicable on less than 50% of \n", "the ice-free land surface (high confidence). Response options \n", "are limited by land type, bioclimatic region, or local food system \n", "context (high confidence). Some response options produce adverse \n", "side effects only in certain regions or contexts; for example, response \n", "options that use freshwater may have no adverse side effects in \n", "regions where water is plentiful, but large adverse side effects in \n", "regions where water is scarce (high confidence). Response options \n", "with biophysical climate effects (e.g., afforestation, reforestation) \n", "may have different effects on local climate, depending on where they \n", "are implemented (medium confidence). Regions with more challenges \n", "have fewer response options available for implementation (medium \n", "confidence). {6.1, 6.2, 6.3, 6.4}\n", "Nine options deliver medium-to-large benefits for all five land \n", "challenges (high confidence). The options with medium-to-large \n", "benefits for all challenges are increased food productivity, improved \n", "cropland management, improved grazing land management, \n", "improved livestock management, agroforestry, forest management, \n", "increased soil organic carbon content, fire management and \n", "reduced post-harvest losses. A further two options, dietary change \n", "and reduced food waste, have no global estimates for adaptation \n", "but have medium-to-large benefits for all other challenges (high \n", "confidence). {6.3, 6.4}Five options have large mitigation potential (>3 GtCO2e yr–1) \n", "without adverse impacts on the other challenges (high \n", "confidence). These are: increased food productivity; reduced \n", "deforestation and forest degradation; increased soil organic carbon \n", "content; fire management; and reduced post-harvest losses. Two \n", "further options with large mitigation potential, dietary change \n", "and reduced food waste, have no global estimates for adaptation \n", "but show no negative impacts across the other challenges. Five \n", "options: improved cropland management; improved grazing land \n", "managements; agroforestry; integrated water management; and \n", "forest management, have moderate mitigation potential, with no \n", "adverse impacts on the other challenges (high confidence). {6.3.6}\n", "Sixteen response options have large adaptation potential (more \n", "than 25 million people benefit), without adverse side effects \n", "on other land challenges (high confidence). These are increased \n", "food productivity, improved cropland management, agroforestry, \n", "agricultural diversification, forest management, increased soil \n", "organic carbon content, reduced landslides and natural hazards, \n", "restoration and reduced conversion of coastal wetlands, reduced \n", "post-harvest losses, sustainable sourcing, management of supply \n", "chains, improved food processing and retailing, improved energy \n", "use in food systems, livelihood diversification, use of local seeds, and \n", "disaster risk management (high confidence). Some options (such as \n", "enhanced urban food systems or management of urban sprawl) may \n", "not provide large global benefits but may have significant positive \n", "local effects without adverse effects (high confidence). (Figure TS.13) \n", "{6.3, 6.4}\n", "Seventeen of 40 options deliver co-benefits or no adverse \n", "side effects for the full range of NCPs and SDGs; only three \n", "options (afforestation, BECCS), and some types of risk sharing \n", "instruments, such as insurance) have potentially adverse side \n", "effects for five or more NCPs or SDGs (medium confidence). \n", "The 17 options with co-benefits and no adverse side effects include \n", "most agriculture- and soil-based land management options, many \n", "ecosystem-based land management options, forest management, \n", "reduced post-harvest losses, sustainable sourcing, improved \n", "energy use in food systems, and livelihood diversification (medium \n", "confidence). Some of the synergies between response options and \n", "SDGs include positive poverty eradication impacts from activities like \n", "improved water management or improved management of supply \n", "chains. Examples of synergies between response options and NCPs \n", "include positive impacts on habitat maintenance from activities \n", "like invasive species management and agricultural diversification. \n", "However, many of these synergies are not automatic, and are \n", "dependent on well-implemented activities requiring institutional and \n", "enabling conditions for success. {6.4}\n", "Most response options can be applied without competing for \n", "available land; however, seven options result in competition \n", "for land (medium confidence). A large number of response options \n", "do not require dedicated land, including several land management \n", "options, all value chain options, and all risk management options. \n", "Four options could greatly increase competition for land if applied at \n", "scale: afforestation, reforestation, and land used to provide feedstock \n", "for BECCS or biochar, with three further options: reduced grassland \n", "62\n", "Technical Summary\n", "TSconversion to croplands, restoration and reduced conversion of \n", "peatlands and restoration, and reduced conversion of coastal \n", "wetlands having smaller or variable impacts on competition for land. \n", "Other options such as reduced deforestation and forest degradation, \n", "restrict land conversion for other options and uses. Expansion of the \n", "current area of managed land into natural ecosystems could have \n", "negative consequences for other land challenges, lead to the loss of \n", "biodiversity, and adversely affect a range of NCPs (high confidence). \n", "{6.3.6, 6.4}\n", "Some options, such as bioenergy and BECCS, are scale \n", "dependent. The climate change mitigation potential for \n", "bioenergy and BECCS is large (up to 11 GtCO2 yr–1); however, \n", "the effects of bioenergy production on land degradation, \n", "food insecurity, water scarcity, GHG emissions, and other \n", "environmental goals are scale- and context-specific (high \n", "confidence). These effects depend on the scale of deployment, \n", "initial land use, land type, bioenergy feedstock, initial carbon \n", "stocks, climatic region and management regime (high confidence). \n", "Large areas of monoculture bioenergy crops that displace other \n", "land uses can result in land competition, with adverse effects for \n", "food production, food consumption, and thus food security, as well \n", "as adverse effects for land degradation, biodiversity, and water \n", "scarcity (medium confidence). However, integration of bioenergy into \n", "sustainably managed agricultural landscapes can ameliorate these \n", "challenges (medium confidence). {6.2, 6.3, 6.4, Cross-Chapter Box 7 \n", "in Chapter 6}\n", "Response options are interlinked; some options (e.g., land \n", "sparing and sustainable land management options) can \n", "enhance the co-benefits or increase the potential for other \n", "options (medium confidence). Some response options can be \n", "more effective when applied together (medium confidence); for \n", "example, dietary change and waste reduction expand the potential to \n", "apply other options by freeing as much as 5.8 Mkm2 (0.8–2.4 Mkm2 \n", "for dietary change; about 2 Mkm2 for reduced post-harvest losses, \n", "and 1.4 Mkm2 for reduced food waste) of land (low confidence). \n", "Integrated water management and increased soil organic carbon can \n", "increase food productivity in some circumstances. {6.4}\n", "Other response options (e.g., options that require land) may \n", "conflict; as a result, the potentials for response options are \n", "not all additive, and a total potential from the land is currently \n", "unknown (high confidence). Combining some sets of options (e.g., \n", "those that compete for land) may mean that maximum potentials \n", "cannot be realised, for example, reforestation, afforestation, and \n", "bioenergy and BECCS, all compete for the same finite land resource \n", "so the combined potential is much lower than the sum of potentials \n", "of each individual option, calculated in the absence of alternative \n", "uses of the land (high confidence). Given the interlinkages among \n", "response options and that mitigation potentials for individual options \n", "assume that they are applied to all suitable land, the total mitigation \n", "potential is much lower than the sum of the mitigation potential of \n", "the individual response options (high confidence). (Figure TS.12) {6.4}\n", "The feasibility of response options, including those with \n", "multiple co-benefits, is limited due to economic, technological, institutional, socio-cultural, environmental and geophysical \n", "barriers (high confidence). A number of response options (e.g., most \n", "agriculture-based land management options, forest management, \n", "reforestation and restoration) have already been implemented \n", "widely to date (high confidence). There is robust evidence that many \n", "other response options can deliver co-benefits across the range of \n", "land challenges, yet these are not being implemented. This limited \n", "application is evidence that multiple barriers to implementation of \n", "response options exist (high confidence). {6.3, 6.4}\n", "Coordinated action is required across a range of actors, \n", "including business, producers, consumers, land managers, \n", "indigenous peoples and local communities and policymakers \n", "to create enabling conditions for adoption of response options \n", "(high confidence). The response options assessed face a variety of \n", "barriers to implementation (economic, technological, institutional, \n", "socio-cultural, environmental and geophysical) that require action \n", "across multiple actors to overcome (high confidence). There are a \n", "variety of response options available at different scales that could \n", "form portfolios of measures applied by different stakeholders – from \n", "farm to international scales. For example, agricultural diversification \n", "and use of local seeds by smallholders can be particularly useful \n", "poverty eradication and biodiversity conservation measures, but are \n", "only successful when higher scales, such as national and international \n", "markets and supply chains, also value these goods in trade regimes, \n", "and consumers see the benefits of purchasing these goods. However, \n", "the land and food sectors face particular challenges of institutional \n", "fragmentation, and often suffer from a lack of engagement between \n", "stakeholders at different scales (medium confidence). {6.3, 6.4}\n", "Delayed action will result in an increased need for response \n", "to land challenges and a decreased potential for land-based \n", "response options due to climate change and other pressures \n", "(high confidence). For example, failure to mitigate climate change \n", "will increase requirements for adaptation and may reduce the efficacy \n", "of future land-based mitigation options (high confidence). The \n", "potential for some land management options decreases as climate \n", "change increases; for example, climate alters the sink capacity for \n", "soil and vegetation carbon sequestration, reducing the potential \n", "for increased soil organic carbon (high confidence). Other options \n", "(e.g., reduced deforestation and forest degradation) prevent further \n", "detrimental effects to the land surface; delaying these options could \n", "lead to increased deforestation, conversion, or degradation, serving \n", "as increased sources of GHGs and having concomitant negative \n", "impacts on NCPs (medium confidence). Carbon dioxide removal \n", "(CDR) options – such as reforestation, afforestation, bioenergy and \n", "BECCS – are used to compensate for unavoidable emissions in other \n", "sectors; delayed action will result in larger and more rapid deployment \n", "later (high confidence). Some response options will not be possible \n", "if action is delayed too long; for example, peatland restoration might \n", "not be possible after certain thresholds of degradation have been \n", "exceeded, meaning that peatlands could not be restored in certain \n", "locations (medium confidence) {6.2, 6.3, 6.4}.\n", "Early action, however, has challenges including technological \n", "readiness, upscaling, and institutional barriers (high \n", "confidence). Some of the response options have technological \n", "63\n", "Technical SummaryTSbarriers that may limit their wide-scale application in the near term \n", "(high confidence). Some response options, for example, BECCS, \n", "have only been implemented at small-scale demonstration facilities; \n", "challenges exist with upscaling these options to the levels discussed in \n", "Chapter 6 (medium confidence). Economic and institutional barriers, \n", "including governance, financial incentives and financial resources, \n", "limit the near-term adoption of many response options, and ‘policy \n", "lags’, by which implementation is delayed by the slowness of the \n", "policy implementation cycle, are significant across many options \n", "(medium confidence). Even some actions that initially seemed like \n", "‘easy wins’ have been challenging to implement, with stalled policies \n", "for reducing emissions from deforestation and forest degradation \n", "and fostering conservation (REDD+) providing clear examples of how \n", "response options need sufficient funding, institutional support, local \n", "buy-in, and clear metrics for success, among other necessary enabling \n", "conditions. {6.2, 6.4}\n", "Some response options reduce the consequences of land \n", "challenges, but do not address underlying drivers (high \n", "confidence). For example, management of urban sprawl can help \n", "reduce the environmental impact of urban systems; however, such management does not address the socio-economic and demographic \n", "changes driving the expansion of urban areas. By failing to address \n", "the underlying drivers, there is a potential for the challenge to \n", "re-emerge in the future (high confidence). {6.4}\n", "Many response options have been practised in many regions \n", "for many years; however, there is limited knowledge of the \n", "efficacy and broader implications of other response options \n", "(high confidence). For the response options with a large evidence \n", "base and ample experience, further implementation and upscaling \n", "would carry little risk of adverse side effects (high confidence). \n", "However, for other options, the risks are larger as the knowledge \n", "gaps are greater; for example, uncertainty in the economic and \n", "social aspects of many land response options hampers the ability to \n", "predict their effects (medium confidence). Furthermore, Integrated \n", "Assessment Models, like those used to develop the pathways in the \n", "IPCC Special Report on Global Warming of 1.5°C (SR15), omit many \n", "of these response options and do not assess implications for all land \n", "challenges (high confidence). {6.4}\n", "Croplands Semi-natural forests\n", "Dense settlements Rangelands Wild forests and sparse trees\n", "VillagesWetlands and organic soils\n", "Potential deployment (% global ice-free land area)0 10 20 30 40 50 60 70 80Restoration and reduced conversion of coastal wetlandRestoration and reduced conversion of peatlandBioenergy and BECCSReduced grassland conversion to croplandCropland managementReforestationForest management and restorationIncreased food productivityReduced deforestation and degradationLivestock managementImproved grazing managementAgroforestryIncreased soil organic carbonFire management\n", "Figure TS.12 | Potential deployment area of land management responses (see Table 6.1) across land-use types (or anthromes, see Section 6.3), when \n", "selecting responses having only co-benefits for local challenges and for climate change mitigation and no large adverse side effects on global food \n", "security. See Figure 6.2 for the criteria used to map challenges considered (desertification, land degradation, climate change adaptation, chronic undernourishment, \n", "biodiversity, groundwater stress and water quality). No response option was identified for barren lands.\n", "64Technical Summary\n", "TS\n", "Figure TS.13 | Potential global contribution of response options to mitigation, adaptation, combating desertifi cation and land degradation, \n", "and enhancing food security (Panel A). SPM approved draft IPCC SRCCL | Page 28 Subject to copy edit and layoutMillion km/two.numr Million people Million km/two.numr Million people Gt CO/two.dnom-eq yr–1Desertification Food Security Land Degradation Adaptation Mitigation\n", "Large\n", "Large\n", "Variable: Can be positive or negativeModerate\n", "ModerateSmall\n", "SmallNegligibleMore than 3\n", "More than -30.3 to 3\n", "-0.3 to -3Less than 0.3\n", "No effect\n", "Less than -0.3Positive for\n", "more than 25Positive for\n", "more than 100Positive for\n", "more than 3Positive for\n", "more than 3\n", "Negative for\n", "more than 25Negative for\n", "more than 100Negative for\n", "more than 3Negative for\n", "more than 31 to 25\n", "1 to 25Less than 1\n", "No effect\n", "Less than 11 to 100\n", "1 to 100Less than 1\n", "No effect\n", "Less than 10.5 to 3\n", "0.5 to 3Less than 0.5\n", "No effect\n", "Less than 0.50.5 to 3\n", "0.5 to 3Less than 0.5\n", "No effect\n", "Less than 0.5Confidence level Key for criteria used to define magnitude of impact of each integrated response option\n", "Indicates confidence in the \n", "estimate of magnitude category.\n", "High confidence H\n", "Medium confidenceM\n", "Low confidenceL\n", "Cost range\n", "See technical caption for cost \n", "ranges in US$ tCO/two.dnome/endash.sups/one.sups or US$ ha/endash.sups/one.sups. \n", "High cost\n", "Medium cost\n", "Low cost\n", "no data not applicablePositive Negative\n", "no data naResponse options based on land management\n", "Increased food productivity\n", "Agro-forestry\n", "Improved cropland management\n", "Improved livestock management\n", "Agricultural diversification\n", "Improved grazing land management\n", "Integrated water management\n", "Reduced grassland conversion to cropland\n", "Forest management\n", "Reduced deforestation and forest degradation\n", "Increased soil organic carbon content\n", "Reduced soil erosion\n", "Reduced soil salinization\n", "Reduced soil compaction\n", "Fire management\n", "Reduced landslides and natural hazards\n", "Reduced pollution including acidification\n", "Response options based on value chain management\n", "Response options based on risk managementRestoration & reduced conversion of coastal wetlands\n", "Restoration & reduced conversion of peatlands\n", "Reduced post-harvest losses\n", "Dietary change\n", "Reduced food waste (consumer or retailer)\n", "Sustainable sourcing\n", "Improved food processing and retailing\n", "Improved energy use in food systems\n", "Livelihood diversification\n", "Management of urban sprawl\n", "Risk sharing instrumentsAgriculture Forests Soils Demand Supply Other ecosystemsDesertification Food Security Cost Land Degradation Adaptation Mitigation\n", "L M L M H\n", "M M M M L\n", "M L L L L\n", "M L L L L\n", "L L L M L\n", "M L L L L\n", "L L L L L\n", "L L L L\n", "M L L L L\n", "H L L L L\n", "H L M M L\n", "L L M M L\n", "L L L L\n", "L L L\n", "M M M M L\n", "L L L L L\n", "M M L L L\n", "M L M M L\n", "M na M L\n", "H M L L H\n", "H L H H\n", "H L M M\n", "L L L\n", "L L L\n", "L L L\n", "L L L LRiskL L L\n", "L L M L\n", "Options shown are those for which data are available to assess global potential for three or more land challenges.\n", "The magnitudes are assessed independently for each option and are not additive.Panel A shows response options that can be implemented without or with limited competition for land, including some that have the \n", "potential to reduce the demand for land. Co-benefits and adverse side effects are shown quantitatively based on the high end of the \n", "range of potentials assessed. Magnitudes of contributions are categorised using thresholds for positive or negative impacts. Letters \n", "within the cells indicate confidence in the magnitude of the impact relative to the thresholds used (see legend). Confidence in the \n", "direction of change is generally higher.Potential global contribution of response options to mitigation, adaptation, \n", "combating desertification and land degradation, and enhancing food security\n", "65\n", "Technical SummaryTS\n", "Figure TS.13 | Potential global contribution of response options to mitigation, adaptation, combating desertification and land degradation, and \n", "enhancing food security (Panel B). SPM approved draft IPCC SRCCL | Page 29 Subject to copy edit and layoutPanel B shows response options that rely on additional land-use change and could have implications across three or more land \n", "challenges under different implementation contexts. For each option, the first row (high level implementation) shows a quantitative \n", "assessment (as in Panel A) of implications for global implementation at scales delivering CO/two.dnom removals of more than 3 GtCO/two.dnom yr–1 using \n", "the magnitude thresholds shown in Panel A. The red hatched cells indicate an increasing pressure but unquantified impact. For each \n", "option, the second row (best practice implementation) shows qualitative estimates of impact if implemented using best practices in \n", "appropriately managed landscape systems that allow for efficient and sustainable resource use and supported by appropriate \n", "governance mechanisms. In these qualitative assessments, green indicates a positive impact, grey indicates a neutral interaction. Potential global contribution of response options to mitigation, adaptation, \n", "combating desertification and land degradation, and enhancing food security\n", "Mitigation Adaptation Desertification Land degradation Food security Cost\n", "Mitigation Adaptation Desertification Land degradation Food securityBioenergy and BECCS\n", "High level: Impacts on adaptation, desertification, land degradation and food security are maximum potential impacts, assuming carbon dioxide removal by BECCS \n", "at a scale of 11.3 GtCO/two.dnom yr–1 in 2050, and noting that bioenergy without CCS can also achieve emissions reductions of up to several GtCO/two.dnom yr–1 when it is a low carbon\n", "energy source {2.6.1; 6.3.1}. Studies linking bioenergy to food security estimate an increase in the population at risk of hunger to up to 150 million people at this level\n", "of implementation {6.3.5}. The red hatched cells for desertification and land degradation indicate that while up to 15 million km2 of additional land is required in 2100\n", "in 2°C scenarios which will increase pressure for desertification and land degradation, the actual area affected by this additional pressure is not easily quantified\n", "{6.3.3; 6.3.4}. \n", "Best practice: The sign and magnitude of the effects of bioenergy and BECCS depends on the scale of deployment, the type of bioenergy feedstock, which other \n", "response options are included, and where bioenergy is grown (including prior land use and indirect land use change emissions). For example, limiting bioenergy \n", "production to marginal lands or abandoned cropland would have negligible effects on biodiversity, food security, and potentially co-benefits for land degradation; \n", "however, the benefits for mitigation could also be smaller. {Table 6.58}\n", "Mitigation Adaptation Desertification Land degradation Food security Cost\n", "Mitigation Adaptation Desertification Land degradation Food securityReforestation and forest restoration\n", "High level: Impacts on adaptation, desertification, land degradation and food security are maximum potential impacts assuming implementation of reforestation \n", "and forest restoration (partly overlapping with afforestation) at a scale of 10.1 GtCO/two.dnom yr–1 removal {6.3.1}. Large-scale afforestation could cause increases in food prices \n", "of 80% by 2050, and more general mitigation measures in the AFOLU sector can translate into a rise in undernourishment of 80–300 million people; the impact of \n", "reforestation is lower {6.3.5}.\n", "Best practice: There are co-benefits of reforestation and forest restoration in previously forested areas, assuming small scale deployment using native species and \n", "involving local stakeholders to provide a safety net for food security. Examples of sustainable implementation include, but are not limited to, reducing illegal logging \n", "and halting illegal forest loss in protected areas, reforesting and restoring forests in degraded and desertified lands {Box6.1C; Table 6.6}.\n", "Mitigation Adaptation Desertification Land degradation Food security Cost\n", "Mitigation Adaptation Desertification Land degradation Food securityAfforestation\n", "High level: Impacts on adaptation, desertification, land degradation and food security are maximum potential impacts assuming implementation of afforestation \n", "(partly overlapping with reforestation and forest restoration) at a scale of 8.9 GtCO/two.dnom yr–1 removal {6.3.1}. Large-scale afforestation could cause increases in food prices \n", "of 80% by 2050, and more general mitigation measures in the AFOLU sector can translate into a rise in undernourishment of 80–300 million people {6.3.5}.\n", "Best practice: Afforestation is used to prevent desertification and to tackle land degradation. Forested land also offers benefits in terms of food supply, especially \n", "when forest is established on degraded land, mangroves, and other land that cannot be used for agriculture. For example, food from forests represents a safety-net \n", "during times of food and income insecurity {6.3.5}.\n", "Mitigation Adaptation Desertification Land degradation Food security Cost\n", "Mitigation Adaptation Desertification Land degradation Food securityBiochar addition to soil\n", "High level: Impacts on adaptation, desertification, land degradation and food security are maximum potential impacts assuming implementation of biochar at a scale \n", "of 6.6 GtCO/two.dnom yr–1 removal {6.3.1}. Dedicated biomass crops required for feedstock production could occupy 0.4–2.6 Mkm/two.numr of land, equivalent to around 20% of the global \n", "cropland area, which could potentially have a large effect on food security for up to 100 million people {6.3.5}.\n", "Best practice: When applied to land, biochar could provide moderate benefits for food security by improving yields by 25% in the tropics, but with more limited \n", "impacts in temperate regions, or through improved water holding capacity and nutrient use efficiency. Abandoned cropland could be used to supply biomass for \n", "biochar, thus avoiding competition with food production; 5–9 Mkm/two.numr of land is estimated to be available for biomass production without compromising food security \n", "and biodiversity, considering marginal and degraded land and land released by pasture intensification {6.3.5}.H L L\n", "M M M M M\n", "M M M L M\n", "M X X L L\n", "66\n", "Technical Summary\n", "TSFigure TS.13 (continued): This Figure is based on an aggregation of information from studies with a wide variety of assumptions about how response options are \n", "implemented and the contexts in which they occur. Response options implemented differently at local to global scales could lead to different outcomes. Magnitude \n", "of potential: For panel A, magnitudes are for the technical potential of response options globally. For each land challenge, magnitudes are set relative to a marker \n", "level as follows. For mitigation, potentials are set relative to the approximate potentials for the response options with the largest individual impacts (~3 GtCO2-eq yr–1). \n", "The threshold for the ‘large’ magnitude category is set at this level. For adaptation, magnitudes are set relative to the 100 million lives estimated to be affected by \n", "climate change and a carbon-based economy between 2010 and 2030. The threshold for the ‘large’ magnitude category represents 25% of this total. For desertification \n", "and land degradation, magnitudes are set relative to the lower end of current estimates of degraded land, 10–60 million km2. The threshold for the ‘large’ magnitude \n", "category represents 30% of the lower estimate. For food security, magnitudes are set relative to the approximately 800 million people who are currently undernourished. \n", "The threshold for the ‘large’ magnitude category represents 12.5% of this total. For panel B, for the first row (high level implementation) for each response option, the \n", "magnitude and thresholds are as defined for panel A. In the second row (best practice implementation) for each response option, the qualitative assessments that are \n", "green denote potential positive impacts, and those shown in grey indicate neutral interactions. Increased food production is assumed to be achieved through sustainable \n", "intensification rather than through injudicious application of additional external inputs such as agrochemicals. Levels of confidence: Confidence in the magnitude \n", "category (high, medium or low) into which each option falls for mitigation, adaptation, combating desertification and land degradation, and enhancing food security. \n", "High confidence means that there is a high level of agreement and evidence in the literature to support the categorisation as high, medium or low magnitude. Low \n", "confidence denotes that the categorisation of magnitude is based on few studies. Medium confidence reflects medium evidence and agreement in the magnitude \n", "of response. Cost ranges: Cost estimates are based on aggregation of often regional studies and vary in the components of costs that are included. In panel B, \n", "cost estimates are not provided for best practice implementation. One coin indicates low cost (USD100 tCO2-eq–1 or USD200 ha–1). Thresholds in USD ha–1 are chosen to be \n", "comparable, but precise conversions will depend on the response option. Supporting evidence: Supporting evidence for the magnitude of the quantitative potential for \n", "land management-based response options can be found as follows: for mitigation Tables 6.13 to 6.20, with further evidence in Section 2.7.1; for adaptation Tables 6.21 \n", "to 6.28; for combating desertification Tables 6.29 to 6.36, with further evidence in Chapter 3; for combating degradation tables 6.37 to 6.44, with further evidence in \n", "Chapter 4; for enhancing food security Table’s 6.45 to 6.52, with further evidence in Chapter 5. Other synergies and trade-offs not shown here are discussed in Chapter 6. \n", "Additional supporting evidence for the qualitative assessments in the second row for each option in panel B can be found in the Table’s 6.6, 6.55, 6.56 and 6.58, Section \n", "6.3.5.1.3, and Box 6.1c.\n", "67\n", "Technical SummaryTSTS.7 Risk management and decision making \n", "in relation to sustainable development\n", "Increases in global mean surface temperature are projected \n", "to result in continued permafrost degradation and coastal \n", "degradation (high confidence), increased wildfire, decreased \n", "crop yields in low latitudes, decreased food stability, decreased \n", "water availability, vegetation loss (medium confidence), \n", "decreased access to food and increased soil erosion (low \n", "confidence). There is high agreement and high evidence that \n", "increases in global mean temperature will result in continued \n", "increase in global vegetation loss, coastal degradation, as \n", "well as decreased crop yields in low latitudes, decreased \n", "food stability, decreased access to food and nutrition, and \n", "medium confidence in continued permafrost degradation and \n", "water scarcity in drylands. Impacts are already observed across \n", "all components (high confidence). Some processes may experience \n", "irreversible impacts at lower levels of warming than others. There \n", "are high risks from permafrost degradation, and wildfire, coastal \n", "degradation, stability of food systems at 1.5°C while high risks from \n", "soil erosion, vegetation loss and changes in nutrition only occur \n", "at higher temperature thresholds due to increased possibility for \n", "adaptation (medium confidence). {7.2.2.1, 7.2.2.2, 7.2.2.3; 7.2.2.4; \n", "7.2.2.5; 7.2.2.6; 7.2.2.7; Figure 7.1} \n", "These changes result in compound risks to food systems, \n", "human and ecosystem health, livelihoods, the viability of \n", "infrastructure, and the value of land (high confidence). The \n", "experience and dynamics of risk change over time as a result of \n", "both human and natural processes (high confidence). There is high \n", "confidence that climate and land changes pose increased risks at \n", "certain periods of life (i.e. to the very young and ageing populations) \n", "as well as sustained risk to those living in poverty. Response options \n", "may also increase risks. For example, domestic efforts to insulate \n", "populations from food price spikes associated with climatic stressors \n", "in the mid-2000s inadequately prevented food insecurity and \n", "poverty, and worsened poverty globally. (Figure TS.14) {7.2.1, 7.2.2, \n", "7.3, Table 7.1}\n", "There is significant regional heterogeneity in risks: tropical \n", "regions, including Sub-Saharan Africa, Southeast Asia and \n", "Central and South America are particularly vulnerable to \n", "decreases in crop yield (high confidence). Yield of crops in \n", "higher latitudes may initially benefit from warming as well as from \n", "higher carbon dioxide (CO2) concentrations. But temperate zones, \n", "including the Mediterranean, North Africa, the Gobi desert, Korea \n", "and western United States are susceptible to disruptions from \n", "increased drought frequency and intensity, dust storms and fires \n", "(high confidence). {7.2.2}\n", "Risks related to land degradation, desertification and \n", "food security increase with temperature and can reverse \n", "development gains in some socio-economic development \n", "pathways (high confidence). SSP1 reduces the vulnerability \n", "and exposure of human and natural systems and thus limits \n", "risks resulting from desertification, land degradation and \n", "food insecurity compared to SSP3 (high confidence). SSP1 is characterized by low population growth, reduced inequalities, \n", "land-use regulation, low meat consumption, increased trade and \n", "few barriers to adaptation or mitigation. SSP3 has the opposite \n", "characteristics. Under SSP1, only a small fraction of the dryland \n", "population (around 3% at 3°C for the year 2050) will be exposed \n", "and vulnerable to water stress. However under SSP3, around 20% \n", "of dryland populations (for the year 2050) will be exposed and \n", "vulnerable to water stress by 1.5°C and 24% by 3°C. Similarly under \n", "SSP1, at 1.5°C, 2 million people are expected to be exposed and \n", "vulnerable to crop yield change. Over 20 million are exposed and \n", "vulnerable to crop yield change in SSP3, increasing to 854 million \n", "people at 3°C (low confidence). Livelihoods deteriorate as a result \n", "of these impacts, livelihood migration is accelerated, and strife and \n", "conflict is worsened (medium confidence). {Cross-Chapter Box 9 in \n", "Chapter 6, 7.2.2, 7.3.2, Table 7.1, Figure 7.2}\n", "Land-based adaptation and mitigation responses pose risks \n", "associated with the effectiveness and potential adverse side-\n", "effects of measures chosen (medium confidence). Adverse \n", "side-effects on food security, ecosystem services and water security \n", "increase with the scale of BECCS deployment. In a SSP1 future, \n", "bioenergy and BECCS deployment up to 4 million km2 is compatible \n", "with sustainability constraints, whereas risks are already high in \n", "a SSP3 future for this scale of deployment. {7.2.3}\n", "There is high confidence that policies addressing vicious \n", "cycles of poverty, land degradation and greenhouse gas \n", "(GHG) emissions implemented in a holistic manner can \n", "achieve climate-resilient sustainable development. Choice \n", "and implementation of policy instruments determine future \n", "climate and land pathways (medium confidence). Sustainable \n", "development pathways (described in SSP1) supported by effective \n", "regulation of land use to reduce environmental trade-offs, reduced \n", "reliance on traditional biomass, low growth in consumption and \n", "limited meat diets, moderate international trade with connected \n", "regional markets, and effective GHG mitigation instruments can \n", "result in lower food prices, fewer people affected by floods and other \n", "climatic disruptions, and increases in forested land (high agreement, \n", "limited evidence) (SSP1). A policy pathway with limited regulation \n", "of land use, low technology development, resource intensive \n", "consumption, constrained trade, and ineffective GHG mitigation \n", "instruments can result in food price increases, and significant loss \n", "of forest (high agreement, limited evidence) (SSP3). {3.7.5, 7.2.2, \n", "7.3.4, 7.5.5, 7.5.6, Table 7.1, Cross-Chapter Box 9 in Chapter 6, \n", "Cross-Chapter Box 12 in Chapter 7}\n", "Delaying deep mitigation in other sectors and shifting the \n", "burden to the land sector, increases the risk associated with \n", "adverse effects on food security and ecosystem services (high \n", "confidence). The consequences are an increased pressure on land \n", "with higher risk of mitigation failure and of temperature overshoot \n", "and a transfer of the burden of mitigation and unabated climate \n", "change to future generations. Prioritising early decarbonisation with \n", "minimal reliance on CDR decreases the risk of mitigation failure \n", "(high confidence). {2.5, 6.2, 6.4, 7.2.1, 7.2.2, 7.2.3, 7.5.6, 7.5.7, \n", "Cross-Chapter Box 9 in Chapter 6}\n", "68\n", "Technical Summary\n", "TSTrade-offs can occur between using land for climate mitigation \n", "or Sustainable Development Goal (SDG) 7 (affordable clean \n", "energy) with biodiversity, food, groundwater and riverine \n", "ecosystem services (medium confidence). There is medium \n", "confidence that trade-offs currently do not figure into climate policies \n", "and decision making. Small hydro power installations (especially in \n", "clusters) can impact downstream river ecological connectivity for \n", "fish (high agreement, medium evidence). Large scale solar farms \n", "and wind turbine installations can impact endangered species and \n", "disrupt habitat connectivity (medium agreement, medium evidence). \n", "Conversion of rivers for transportation can disrupt fisheries and \n", "endangered species (through dredging and traffic) (medium \n", "agreement, low evidence). {7.5.6}\n", "The full mitigation potential assessed in this report will \n", "only be realised if agricultural emissions are included in \n", "mainstream climate policy (high agreement, high evidence). \n", "Carbon markets are theoretically more cost-effective than taxation \n", "but challenging to implement in the land-sector (high confidence) \n", "Carbon pricing (through carbon markets or carbon taxes) has the \n", "potential to be an effective mechanism to reduce GHG emissions, \n", "although it remains relatively untested in agriculture and food \n", "systems. Equity considerations can be balanced by a mix of both \n", "market and non-market mechanisms (medium evidence, medium \n", "agreement). Emissions leakage could be reduced by multi-lateral \n", "action (high agreement, medium evidence). {7.4.6, 7.5.5, 7.5.6, Cross \n", "Chapter Box 9 in Chapter 6}\n", "A suite of coherent climate and land policies advances \n", "the goal of the Paris Agreement and the land-related SDG \n", "targets on poverty, hunger, health, sustainable cities and \n", "communities, responsible consumption and production, and \n", "life on land. There is high confidence that acting early will \n", "avert or minimise risks, reduce losses and generate returns \n", "on investment. The economic costs of action on sustainable land \n", "management (SLM), mitigation, and adaptation are less than the \n", "consequences of inaction for humans and ecosystems (medium \n", "confidence). Policy portfolios that make ecological restoration more \n", "attractive, people more resilient – expanding financial inclusion, \n", "flexible carbon credits, disaster risk and health insurance, social \n", "protection and adaptive safety nets, contingent finance and reserve \n", "funds, and universal access to early warning systems – could save \n", "100 billion USD a year, if implemented globally. {7.3.1, 7.4.7, 7.4.8, \n", "7.5.6, Cross-Chapter Box 10 in Chapter 7}\n", "Coordination of policy instruments across scales, levels, and \n", "sectors advances co-benefits, manages land and climate risks, \n", "advances food security, and addresses equity concerns (medium \n", "confidence). Flood resilience policies are mutually reinforcing \n", "and include flood zone mapping, financial incentives to move, and \n", "building restrictions, and insurance. Sustainability certification, \n", "technology transfer, land-use standards and secure land tenure \n", "schemes, integrated with early action and preparedness, advance \n", "response options. SLM improves with investment in agricultural \n", "research, environmental farm practices, agri-environmental payments, \n", "financial support for sustainable agricultural water infrastructure \n", "(including dugouts), agriculture emission trading, and elimination of agricultural subsidies (medium confidence). Drought resilience \n", "policies (including drought preparedness planning, early warning and \n", "monitoring, improving water use efficiency), synergistically improve \n", "agricultural producer livelihoods and foster SLM. (Figure TS.15) \n", "{3.7.5, Cross-Chapter Box 5 in Chapter 3, 7.4.3, 7.4.6, 7.5.6, 7.4.8, \n", "7.5.6, 7.6.3} \n", "Technology transfer in land use sectors offers new opportunities \n", "for adaptation, mitigation, international cooperation, R&D \n", "collaboration, and local engagement (medium confidence). \n", "International cooperation to modernise the traditional biomass \n", "sector will free up both land and labour for more productive uses. \n", "Technology transfer can assist the measurement and accounting \n", "of emission reductions by developing countries. {7.4.4, 7.4.6, \n", "Cross-Chapter Box 12 in Chapter 7} \n", "Measuring progress towards goals is important in decision-\n", "making and adaptive governance to create common \n", "understanding and advance policy effectiveness (high \n", "agreement, medium evidence). Measurable indicators, selected \n", "with the participation of people and supporting data collection, \n", "are useful for climate policy development and decision-making. \n", "Indicators include the SDGs, nationally determined contributions \n", "(NDCs), land degradation neutrality (LDN) core indicators, carbon \n", "stock measurement, measurement and monitoring for REDD+, \n", "metrics for measuring biodiversity and ecosystem services, and \n", "governance capacity. {7.5.5, 7.5.7, 7.6.4, 7.6.6} \n", "The complex spatial, cultural and temporal dynamics of risk \n", "and uncertainty in relation to land and climate interactions \n", "and food security, require a flexible, adaptive, iterative \n", "approach to assessing risks, revising decisions and policy \n", "instruments (high confidence). Adaptive, iterative decision-\n", "making moves beyond standard economic appraisal techniques \n", "to new methods such as dynamic adaptation pathways with risks \n", "identified by trigger points through indicators. Scenarios can provide \n", "valuable information at all planning stages in relation to land, climate \n", "and food; adaptive management addresses uncertainty in scenario \n", "planning with pathway choices made and reassessed to respond \n", "to new information and data as it becomes available. {3.7.5, 7.4.4, \n", "7.5.2, 7.5.3, 7.5.4, 7.5.7, 7.6.1, 7.6.3}\n", "ILK can play a key role in understanding climate processes \n", "and impacts, adaptation to climate change, SLM across \n", "different ecosystems, and enhancement of food security \n", "(high confidence). ILK is context-specific, collective, informally \n", "transmitted, and multi-functional, and can encompass factual \n", "information about the environment and guidance on management \n", "of resources and related rights and social behaviour. ILK can be \n", "used in decision-making at various scales and levels, and exchange \n", "of experiences with adaptation and mitigation that include ILK is \n", "both a requirement and an entry strategy for participatory climate \n", "communication and action. Opportunities exist for integration of ILK \n", "with scientific knowledge. {7.4.1, 7.4.5, 7.4.6, 7.6.4, Cross-Chapter \n", "Box 13 in Chapter 7}\n", "69Technical Summary\n", "TS\n", "Figure TS.14 | Risks to land-related human systems and ecosystems from global climate change, socio-economic development and mitigation choices. SPM approved draft IPCC SRCCL | Page 13 Subject to copy edit and layout1.5°5°\n", "4°\n", "3°\n", "2°\n", "1°2006–2015\n", "HMM\n", "HMM\n", "HMM\n", "HMM\n", "HMM\n", "MLL\n", "HM\n", "H\n", "Tropical crop\n", "yield declineFood \n", "supply instabilitiesDryland\n", "water scarcityVegetation\n", "lossWildfire\n", "damageSoil\n", "erosion Permafrost \n", "degradation\n", "Systems at risk:\n", "Food\n", "Livelihoods\n", "Value of land\n", "Human health\n", "Ecosystem health\n", "Infrastructure\n", "LLow\n", "Example HMMediumHHigh\n", "LLow\n", "Example HMMediumHHighSocio-economic choices can reduce or \n", "exacerbate climate related risks as well as \n", "influence the rate of temperature increase. \n", "The SSP1 pathway illustrates a world with \n", "low population growth, high income and \n", "reduced inequalities, food produced in \n", "low GHG emission systems, effective land \n", "use regulation and high adaptive capacity. \n", "The SSP3 pathway has the opposite \n", "trends. Risks are lower in SSP1 compar ed \n", "with SSP3 given the same level of \n", "GMST increase.Increases in global mean surface temperature (GMST), relative to pre-industrial levels, affect processes involved in desertification \n", "(water scarcity), land degradation (soil erosion, vegetation loss, wildfire, permafrost thaw) and food security (crop yield and food \n", "supply instabilities). Changes in these processes drive risks to food systems, livelihoods, infrastructure, the value of land, and human \n", "and ecosystem health. Changes in one process (e.g. wildfire or water scarcity) may result in compound risks. Risks are location-specific \n", "and differ by region.A. Risks to humans and ecosystems from changes in land-based processes as a result\n", "of climate change \n", "B. Different socioeconomic pathways affect levels of climate related risks\n", "GMST change \n", "relative to levels in pre-industrial time (°C)GMST change \n", "relative to levels in pre-industrial time (°C)GMST change \n", "relative to levels in pre-industrial time (°C)\n", "3°\n", "2°\n", "1°1.5°\n", "2006–2015 H HL\n", "MM\n", "HMM\n", "HMM\n", "MMM\n", "SSP1 SSP3 SSP1 SSP3 SSP1 SSP3Desertification Land degradation Food insecurity\n", "(water scarcity in drylands) (habitat degr., wildfire, floods) (availability, access)\n", "Legend: Level of impact/risk \n", "UndetectableModerateHighVery highLegend: Confidence\n", "level for\n", "transition Purple: Very high probability of severe impacts/ risks \n", "and the presence of significant irreversibility or the \n", "persistence of climate-related hazards, combined with \n", "limited ability to adapt due to the nature of the hazard \n", "or impacts/risks.\n", "Red: Significant and widespread impacts/risks.\n", "Yellow: Impacts/risks are detectable and attributable \n", "to climate change with at least medium confidence.\n", "White: Impacts/risks are undetectable. Risks\n", "Impacts5°\n", "4°\n", "3°\n", "2°\n", "1°\n", "Wildfire damageOver 100M \n", "people \n", "additionally \n", "exposedOver 50% \n", "increase in \n", "area burned in \n", "Mediterranean \n", "region\n", "Increase in fire \n", "weather season 5°\n", "4°\n", "3°\n", "2°\n", "1°HMM\n", "Food supply instabilitiesSustained food \n", "supply \n", "disruptions \n", "globally \n", "Infrequent \n", "price spikes \n", "affect \n", "individual \n", "countriesPeriodic food \n", "shocks across \n", "regions\n", "HMMIndicative example of transitions Indicative example of transitions\n", "70\n", "Technical Summary\n", "TSFigure TS.14 (continued): As in previous IPCC reports the literature was used to make expert judgements to assess the levels of global warming at which levels of \n", "risk are undetectable, moderate, high or very high, as described further in Chapter 7 and other parts of the underlying report. The figure indicates assessed risks at \n", "approximate warming levels which may be influenced by a variety of factors, including adaptation responses. The assessment considers adaptive capacity consistent \n", "with the SSP pathways as described below. Panel A: Risks to selected elements of the land system as a function of global mean surface temperature {2.1; Box 2.1; 3.5; \n", "3.7.1.1; 4.4.1.1; 4.4.1.2; 4.4.1.3; 5.2.2; 5.2.3; 5.2.4; 5.2.5; 7.2;7.3, Table SM7.1}. Links to broader systems are illustrative and not intended to be comprehensive. Risk \n", "levels are estimated assuming medium exposure and vulnerability driven by moderate trends in socioeconomic conditions broadly consistent with an SSP2 pathway. \n", "{Table SM7.4}. Panel B: Risks associated with desertification, land degradation and food security due to climate change and patterns of socio-economic development. \n", "Increasing risks associated with desertification include population exposed and vulnerable to water scarcity in drylands. Risks related to land degradation include \n", "increased habitat degradation, population exposed to wildfire and floods and costs of floods. Risks to food security include availability and access to food, including \n", "population at risk of hunger, food price increases and increases in disability adjusted life years attributable due to childhood underweight. Risks are assessed for two \n", "contrasted socio-economic pathways (SSP1 and SSP3 {SPM Box 1}) excluding the effects of targeted mitigation policies {3.5; 4.2.1.2; 5.2.2; 5.2.3; 5.2.4; 5.2.5; 6.1.4; 7.2, \n", "Table SM7.5}. Risks are not indicated beyond 3°C because SSP1 does not exceed this level of temperature change. All panels: As part of the assessment, literature was \n", "compiled and data extracted into a summary table. A formal expert elicitation protocol (based on modified-Delphi technique and the Sheffield Elicitation Framework), \n", "was followed to identify risk transition thresholds. This included a multi-round elicitation process with two rounds of independent anonymous threshold judgement, and \n", "a final consensus discussion. Further information on methods and underlying literature can be found in Chapter 7 Supplementary Material.\n", "Participation of people in land and climate decision making \n", "and policy formation allows for transparent effective solutions \n", "and the implementation of response options that advance \n", "synergies, reduce trade-offs in sustainable land management \n", "(high confidence), and overcomes barriers to adaptation and \n", "mitigation (high confidence). Improvements to sustainable land \n", "management are achieved by: (1) engaging people in citizen science \n", "by mediating and facilitating landscape conservation planning, policy \n", "choice, and early warning systems (medium confidence); (2) involving \n", "people in identifying problems (including species decline, habitat \n", "loss, land use change in agriculture, food production and forestry), \n", "selection of indicators, collection of climate data, land modelling, \n", "agricultural innovation opportunities. When social learning is \n", "combined with collective action, transformative change can occur \n", "addressing tenure issues and changing land use practices (medium \n", "confidence). Meaningful participation overcomes barriers by opening \n", "up policy and science surrounding climate and land decisions to \n", "inclusive discussion that promotes alternatives. {3.8.5, 7.5.1, 7.5.9; \n", "7.6.1, 7.6.4, 7.6.5, 7.6.7, 7.7.4, 7.7.6} \n", "Empowering women can bolster synergies among household \n", "food security and sustainable land management (high \n", "confidence). This can be achieved with policy instruments that \n", "account for gender differences. The overwhelming presence of \n", "women in many land-based activities including agriculture provides \n", "opportunities to mainstream gender policies, overcome gender \n", "barriers, enhance gender equality, and increase sustainable land \n", "management and food security (high confidence). Policies that \n", "address barriers include gender qualifying criteria and gender \n", "appropriate delivery, including access to financing, information, \n", "technology, government transfers, training, and extension may be \n", "built into existing women’s programs, structures (civil society groups) \n", "including collective micro enterprise (medium confidence). {Cross-\n", "Chapter Box 11 in Chapter 7} \n", "The significant social and political changes required for \n", "sustainable land use, reductions in demand and land-based \n", "mitigation efforts associated with climate stabilisation require \n", "a wide range of governance mechanisms. The expansion and \n", "diversification of land use and biomass systems and markets requires hybrid governance: public-private partnerships, transnational, \n", "polycentric, and state governance to insure opportunities are \n", "maximised, trade-offs are managed equitably, and negative impacts \n", "are minimised (medium confidence). {7.5.6, 7.7.2, 7.7.3, Cross-\n", "Chapter Box 7 in Chapter 6} \n", "Land tenure systems have implications for both adaptation \n", "and mitigation, which need to be understood within specific \n", "socio-economic and legal contexts, and may themselves \n", "be impacted by climate change and climate action (limited \n", "evidence, high agreement). Land policy (in a diversity of forms \n", "beyond focus on freehold title) can provide routes to land security \n", "and facilitate or constrain climate action, across cropping, rangeland, \n", "forest, fresh-water ecosystems and other systems. Large-scale land \n", "acquisitions are an important context for the relations between \n", "tenure security and climate change, but their scale, nature and \n", "implications are imperfectly understood. There is medium confidence \n", "that land titling and recognition programs, particularly those that \n", "authorise and respect indigenous and communal tenure, can lead \n", "to improved management of forests, including for carbon storage. \n", "Strong public coordination (government and public administration) \n", "can integrate land policy with national policies on adaptation and \n", "reduce sensitivities to climate change. {7.7.2; 7.7.3; 7.7.4, 7.7.5} \n", "Significant gaps in knowledge exist when it comes to \n", "understanding the effectiveness of policy instruments and \n", "institutions related to land use management, forestry, \n", "agriculture and bioenergy. Interdisciplinary research is needed \n", "on the impacts of policies and measures in land sectors. Knowledge \n", "gaps are due in part to the highly contextual and local nature of \n", "land and climate measures and the long time periods needed to \n", "evaluate land use change in its socio-economic frame, as compared \n", "to technological investments in energy or industry that are somewhat \n", "more comparable. Significant investment is needed in monitoring, \n", "evaluation and assessment of policy impacts across different sectors \n", "and levels. {7.8}\n", "71\n", "Technical SummaryTSTable TS.1 | Selection of Policies/Programmes/Instruments that support response options.\n", "Category Intergrated Response Option Policy instrument supporting response option\n", "Land management \n", "in agricultureIncreased food productivityInvestment in agricultural research for crop and livestock improvement, agricultural technology transfer, \n", "inland capture fisheries and aquaculture {7.4.7} agricultural policy reform and trade liberalisation\n", "Improved cropland, grazing and livestock \n", "managementEnvironmental farm programs/agri-environment schemes, water efficiency requirements and water \n", "transfer {3.8.5}, extension services\n", "Agroforestry Payment for ecosystem services (ES) {7.4.6}\n", "Agricultural diversificationElimination of agriculture subsidies {5.7.1}, environmental farm programs, agri-environmental payments \n", "{7.5.6}, rural development programmes\n", "Reduced grassland conversion to cropland Elimination of agriculture subsidies, remove insurance incentives, ecological restoration {7.4.6}\n", "Integrated water management Integrated governance {7.6.2}, multi-level instruments [7.4.1}\n", "Land management \n", "in forestsForest management, reduced deforestation and \n", "degradation, reforestation and forest restora-\n", "tion, afforestationREDD+, forest conservation regulations, payments for ES, recognition of forest rights and land tenure \n", "{7.4.6}, adaptive management of forests {7.5.4}, land-use moratoriums, reforestation programmes and \n", "investment {4.9.1}\n", "Land management \n", "of soilsIncreased soil organic carbon content, reduced \n", "soil erosion, reduced soil salinisation, reduced \n", "soil compaction, biochar addition to soilLand degradation neutrality (LDN) {7.4.5}, drought plans, flood plans, flood zone mapping {7.4.3}, \n", "technology transfer (7.4.4}, land-use zoning {7.4.6}, ecological service mapping and stakeholder-based \n", "quantification {7.5.3}, environmental farm programmes/agri-environment schemes, water-efficiency \n", "requirements and water transfer {3.7.5}\n", "Land management \n", "in all other ecosys-\n", "temsFire management Fire suppression, prescribed fire management, mechanical treatments {7.4.3}\n", "Reduced landslides and natural hazards Land-use zoning {7.4.6}\n", "Reduced pollution – acidification Environmental regulations, climate mitigation (carbon pricing) {7.4.4}\n", "Management of invasive species/ encroachment Invasive species regulations, trade regulations {5.7.2, 7.4.6}\n", "Restoration and reduced conversion of coastal \n", "wetlandsFlood zone mapping {7.4.3}, land-use zoning {7.4.6}\n", "Restoration and reduced conversion of \n", "peatlandsPayment for ES {7.4.6; 7.5.3}, standards and certification programmes {7.4.6}, land-use moratoriums\n", "Biodiversity conservation Conservation regulations, protected areas policies\n", "Carbon dioxide \n", "removal (CDR) land \n", "managementEnhanced weathering of minerals No data\n", "Bioenergy and bioenergy with carbon capture \n", "and storage (BECCS)Standards and certification for sustainability of biomass and land use {7.4.6}\n", "Demand \n", "managementDietary changeAwareness campaigns/education, changing food choices through nudges, synergies with health insur -\n", "ance and policy {5.7.2}\n", "Reduced post-harvest losses\n", "Reduced food waste (consumer or retailer), \n", "material substitutionAgricultural business risk programmes {7.4.8}; regulations to reduce and taxes on food waste, improved \n", "shelf life, circularising the economy to produce substitute goods, carbon pricing, sugar/fat taxes {5.7.2}\n", "Supply \n", "managementSustainable sourcingFood labelling, innovation to switch to food with lower environmental footprint, public procurement \n", "policies {5.7.2}, standards and certification programmes {7.4.6}\n", "Management of supply chainsLiberalised international trade {5.7.2}, food purchasing and storage policies of governments, standards \n", "and certification programmes {7.4.6}, regulations on speculation in food systems\n", "Enhanced urban food systemsBuy local policies; land-use zoning to encourage urban agriculture, nature-based solutions and green \n", "infrastructure in cities; incentives for technologies like vertical farming\n", "Improved food processing and retailing, \n", "improved energy use in food systems Agriculture emission trading {7.4.4}; investment in R&D for new technologies; certification\n", "Risk managementManagement of urban sprawl Land-use zoning {7.4.6}\n", "Livelihood diversification Climate-smart agriculture policies, adaptation policies, extension services {7.5.6}\n", "Disaster risk management Disaster risk reduction {7.5.4; 7.4.3}, adaptation planning\n", "Risk-sharing instrumentsInsurance, iterative risk management, CAT bonds, risk layering, contingency funds {7.4.3}, agriculture \n", "business risk portfolios {7.4.8}\n", "72Technical Summary\n", "TS\n", "Figure TS.15 | Pathways linking socioeconomic development, mitigation responses and land (Panel A).\n", "SPM approved draft IPCC SRCCL | Page 36 Subject to copy edit and layout-1010\n", "7.5\n", "5\n", "2.5\n", "0\n", "-2.5\n", "-5\n", "-7.5\n", "-1010\n", "7.5\n", "5\n", "2.5\n", "0\n", "-2.5\n", "-5\n", "-7.5\n", "-1010\n", "7.5\n", "5\n", "2.5\n", "0\n", "-2.5\n", "-5\n", "-7.5\n", "2025 2050 2075 2100 2010 2025 2050 2075 2100 2010 2025 2050 2075 2100 2010C\n", "PNLBCF\n", "C\n", "PNLBC\n", "C\n", "PNLBC\n", "F\n", "FA. Sustainability-focused (SSP1)\n", "Sustainability in land management, \n", "agricultural intensification, production \n", "and consumption patterns result in \n", "reduced need for agricultural land, \n", "despite increases in per capita food \n", "consumption. This land can instead be \n", "used for reforestation, afforestation, \n", "and bioenergy.B. Middle of the road (SSP2 )\n", "Societal as well as technological \n", "development follows historical patterns. \n", "Increased demand for land mitigation \n", "options such as bioenergy, reduced \n", "deforestation or afforestation decreases \n", "availability of agricultural land for food, \n", "feed and fibre.Socioeconomic development and land management influence the evolution of the land system including the relative amount of land \n", "allocated to /C.s/R.s/O.s/P.s/L.s/A.s/N.s/D.s, /P.s/A.s/S.s/T.s/U.s/R.s/E.s, /B.s/I.s/O.s/E.s/N.s/E.s/R.s/G.s/Y.s /C.s/R.s/O.s/P.s/L.s/A.s/N.s/D.s, /F.s/O.s/R.s/E.s/S.s/T.s, and /N.s/A.s/T.s/U.s/R.s/A.s/L.s /L.s/A.s/N.s/D.s. The lines show the median across Integrated \n", "Assessment Models (IAMs) for three alternative shared socioeconomic pathways (SSP1, SSP2 and SSP5 at RCP1.9); shaded areas show \n", "the range across models. Note that pathways illustrate the effects of climate change mitigation but not those of climate change impacts \n", "or adaptation.A. Pathways linking socioeconomic development, mitigation responses and land\n", "C. Resource intensive (SSP5)\n", "Resource-intensive production and \n", "consumption patterns, results in high \n", "baseline emissions. Mitigation focuses \n", "on technological solutions including \n", "substantial bioenergy and BECCS . \n", "Intensification and competing land uses \n", "contribute to declines in agricultural land. \n", "/C.s/R.s/O.s/P.s/L.s/A.s/N.s/D.s /P.s/A.s/S.s/T.s/U.s/R.s/E.s /B.s/I.s/O.s/E.s/N.s/E.s/R.s/G.s/Y.s /C.s/R.s/O.s/P.s/L.s/A.s/N.s/D.s /F.s/O.s/R.s/E.s/S.s/T.s /N.s/A.s/T.s/U.s/R.s/A.s/L.s /L.s/A.s/N.s/D.sSSP1 Sustainability-focused\n", "Change in Land from 2010 (Mkm/two.numr)SSP2 Middle of the road\n", "Change in Land from 2010 (Mkm/two.numr)SSP5 Resource intensive\n", "Change in Land from 2010 (Mkm/two.numr)\n", "73\n", "Technical SummaryTS\n", "SPM approved draft IPCC SRCCL | Page 37 Subject to copy edit and layoutSSP1Change in Pasture\n", "from 2010\n", "Mkm/two.numr Change in Forest\n", "from 2010\n", "Mkm/two.numr Change in Cropland\n", "from 2010\n", "Mkm/two.numr Change in Bioenergy\n", "Cropland from 2010 \n", "Mkm/two.numr Change in Natural\n", "Land from 2010\n", "Mkm/two.numrB. Land use and land cover change in the SSPs \n", "0.5 ( -4.9 , 1 )\n", "0 ( -7.3 , 7.1 )\n", "-0.9 ( -2.2 , 1.5 )\n", "0.2 ( -3.5 , 1.1 )\n", "0.5 ( -1 , 1.7 )\n", "1.8 ( -1.7 , 6 )\n", "0.3 ( -1.1 , 1.8 )\n", "3.3 ( -0.3 , 5.9 )5/5\n", "5/5\n", "5/5\n", "5/52.1 ( 0.9 , 5 )\n", "4.3 ( 1.5 , 7.2 )\n", "1.3 ( 0.4 , 1.9 )\n", "5.1 ( 1.6 , 6.3 )\n", "0.8 ( 0.5 , 1.3 )\n", "1.9 ( 1.4 , 3.7 )\n", "0.5 ( 0.2 , 1.4 )\n", "1.8 ( 1.4 , 2.4 )RCP1.9 in 2050\n", "2100\n", "RCP2.6 in 2050\n", " 2100\n", "RCP4.5 in 2050\n", "2100\n", "Baseline in 2050\n", " 2100-1.2 ( -4.6 , -0.3 )\n", "-5.2 ( -7.6 , -1.8 )\n", "-1 ( -4.7 , 1 )\n", "-3.2 ( -7.7 , -1.8 )\n", "0.1 ( -3.2 , 1.5 )\n", "-2.3 ( -6.4 , -1.6 )\n", "0.2 ( -1.6 , 1.9 )\n", "-1.5 ( -5.7 , -0.9 )3.4 ( -0.1 , 9.4 )\n", "7.5 ( 0.4 , 15.8 )\n", "2.6 ( -0.1 , 8.4 )\n", "6.6 ( -0.1 , 10.5 )\n", "0.6 ( -0.7 , 4.2 )\n", "3.9 ( 0.2 , 8.8 )\n", "-0.1 ( -0.8 , 1.1 )\n", "0.9 ( 0.3 , 3 )-4.1 ( -5.6 , -2.5 )\n", "-6.5 ( -12.2 , -4.8 )\n", "-3 ( -4 , -2.4 )\n", "-5.5 ( -9.9 , -4.2 )\n", "-2.4 ( -3.3 , -0.9 )\n", "-4.6 ( -7.3 , -2.7 )\n", "-1.5 ( -2.9 , -0.2 )\n", "-2.1 ( -7 , 0 )Quantitative indicators\n", "for the SSPsCount of\n", "models\n", "included*\n", "SSP2-2.2 ( -7 , 0.6 )\n", "-2.3 ( -9.6 , 2.7 )\n", "-3.2 ( -4.2 , 0.1 )\n", "-5.2 ( -7.2 , 0.5 )\n", "-2.2 ( -2.2 , 0.7 )\n", "-3.4 ( -4.7 , 1.5 )\n", "-1.5 ( -2.6 , -0.2 )\n", "-2.1 ( -5.9 , 0.3 )4/5\n", "5/5\n", "5/5\n", "5/54.5 ( 2.1 , 7 )\n", "6.6 ( 3.6 , 11 )\n", "2.2 ( 1.7 , 4.7 )\n", "6.9 ( 2.3 , 10.8 )\n", "1.5 ( 0.1 , 2.1 )\n", "4.1 ( 0.4 , 6.3 )\n", "0.7 ( 0 , 1.5 )\n", "1.2 ( 0.1 , 2.4 )RCP1.9 in 2050\n", "2100\n", "RCP2.6 in 2050\n", " 2100\n", "RCP4.5 in 2050\n", "2100\n", "Baseline in 2050\n", " 2100-1.2 ( -2 , 0.3 )\n", "-2.9 ( -4 , 0.1 )\n", "0.6 ( -1.9 , 1.9 )\n", "-1.4 ( -4 , 0.8 )\n", "1.2 ( -0.9 , 2.7 )\n", "0.7 ( -2.6 , 3.1 )\n", "1.3 ( 1 , 2.7 )\n", "1.9 ( 0.8 , 2.8 )3.4 ( -0.9 , 7 )\n", "6.4 ( -0.8 , 9.5 )\n", "1.6 ( -0.9 , 4.2 )\n", "5.6 ( -0.9 , 5.9 )\n", "-0.9 ( -2.5 , 2.9 )\n", "-0.5 ( -3.1 , 5.9 )\n", "-1.3 ( -2.5 , -0.4 )\n", "-1.3 ( -2.7 , -0.2 )-4.8 ( -6.2 , -0.4 )\n", "-7.6 ( -11.7 , -1.3 )\n", "-1.4 ( -3.7 , 0.4 )\n", "-7.2 ( -8 , 0.5 )\n", "-0.1 ( -2.5 , 1.6 )\n", "-2.8 ( -5.3 , 1.9 )\n", "-0.1 ( -1.2 , 1.6 )\n", "-0.2 ( -1.9 , 2.1 )\n", "SSP3-3.4 ( -4.4 , -2 )\n", "-6.2 ( -6.8 , -5.4 )\n", "-3 ( -4.6 , -1.7 )\n", "-5 ( -7.1 , -4.2 )3/3\n", "4/4-\n", "-\n", "-\n", "-\n", "1.3 ( 1.3 , 2 )\n", "4.6 ( 1.5 , 7.1 )\n", "1 ( 0.2 , 1.5 )\n", "1.1 ( 0.9 , 2.5 )RCP1.9 in 2050\n", "2100\n", "RCP2.6 in 2050\n", " 2100\n", "RCP4.5 in 2050\n", "2100\n", "Baseline in 2050\n", " 2100-\n", "-\n", "-\n", "-\n", "2.3 ( 1.2 , 3 )\n", "3.4 ( 1.9 , 4.5 )\n", "2.5 ( 1.5 , 3 )\n", "5.1 ( 3.8 , 6.1 )-\n", "-\n", "-\n", "-\n", "-2.4 ( -4 , -1 )\n", "-3.1 ( -5.5 , -0.3 )\n", "-2.5 ( -4 , -1.5 )\n", "-5.3 ( -6 , -2.6 )-\n", "-\n", "-\n", "-\n", "2.1 ( -0.1 , 3.8 )\n", "2 ( -2.5 , 4.4 )\n", "2.4 ( 0.6 , 3.8 )\n", "3.4 ( 0.9 , 6.4 )\n", "SSP4-4.5 ( -6 , -2.1 )\n", "-5.8 ( -10.2 , -4.7 )\n", "-2.7 ( -4.4 , -0.4 )\n", "-2.8 ( -7.8 , -2 )\n", "-2.8 ( -2.9 , -0.2 )\n", "-2.4 ( -5 , -1 )3/3\n", "3/3\n", "3/3-\n", "-\n", "3.3 ( 1.5 , 4.5 )\n", "2.5 ( 2.3 , 15.2 )\n", "1.7 ( 1 , 1.9 )\n", "2.7 ( 2.3 , 4.7 )\n", "1.1 ( 0.7 , 2 )\n", "1.7 ( 1.4 , 2.6 )RCP1.9 in 2050\n", "2100\n", "RCP2.6 in 2050\n", " 2100\n", "RCP4.5 in 2050\n", "2100\n", "Baseline in 2050\n", " 2100-\n", "-\n", "0.5 ( -0.1 , 0.9 )\n", "-0.8 ( -0.8 , 1.8 )\n", "1.1 ( -0.1 , 1.7 )\n", "1.1 ( 0.2 , 1.2 )\n", "1.1 ( 0.7 , 1.8 )\n", "1.2 ( 1.2 , 1.9 )-\n", "-\n", "0.7 ( -0.3 , 2.2 )\n", "1.4 ( -1.7 , 4.1 )\n", "-1.8 ( -2.3 , 2.1 )\n", "-0.7 ( -2.6 , 1 )\n", "-1.8 ( -2.3 , -1 )\n", "-2.4 ( -2.5 , -2 )-\n", "-\n", "-0.6 ( -0.7 , 0.1 )\n", "-1.2 ( -2.5 , -0.2 )\n", "0.8 ( -0.5 , 1.5 )\n", "1.4 ( -1 , 1.8 )\n", "1.5 ( -0.5 , 2.1 )\n", "1.3 ( -1 , 4.4 )\n", "SSP5-1.5 ( -3.9 , 0.9 )\n", "-0.5 ( -4.2 , 3.2 )\n", "-3.4 ( -6.9 , 0.3 )\n", "-4.3 ( -8.4 , 0.5 )\n", "-2.5 ( -3.7 , 0.2 )\n", "-4.1 ( -4.6 , 0.7 )\n", "-0.6 ( -3.8 , 0.4 )\n", "-0.2 ( -2.4 , 1.8 )2/4\n", "4/4\n", "4/4\n", "4/46.7 ( 6.2 , 7.2 )\n", "7.6 ( 7.2 , 8 )\n", "4.8 ( 3.8 , 5.1 )\n", "9.1 ( 7.7 , 9.2 )\n", "1.7 ( 0.6 , 2.9 )\n", "4.8 ( 2 , 8 )\n", "0.8 ( 0 , 2.1 )\n", "1 ( 0.2 , 2.3 )RCP1.9 in 2050\n", "2100\n", "RCP2.6 in 2050\n", " 2100\n", "RCP4.5 in 2050\n", "2100\n", "Baseline in 2050\n", " 2100-1.9 ( -3.5 , -0.4 )\n", "-3.4 ( -6.2 , -0.5 )\n", "-2.1 ( -4 , 1 )\n", "-3.3 ( -6.5 , -0.5 )\n", "0.6 ( -3.3 , 1.9 )\n", "-1 ( -5.5 , 1 )\n", "1.5 ( -0.7 , 3.3 )\n", "1 ( -2 , 2.5 )3.1 ( -0.1 , 6.3 )\n", "4.7 ( 0.1 , 9.4 )\n", "3.9 ( -0.1 , 6.7 )\n", "3.9 ( -0.1 , 9.3 )\n", "-0.1 ( -1.7 , 6 )\n", "-0.2 ( -1.4 , 9.1 )\n", "-1.9 ( -3.4 , 0.5 )\n", "-2.1 ( -3.4 , 1.1 )-6.4 ( -7.7 , -5.1 )\n", "-8.5 ( -10.7 , -6.2 )\n", "-4.4 ( -5 , 0.2 )\n", "-6.3 ( -9.1 , -1.4 )\n", "-1.2 ( -2.6 , 2.3 )\n", "-3 ( -5.2 , 2.1 )\n", "-0.1 ( -1.5 , 2.9 )\n", "-0.4 ( -2.4 , 2.8 )Infeasible in all assessed models\n", "* Count of models included / Count of models attempted. One model did not provide land data and is excluded from all entries.\n", "** One model could reach RCP1.9 with SSP4, but did not provide land data.Infeasible in all assessed models\n", "Infeasible in all assessed models**\n", "Figure TS.15 | Pathways linking socioeconomic development, mitigation responses and land (Panel B).\n", "74\n", "Technical Summary\n", "TSFigure TS.15 (continued): Future scenarios provide a framework for understanding the implications of mitigation and socioeconomics on land. The SSPs span a range \n", "of different socioeconomic assumptions (Box SPM.1). They are combined with Representative Concentration Pathways (RCPs)2 which imply different levels of mitigation. \n", "The changes in cropland, pasture, bioenergy cropland, forest, and natural land from 2010 are shown. For this Figure, Cropland includes all land in food, feed, and fodder \n", "crops, as well as other arable land (cultivated area). This category includes first generation non-forest bioenergy crops (e.g., corn for ethanol, sugar cane for ethanol, \n", "soybeans for biodiesel), but excludes second generation bioenergy crops. Pasture includes categories of pasture land, not only high-quality rangeland, and is based on \n", "FAO definition of ‘permanent meadows and pastures’. Bioenergy cropland includes land dedicated to second generation energy crops (e.g., switchgrass, miscanthus, \n", "fast-growing wood species). Forest includes managed and unmanaged forest. Natural land includes other grassland, savannah, and shrubland. Panel A: This panel shows \n", "integrated assessment model (IAM)3 results for SSP1, SSP2 and SSP5 at RCP1.9.4 For each pathway, the shaded areas show the range across all IAMs; the line indicates \n", "the median across models. For RCP1.9, SSP1, SSP2 and SSP5 results are from five, four and two IAMs respectively. Panel B: Land use and land cover change are indicated \n", "for various SSP-RCP combinations, showing multi-model median and range (min, max). (Box SPM.1) {1.3.2, 2.7.2, 6.1, 6.4.4, 7.4.2, 7.4.4, 7.4.5, 7.4.6, 7.4.7, 7.4.8, 7.5.3, \n", "7.5.6, Cross-Chapter Box 1 in Chapter 1, Cross-Chapter Box 9 in Chapter 6}\n", "2 Representative Concentration Pathways (RCPs) are scenarios that include timeseries of emissions and concentrations of the full suite of GHGs and aerosols and chemically active \n", " gases, as well as land use/land cover.\n", "3 Integrated Assessment Models (IAMs) integrate knowledge from two or more domains into a single framework. In this figure, IAMs are used to assess linkages between economic, \n", " social and technological development and the evolution of the climate system.\n", "4 The RCP1.9 pathways assessed in this report have a 66% chance of limiting warming to 1.5°C in 2100, but some of these pathways overshoot 1.5°C of warming during the 21st century by >0.1°C.\n", "Summary for Policymakers\n", "\n", "SPM3SPM\n", "Drafting Authors:\n", "Myles Allen (UK), Mustafa Babiker (Sudan), Yang Chen (China), Heleen de Coninck \n", "(Netherlands/EU), Sarah Connors (UK), Renée van Diemen (Netherlands), Opha Pauline \n", "Dube (Botswana), Kristie L. Ebi (USA), Francois Engelbrecht (South Africa), Marion Ferrat \n", "(UK/France), James Ford (UK/Canada), Piers Forster (UK), Sabine Fuss (Germany), Tania \n", "Guillén Bolaños (Germany/Nicaragua), Jordan Harold (UK), Ove Hoegh-Guldberg (Australia), \n", "Jean-Charles Hourcade (France), Daniel Huppmann (Austria), Daniela Jacob (Germany), \n", "Kejun Jiang (China), Tom Gabriel Johansen (Norway), Mikiko Kainuma (Japan), Kiane de \n", "Kleijne (Netherlands/EU), Elmar Kriegler (Germany), Debora Ley (Guatemala/Mexico), \n", "Diana Liverman (USA), Natalie Mahowald (USA), Valérie Masson-Delmotte (France), \n", "J. B. Robin Matthews (UK), Richard Millar (UK), Katja Mintenbeck (Germany), Angela Morelli \n", "(Norway/Italy), Wilfran Moufouma-Okia (France/Congo), Luis Mundaca (Sweden/Chile), \n", "Maike Nicolai (Germany), Chukwumerije Okereke (UK/Nigeria), Minal Pathak (India), Antony \n", "Payne (UK), Roz Pidcock (UK), Anna Pirani (Italy), Elvira Poloczanska (UK/Australia), Hans-\n", "Otto Pörtner (Germany), Aromar Revi (India), Keywan Riahi (Austria), Debra C. Roberts \n", "(South Africa), Joeri Rogelj (Austria/Belgium), Joyashree Roy (India), Sonia I. Seneviratne \n", "(Switzerland), Priyadarshi R. Shukla (India), James Skea (UK), Raphael Slade (UK), Drew \n", "Shindell (USA), Chandni Singh (India), William Solecki (USA), Linda Steg (Netherlands), \n", "Michael Taylor (Jamaica), Petra Tschakert (Australia/Austria), Henri Waisman (France), \n", "Rachel Warren (UK), Panmao Zhai (China), Kirsten Zickfeld (Canada).\n", "This Summary for Policymakers should be cited as:\n", "IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts \n", "of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, \n", "in the context of strengthening the global response to the threat of climate change, sustainable development, \n", "and efforts to eradicate poverty [Masson-Delmotte, V., P . Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P .R. Shukla, \n", "A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y . Chen, X. Zhou, M.I. Gomis, \n", "E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. Cambridge University Press, Cambridge, UK and New \n", "York, NY , USA, pp. 3-24. https://doi.org/10.1017/9781009157940.001.Summary \n", "for Policymakers SPM\n", "SPMSummary for Policymakers4Introduction\n", "This Report responds to the invitation for IPCC ‘... to provide a Special Report in 2018 on the impacts of global warming of 1.5°C \n", "above pre-industrial levels and related global greenhouse gas emission pathways’ contained in the Decision of the 21st Conference \n", "of Parties of the United Nations Framework Convention on Climate Change to adopt the Paris Agreement.1\n", "The IPCC accepted the invitation in April 2016, deciding to prepare this Special Report on the impacts of global warming of \n", "1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global \n", "response to the threat of climate change, sustainable development, and efforts to eradicate poverty.\n", "This Summary for Policymakers (SPM) presents the key findings of the Special Report, based on the assessment of the available \n", "scientific, technical and socio-economic literature2 relevant to global warming of 1.5°C and for the comparison between global \n", "warming of 1.5°C and 2°C above pre-industrial levels. The level of confidence associated with each key finding is reported using \n", "the IPCC calibrated language.3 The underlying scientific basis of each key finding is indicated by references provided to chapter \n", "elements. In the SPM, knowledge gaps are identified associated with the underlying chapters of the Report.\n", "A. Understanding Global Warming of 1.5°C4\n", "A.1 Human activities are estimated to have caused approximately 1.0°C of global warming5 above \n", "pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C \n", "between 2030 and 2052 if it continues to increase at the current rate. (high confidence) (Figure \n", "SPM.1) {1.2}\n", "A.1.1 Reflecting the long-term warming trend since pre-industrial times, observed global mean surface temperature (GMST) for \n", "the decade 2006–2015 was 0.87°C (likely between 0.75°C and 0.99°C)6 higher than the average over the 1850–1900 \n", "period (very high confidence). Estimated anthropogenic global warming matches the level of observed warming to within \n", "±20% (likely range). Estimated anthropogenic global warming is currently increasing at 0.2°C (likely between 0.1°C and \n", "0.3°C) per decade due to past and ongoing emissions (high confidence). {1.2.1, Table 1.1, 1.2.4}\n", "A.1.2 Warming greater than the global annual average is being experienced in many land regions and seasons, including two to \n", "three times higher in the Arctic. Warming is generally higher over land than over the ocean. (high confidence) {1.2.1, 1.2.2, \n", "Figure 1.1, Figure 1.3, 3.3.1, 3.3.2}\n", "A.1.3 Trends in intensity and frequency of some climate and weather extremes have been detected over time spans during which \n", "about 0.5°C of global warming occurred (medium confidence). This assessment is based on several lines of evidence, \n", "including attribution studies for changes in extremes since 1950. {3.3.1, 3.3.2, 3.3.3} \n", "1 Decision 1/CP .21, paragraph 21.\n", "2 The assessment covers literature accepted for publication by 15 May 2018.\n", "3 Each finding is grounded in an evaluation of underlying evidence and agreement. A level of confidence is expressed using five qualifiers: very low, low, medium, high and very high, and \n", " typeset in italics, for example, medium confidence. The following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% \n", " probability, very likely 90–100%, likely 66–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely \n", " 95–100%, more likely than not >50–100%, more unlikely than likely 0–<50%, extremely unlikely 0–5%) may also be used when appropriate. Assessed likelihood is typeset in italics, \n", " for example, very likely. This is consistent with AR5. \n", "4 See also Box SPM.1: Core Concepts Central to this Special Report.\n", "5 Present level of global warming is defined as the average of a 30-year period centred on 2017 assuming the recent rate of warming continues.\n", "6 This range spans the four available peer-reviewed estimates of the observed GMST change and also accounts for additional uncertainty due to possible short-term natural variability. \n", " {1.2.1, Table 1.1}\n", "SPM Summary for Policymakers5A.2 Warming from anthropogenic emissions from the pre-industrial period to the present will persist for \n", "centuries to millennia and will continue to cause further long-term changes in the climate system, \n", "such as sea level rise, with associated impacts (high confidence), but these emissions alone are \n", "unlikely to cause global warming of 1.5°C (medium confidence). (Figure SPM.1) {1.2, 3.3, Figure 1.5}\n", "A.2.1 Anthropogenic emissions (including greenhouse gases, aerosols and their precursors) up to the present are unlikely to \n", "cause further warming of more than 0.5°C over the next two to three decades (high confidence) or on a century time scale \n", "(medium confidence). {1.2.4, Figure 1.5}\n", "A.2.2 Reaching and sustaining net zero global anthropogenic CO2 emissions and declining net non-CO2 radiative forcing would \n", "halt anthropogenic global warming on multi-decadal time scales (high confidence). The maximum temperature reached is \n", "then determined by cumulative net global anthropogenic CO2 emissions up to the time of net zero CO2 emissions (high \n", "confidence) and the level of non-CO2 radiative forcing in the decades prior to the time that maximum temperatures are \n", "reached (medium confidence). On longer time scales, sustained net negative global anthropogenic CO2 emissions and/\n", "or further reductions in non-CO2 radiative forcing may still be required to prevent further warming due to Earth system \n", "feedbacks and to reverse ocean acidification (medium confidence) and will be required to minimize sea level rise (high \n", "confidence). {Cross-Chapter Box 2 in Chapter 1, 1.2.3, 1.2.4, Figure 1.4, 2.2.1, 2.2.2, 3.4.4.8, 3.4.5.1, 3.6.3.2}\n", "A.3 Climate-related risks for natural and human systems are higher for global warming of 1.5°C than \n", "at present, but lower than at 2°C (high confidence). These risks depend on the magnitude and rate \n", "of warming, geographic location, levels of development and vulnerability, and on the choices and \n", "implementation of adaptation and mitigation options (high confidence). (Figure SPM.2) {1.3, 3.3, \n", "3.4, 5.6}\n", "A.3.1 Impacts on natural and human systems from global warming have already been observed (high confidence). Many land and \n", "ocean ecosystems and some of the services they provide have already changed due to global warming (high confidence). \n", "(Figure SPM.2) {1.4, 3.4, 3.5}\n", "A.3.2 Future climate-related risks depend on the rate, peak and duration of warming. In the aggregate, they are larger if global \n", "warming exceeds 1.5°C before returning to that level by 2100 than if global warming gradually stabilizes at 1.5°C, especially \n", "if the peak temperature is high (e.g., about 2°C) (high confidence). Some impacts may be long-lasting or irreversible, such \n", "as the loss of some ecosystems (high confidence). {3.2, 3.4.4, 3.6.3, Cross-Chapter Box 8 in Chapter 3}\n", "A.3.3 Adaptation and mitigation are already occurring (high confidence). Future climate-related risks would be reduced by the \n", "upscaling and acceleration of far-reaching, multilevel and cross-sectoral climate mitigation and by both incremental and \n", "transformational adaptation (high confidence). {1.2, 1.3, Table 3.5, 4.2.2, Cross-Chapter Box 9 in Chapter 4, Box 4.2, Box \n", "4.3, Box 4.6, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.4.1, 4.4.4, 4.4.5, 4.5.3} \n", "SPMSummary for Policymakers660\n", "503 000\n", "2 000\n", "1 00040\n", "30\n", "20\n", "10\n", "0 03\n", "2\n", "1\n", "0Cumulative emissions of CO/two.dnom and future non-CO/two.dnom radiative forcing determine \n", "the probability of limiting warming to 1.5°C\n", "Billion tonnes CO/two.dnom per year (GtCO/two.dnom/yr) Billion tonnes CO/two.dnom (GtCO/two.dnom) Watts per square metre (W/m/two.numr)b) Stylized net global CO/two.dnom emission pathways d) Non-CO/two.dnom radiative forcing pathways c) Cumulative net CO/two.dnom emissionsa) Observed global temperature change and modeled \n", "responses to stylized anthropogenic emission and forcing pathways\n", "Observed monthly global \n", "mean surface temperature\n", "Estimated anthropogenic \n", "warming to date and \n", "likely range\n", "Faster immediate CO/two.dnom emission reductions \n", "limit cumulative CO/two.dnom emissions shown in \n", "panel (c).Maximum temperature rise is determined by cumulative net CO/two.dnom emissions and net non-CO/two.dnom \n", "radiative forcing due to methane, nitrous oxide, aerosols and other anthropogenic forcing agents.Global warming relative to 1850-1900 (°C)\n", "Cumulative CO/two.dnom \n", "emissions in pathways \n", "reaching net zero in \n", "2055 and 2040Non-CO/two.dnom radiative forcing \n", "reduced a/f_ter 2030 or \n", "not reduced a/f_ter 20301960\n", "1980 2020 2060 2100 1980 2020 2060 2100 1980 2020 2060 21001980 2000 20202017\n", "2040 2060 2080 21002.0\n", "1.5\n", "1.0\n", "0.5\n", "0\n", "Likely range of modeled responses to stylized pathways\n", " Faster CO/two.dnom reductions (blue in b & c) result in a higher \n", "probability of limiting warming to 1.5°C \n", " No reduction of net non-CO/two.dnom radiative forcing (purple in d) \n", "results in a lower probability of limiting warming to 1.5°C Global CO/two.dnom emissions reach net zero in 2055 while net \n", "non-CO/two.dnom radiative forcing is reduced a/f_ter 2030 (grey in b, c & d)\n", "Figure SPM.1 | Panel a: Observed monthly global mean surface temperature (GMST, grey line up to 2017, from the HadCRUT4, GISTEMP , Cowtan–Way, and \n", "NOAA datasets) change and estimated anthropogenic global warming (solid orange line up to 2017, with orange shading indicating assessed likely range). Orange \n", "dashed arrow and horizontal orange error bar show respectively the central estimate and likely range of the time at which 1.5°C is reached if the current rate \n", "of warming continues. The grey plume on the right of panel a shows the likely range of warming responses, computed with a simple climate model, to a stylized \n", "pathway (hypothetical future) in which net CO2 emissions (grey line in panels b and c) decline in a straight line from 2020 to reach net zero in 2055 and net non-\n", "CO2 radiative forcing (grey line in panel d) increases to 2030 and then declines. The blue plume in panel a) shows the response to faster CO2 emissions reductions \n", "(blue line in panel b), reaching net zero in 2040, reducing cumulative CO2 emissions (panel c). The purple plume shows the response to net CO2 emissions declining \n", "to zero in 2055, with net non-CO2 forcing remaining constant after 2030. The vertical error bars on right of panel a) show the likely ranges (thin lines) and central \n", "terciles (33rd – 66th percentiles, thick lines) of the estimated distribution of warming in 2100 under these three stylized pathways. Vertical dotted error bars in \n", "panels b, c and d show the likely range of historical annual and cumulative global net CO2 emissions in 2017 (data from the Global Carbon Project) and of net \n", "non-CO2 radiative forcing in 2011 from AR5, respectively. Vertical axes in panels c and d are scaled to represent approximately equal effects on GMST. {1.2.1, 1.2.3, \n", "1.2.4, 2.3, Figure 1.2 and Chapter 1 Supplementary Material, Cross-Chapter Box 2 in Chapter 1}\n", "SPM Summary for Policymakers7B. Projected Climate Change, Potential Impacts and Associated Risks\n", "B.1 Climate models project robust7 differences in regional climate characteristics between present-day \n", "and global warming of 1.5°C,8 and between 1.5°C and 2°C.8 These differences include increases \n", "in: mean temperature in most land and ocean regions (high confidence), hot extremes in most \n", "inhabited regions (high confidence), heavy precipitation in several regions (medium confidence), \n", "and the probability of drought and precipitation deficits in some regions (medium confidence). \n", "{3.3}\n", "B.1.1 Evidence from attributed changes in some climate and weather extremes for a global warming of about 0.5°C supports \n", "the assessment that an additional 0.5°C of warming compared to present is associated with further detectable changes in \n", "these extremes (medium confidence). Several regional changes in climate are assessed to occur with global warming up \n", "to 1.5°C compared to pre-industrial levels, including warming of extreme temperatures in many regions (high confidence), \n", "increases in frequency, intensity, and/or amount of heavy precipitation in several regions (high confidence), and an increase \n", "in intensity or frequency of droughts in some regions (medium confidence). {3.2, 3.3.1, 3.3.2, 3.3.3, 3.3.4, Table 3.2}\n", "B.1.2 Temperature extremes on land are projected to warm more than GMST (high confidence): extreme hot days in mid-latitudes \n", "warm by up to about 3°C at global warming of 1.5°C and about 4°C at 2°C, and extreme cold nights in high latitudes warm \n", "by up to about 4.5°C at 1.5°C and about 6°C at 2°C (high confidence). The number of hot days is projected to increase in \n", "most land regions, with highest increases in the tropics (high confidence). {3.3.1, 3.3.2, Cross-Chapter Box 8 in Chapter 3}\n", "B.1.3 Risks from droughts and precipitation deficits are projected to be higher at 2°C compared to 1.5°C of global warming in \n", "some regions (medium confidence). Risks from heavy precipitation events are projected to be higher at 2°C compared to \n", "1.5°C of global warming in several northern hemisphere high-latitude and/or high-elevation regions, eastern Asia and \n", "eastern North America (medium confidence). Heavy precipitation associated with tropical cyclones is projected to be \n", "higher at 2°C compared to 1.5°C global warming (medium confidence). There is generally low confidence in projected \n", "changes in heavy precipitation at 2°C compared to 1.5°C in other regions. Heavy precipitation when aggregated at global \n", "scale is projected to be higher at 2°C than at 1.5°C of global warming (medium confidence). As a consequence of heavy \n", "precipitation, the fraction of the global land area affected by flood hazards is projected to be larger at 2°C compared to \n", "1.5°C of global warming (medium confidence). {3.3.1, 3.3.3, 3.3.4, 3.3.5, 3.3.6}\n", "B.2 By 2100, global mean sea level rise is projected to be around 0.1 metre lower with global warming \n", "of 1.5°C compared to 2°C (medium confidence). Sea level will continue to rise well beyond 2100 \n", "(high confidence), and the magnitude and rate of this rise depend on future emission pathways. \n", "A slower rate of sea level rise enables greater opportunities for adaptation in the human and \n", "ecological systems of small islands, low-lying coastal areas and deltas (medium confidence). \n", "{3.3, 3.4, 3.6}\n", "B.2.1 Model-based projections of global mean sea level rise (relative to 1986–2005) suggest an indicative range of 0.26 to 0.77 \n", "m by 2100 for 1.5°C of global warming, 0.1 m (0.04–0.16 m) less than for a global warming of 2°C (medium confidence). \n", "A reduction of 0.1 m in global sea level rise implies that up to 10 million fewer people would be exposed to related risks, \n", "based on population in the year 2010 and assuming no adaptation (medium confidence). {3.4.4, 3.4.5, 4.3.2}\n", "B.2.2 Sea level rise will continue beyond 2100 even if global warming is limited to 1.5°C in the 21st century (high confidence). \n", "Marine ice sheet instability in Antarctica and/or irreversible loss of the Greenland ice sheet could result in multi-metre rise \n", "in sea level over hundreds to thousands of years. These instabilities could be triggered at around 1.5°C to 2°C of global \n", "warming (medium confidence). (Figure SPM.2) {3.3.9, 3.4.5, 3.5.2, 3.6.3, Box 3.3}\n", "7 Robust is here used to mean that at least two thirds of climate models show the same sign of changes at the grid point scale, and that differences in large regions are statistically \n", " significant.\n", "8 Projected changes in impacts between different levels of global warming are determined with respect to changes in global mean surface air temperature.\n", "SPMSummary for Policymakers8B.2.3 Increasing warming amplifies the exposure of small islands, low-lying coastal areas and deltas to the risks associated with \n", "sea level rise for many human and ecological systems, including increased saltwater intrusion, flooding and damage to \n", "infrastructure (high confidence). Risks associated with sea level rise are higher at 2°C compared to 1.5°C. The slower rate \n", "of sea level rise at global warming of 1.5°C reduces these risks, enabling greater opportunities for adaptation including \n", "managing and restoring natural coastal ecosystems and infrastructure reinforcement (medium confidence). (Figure SPM.2) \n", "{3.4.5, Box 3.5}\n", "B.3 On land, impacts on biodiversity and ecosystems, including species loss and extinction, are \n", "projected to be lower at 1.5°C of global warming compared to 2°C. Limiting global warming to \n", "1.5°C compared to 2°C is projected to lower the impacts on terrestrial, freshwater and coastal \n", "ecosystems and to retain more of their services to humans (high confidence). (Figure SPM.2) \n", "{3.4, 3.5, Box 3.4, Box 4.2, Cross-Chapter Box 8 in Chapter 3} \n", "B.3.1 Of 105,000 species studied,9 6% of insects, 8% of plants and 4% of vertebrates are projected to lose over half of their \n", "climatically determined geographic range for global warming of 1.5°C, compared with 18% of insects, 16% of plants and \n", "8% of vertebrates for global warming of 2°C (medium confidence). Impacts associated with other biodiversity-related \n", "risks such as forest fires and the spread of invasive species are lower at 1.5°C compared to 2°C of global warming (high \n", "confidence). {3.4.3, 3.5.2}\n", "B.3.2 Approximately 4% (interquartile range 2–7%) of the global terrestrial land area is projected to undergo a transformation \n", "of ecosystems from one type to another at 1°C of global warming, compared with 13% (interquartile range 8–20%) at 2°C \n", "(medium confidence). This indicates that the area at risk is projected to be approximately 50% lower at 1.5°C compared to \n", "2°C (medium confidence). {3.4.3.1, 3.4.3.5}\n", "B.3.3 High-latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss, with woody \n", "shrubs already encroaching into the tundra (high confidence) and this will proceed with further warming. Limiting global \n", "warming to 1.5°C rather than 2°C is projected to prevent the thawing over centuries of a permafrost area in the range of \n", "1.5 to 2.5 million km2 (medium confidence). {3.3.2, 3.4.3, 3.5.5} \n", "B.4 Limiting global warming to 1.5°C compared to 2°C is projected to reduce increases in ocean \n", "temperature as well as associated increases in ocean acidity and decreases in ocean oxygen levels \n", "(high confidence). Consequently, limiting global warming to 1.5°C is projected to reduce risks \n", "to marine biodiversity, fisheries, and ecosystems, and their functions and services to humans, \n", "as illustrated by recent changes to Arctic sea ice and warm-water coral reef ecosystems (high \n", "confidence). {3.3, 3.4, 3.5, Box 3.4, Box 3.5}\n", "B.4.1 There is high confidence that the probability of a sea ice-free Arctic Ocean during summer is substantially lower at global \n", "warming of 1.5°C when compared to 2°C. With 1.5°C of global warming, one sea ice-free Arctic summer is projected per \n", "century. This likelihood is increased to at least one per decade with 2°C global warming. Effects of a temperature overshoot \n", "are reversible for Arctic sea ice cover on decadal time scales (high confidence). {3.3.8, 3.4.4.7}\n", "B.4.2 Global warming of 1.5°C is projected to shift the ranges of many marine species to higher latitudes as well as increase the \n", "amount of damage to many ecosystems. It is also expected to drive the loss of coastal resources and reduce the productivity of \n", "fisheries and aquaculture (especially at low latitudes). The risks of climate-induced impacts are projected to be higher at 2°C \n", "than those at global warming of 1.5°C (high confidence). Coral reefs, for example, are projected to decline by a further 70–90% \n", "at 1.5°C (high confidence) with larger losses (>99%) at 2°C (very high confidence). The risk of irreversible loss of many marine \n", "and coastal ecosystems increases with global warming, especially at 2°C or more (high confidence). {3.4.4, Box 3.4}\n", "9 Consistent with earlier studies, illustrative numbers were adopted from one recent meta-study.\n", "SPM Summary for Policymakers910 Here, impacts on economic growth refer to changes in gross domestic product (GDP). Many impacts, such as loss of human lives, cultural heritage and ecosystem services, are difficult \n", "to value and monetize.B.4.3 The level of ocean acidification due to increasing CO2 concentrations associated with global warming of 1.5°C is projected to \n", "amplify the adverse effects of warming, and even further at 2°C, impacting the growth, development, calcification, survival, \n", "and thus abundance of a broad range of species, for example, from algae to fish (high confidence). {3.3.10, 3.4.4}\n", "B.4.4 Impacts of climate change in the ocean are increasing risks to fisheries and aquaculture via impacts on the physiology, \n", "survivorship, habitat, reproduction, disease incidence, and risk of invasive species (medium confidence) but are projected to \n", "be less at 1.5°C of global warming than at 2°C. One global fishery model, for example, projected a decrease in global annual \n", "catch for marine fisheries of about 1.5 million tonnes for 1.5°C of global warming compared to a loss of more than 3 million \n", "tonnes for 2°C of global warming (medium confidence). {3.4.4, Box 3.4}\n", "B.5 Climate-related risks to health, livelihoods, food security, water supply, human security, and \n", "economic growth are projected to increase with global warming of 1.5°C and increase further with \n", "2°C. (Figure SPM.2) {3.4, 3.5, 5.2, Box 3.2, Box 3.3, Box 3.5, Box 3.6, Cross-Chapter Box 6 in Chapter \n", "3, Cross-Chapter Box 9 in Chapter 4, Cross-Chapter Box 12 in Chapter 5, 5.2} \n", "B.5.1 Populations at disproportionately higher risk of adverse consequences with global warming of 1.5°C and beyond include \n", "disadvantaged and vulnerable populations, some indigenous peoples, and local communities dependent on agricultural or \n", "coastal livelihoods (high confidence). Regions at disproportionately higher risk include Arctic ecosystems, dryland regions, \n", "small island developing states, and Least Developed Countries (high confidence). Poverty and disadvantage are expected \n", "to increase in some populations as global warming increases; limiting global warming to 1.5°C, compared with 2°C, could \n", "reduce the number of people both exposed to climate-related risks and susceptible to poverty by up to several hundred \n", "million by 2050 (medium confidence). {3.4.10, 3.4.11, Box 3.5, Cross-Chapter Box 6 in Chapter 3, Cross-Chapter Box 9 in \n", "Chapter 4, Cross-Chapter Box 12 in Chapter 5, 4.2.2.2, 5.2.1, 5.2.2, 5.2.3, 5.6.3}\n", "B.5.2 Any increase in global warming is projected to affect human health, with primarily negative consequences (high confidence). \n", "Lower risks are projected at 1.5°C than at 2°C for heat-related morbidity and mortality (very high confidence) and for \n", "ozone-related mortality if emissions needed for ozone formation remain high (high confidence). Urban heat islands often \n", "amplify the impacts of heatwaves in cities (high confidence). Risks from some vector-borne diseases, such as malaria and \n", "dengue fever, are projected to increase with warming from 1.5°C to 2°C, including potential shifts in their geographic range \n", "(high confidence). {3.4.7, 3.4.8, 3.5.5.8}\n", "B.5.3 Limiting warming to 1.5°C compared with 2°C is projected to result in smaller net reductions in yields of maize, rice, wheat, \n", "and potentially other cereal crops, particularly in sub-Saharan Africa, Southeast Asia, and Central and South America, and \n", "in the CO2-dependent nutritional quality of rice and wheat (high confidence). Reductions in projected food availability are \n", "larger at 2°C than at 1.5°C of global warming in the Sahel, southern Africa, the Mediterranean, central Europe, and the \n", "Amazon (medium confidence). Livestock are projected to be adversely affected with rising temperatures, depending on the \n", "extent of changes in feed quality, spread of diseases, and water resource availability (high confidence). {3.4.6, 3.5.4, 3.5.5, \n", "Box 3.1, Cross-Chapter Box 6 in Chapter 3, Cross-Chapter Box 9 in Chapter 4}\n", "B.5.4 Depending on future socio-economic conditions, limiting global warming to 1.5°C compared to 2°C may reduce the \n", "proportion of the world population exposed to a climate change-induced increase in water stress by up to 50%, although \n", "there is considerable variability between regions (medium confidence). Many small island developing states could \n", "experience lower water stress as a result of projected changes in aridity when global warming is limited to 1.5°C, as \n", "compared to 2°C (medium confidence). {3.3.5, 3.4.2, 3.4.8, 3.5.5, Box 3.2, Box 3.5, Cross-Chapter Box 9 in Chapter 4}\n", "B.5.5 Risks to global aggregated economic growth due to climate change impacts are projected to be lower at 1.5°C than at \n", "2°C by the end of this century10 (medium confidence). This excludes the costs of mitigation, adaptation investments and \n", "the benefits of adaptation. Countries in the tropics and Southern Hemisphere subtropics are projected to experience the \n", "largest impacts on economic growth due to climate change should global warming increase from 1.5°C to 2°C (medium \n", "confidence). {3.5.2, 3.5.3} \n", "SPMSummary for Policymakers10B.5.6 Exposure to multiple and compound climate-related risks increases between 1.5°C and 2°C of global warming, with greater \n", "proportions of people both so exposed and susceptible to poverty in Africa and Asia (high confidence). For global warming \n", "from 1.5°C to 2°C, risks across energy, food, and water sectors could overlap spatially and temporally, creating new and \n", "exacerbating current hazards, exposures, and vulnerabilities that could affect increasing numbers of people and regions \n", "(medium confidence). {Box 3.5, 3.3.1, 3.4.5.3, 3.4.5.6, 3.4.11, 3.5.4.9}\n", "B.5.7 There are multiple lines of evidence that since AR5 the assessed levels of risk increased for four of the five Reasons for \n", "Concern (RFCs) for global warming to 2°C (high confidence). The risk transitions by degrees of global warming are now: \n", "from high to very high risk between 1.5°C and 2°C for RFC1 (Unique and threatened systems) (high confidence); from \n", "moderate to high risk between 1°C and 1.5°C for RFC2 (Extreme weather events) (medium confidence); from moderate to \n", "high risk between 1.5°C and 2°C for RFC3 (Distribution of impacts) (high confidence); from moderate to high risk between \n", "1.5°C and 2.5°C for RFC4 (Global aggregate impacts) (medium confidence); and from moderate to high risk between 1°C \n", "and 2.5°C for RFC5 (Large-scale singular events) (medium confidence). (Figure SPM.2) {3.4.13; 3.5, 3.5.2}\n", "B.6 Most adaptation needs will be lower for global warming of 1.5°C compared to 2°C (high confidence). \n", "There are a wide range of adaptation options that can reduce the risks of climate change (high \n", "confidence). There are limits to adaptation and adaptive capacity for some human and natural \n", "systems at global warming of 1.5°C, with associated losses (medium confidence). The number and \n", "availability of adaptation options vary by sector (medium confidence). {Table 3.5, 4.3, 4.5, Cross-\n", "Chapter Box 9 in Chapter 4, Cross-Chapter Box 12 in Chapter 5} \n", "B.6.1 A wide range of adaptation options are available to reduce the risks to natural and managed ecosystems (e.g., ecosystem-\n", "based adaptation, ecosystem restoration and avoided degradation and deforestation, biodiversity management, \n", "sustainable aquaculture, and local knowledge and indigenous knowledge), the risks of sea level rise (e.g., coastal defence \n", "and hardening), and the risks to health, livelihoods, food, water, and economic growth, especially in rural landscapes \n", "(e.g., efficient irrigation, social safety nets, disaster risk management, risk spreading and sharing, and community-\n", "based adaptation) and urban areas (e.g., green infrastructure, sustainable land use and planning, and sustainable water \n", "management) (medium confidence). {4.3.1, 4.3.2, 4.3.3, 4.3.5, 4.5.3, 4.5.4, 5.3.2, Box 4.2, Box 4.3, Box 4.6, Cross-Chapter \n", "Box 9 in Chapter 4}.\n", "B.6.2 Adaptation is expected to be more challenging for ecosystems, food and health systems at 2°C of global warming than for \n", "1.5°C (medium confidence). Some vulnerable regions, including small islands and Least Developed Countries, are projected \n", "to experience high multiple interrelated climate risks even at global warming of 1.5°C (high confidence). {3.3.1, 3.4.5, \n", "Box 3.5, Table 3.5, Cross-Chapter Box 9 in Chapter 4, 5.6, Cross-Chapter Box 12 in Chapter 5, Box 5.3}\n", "B.6.3 Limits to adaptive capacity exist at 1.5°C of global warming, become more pronounced at higher levels of warming and \n", "vary by sector, with site-specific implications for vulnerable regions, ecosystems and human health (medium confidence). \n", "{Cross-Chapter Box 12 in Chapter 5, Box 3.5, Table 3.5} \n", "SPM Summary for Policymakers1110 Here, impacts on economic growth refer to changes in gross domestic product (GDP). Many impacts, such as loss of human lives, cultural heritage and ecosystem services, are difficult \n", " to value and monetize.1.01.52.0\n", "01.01.52.00Global mean surface temperature change \n", "relative to pre-industrial levels (/zero.numrC)Global mean surface temperature change \n", "relative to pre-industrial levels (/zero.numrC)2006-2015How the level of global warming affects impacts and/or risks associated with \n", "the Reasons for Concern (RFCs) and selected natural, managed and human \n", "systems\n", "Impacts and risks associated with the Reasons for Concern (RFCs)Purple indicates very high \n", "risks of severe impacts/risks \n", "and the presence of \n", "significant irreversibility or \n", "the persistence of \n", "climate-related hazards, \n", "combined with limited \n", "ability to adapt due to the \n", "nature of the hazard or \n", "impacts/risks. \n", "Red indicates severe and \n", "widespread impacts/risks. \n", "Yellow indicates that \n", "impacts/risks are detectable \n", "and attributable to climate \n", "change with at least medium \n", "confidence. \n", "White indicates that no \n", "impacts are detectable and \n", "attributable to climate \n", "change.Five Reasons For Concern (RFCs) illustrate the impacts and risks of \n", "different levels of global warming for people, economies and ecosystems \n", "across sectors and regions.\n", "Heat-related \n", "morbidity \n", "and mortalityLevel of additional \n", "impact/risk due \n", "to climate changeRFC1\n", "Unique and \n", "threatened \n", "systemsRFC2\n", "Extreme \n", "weather \n", "events RFC4\n", "Global \n", "aggregate \n", "impactsRFC5\n", "Large scale \n", "singular \n", "eventsRFC3\n", "Distribution \n", "of impacts\n", "Warm-water\n", "coralsTerrestrial\n", "ecosystemsTourism2006-2015\n", "HVHVHHHH\n", "HM\n", "M-HH\n", "MM\n", "MM\n", "M\n", "HMH\n", "HH\n", "MHH\n", "MM\n", "HM\n", "HM\n", "HM\n", "HMHImpacts and risks for selected natural, managed and human systems\n", "Confidence level for transition: L=Low, M=Medium, H=High and VH=Very highMangroves Small-scale\n", "low-latitude\n", "fisheriesArctic\n", "regionCoastal \n", "floodingFluvial \n", "floodingCrop \n", "yieldsUndetectableModerateHighVery high\n", "Figure SPM.2 | Five integrative reasons for concern (RFCs) provide a framework for summarizing key impacts and risks across sectors and regions, and were \n", "introduced in the IPCC Third Assessment Report. RFCs illustrate the implications of global warming for people, economies and ecosystems. Impacts and/or risks \n", "for each RFC are based on assessment of the new literature that has appeared. As in AR5, this literature was used to make expert judgments to assess the levels \n", "of global warming at which levels of impact and/or risk are undetectable, moderate, high or very high. The selection of impacts and risks to natural, managed and \n", "human systems in the lower panel is illustrative and is not intended to be fully comprehensive. {3.4, 3.5, 3.5.2.1, 3.5.2.2, 3.5.2.3, 3.5.2.4, 3.5.2.5, 5.4.1, 5.5.3, \n", "5.6.1, Box 3.4}\n", "RFC1 Unique and threatened systems: ecological and human systems that have restricted geographic ranges constrained by climate-related conditions and \n", "have high endemism or other distinctive properties. Examples include coral reefs, the Arctic and its indigenous people, mountain glaciers and biodiversity hotspots. \n", "RFC2 Extreme weather events: risks/impacts to human health, livelihoods, assets and ecosystems from extreme weather events such as heat waves, heavy rain, \n", "drought and associated wildfires, and coastal flooding. \n", "RFC3 Distribution of impacts: risks/impacts that disproportionately affect particular groups due to uneven distribution of physical climate change hazards, \n", "exposure or vulnerability. \n", "RFC4 Global aggregate impacts: global monetary damage, global-scale degradation and loss of ecosystems and biodiversity. \n", "RFC5 Large-scale singular events: are relatively large, abrupt and sometimes irreversible changes in systems that are caused by global warming. Examples \n", "include disintegration of the Greenland and Antarctic ice sheets.\n", "SPMSummary for Policymakers1211 References to pathways limiting global warming to 2°C are based on a 66% probability of staying below 2°C.\n", "12 Non-CO2 emissions included in this Report are all anthropogenic emissions other than CO2 that result in radiative forcing. These include short-lived climate forcers, such as methane, \n", " some fluorinated gases, ozone precursors, aerosols or aerosol precursors, such as black carbon and sulphur dioxide, respectively, as well as long-lived greenhouse gases, such as nitrous \n", " oxide or some fluorinated gases. The radiative forcing associated with non-CO2 emissions and changes in surface albedo is referred to as non-CO2 radiative forcing. {2.2.1}\n", "13 There is a clear scientific basis for a total carbon budget consistent with limiting global warming to 1.5°C. However, neither this total carbon budget nor the fraction of this budget \n", " taken up by past emissions were assessed in this Report.\n", "14 Irrespective of the measure of global temperature used, updated understanding and further advances in methods have led to an increase in the estimated remaining carbon budget of \n", " about 300 GtCO2 compared to AR5. (medium confidence) {2.2.2}\n", "15 These estimates use observed GMST to 2006–2015 and estimate future temperature changes using near surface air temperatures. C. Emission Pathways and System Transitions Consistent with 1.5°C \n", "Global Warming\n", "C.1 In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions \n", "decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero \n", "around 2050 (2045–2055 interquartile range). For limiting global warming to below 2°C11 CO2 \n", "emissions are projected to decline by about 25% by 2030 in most pathways (10–30% interquartile \n", "range) and reach net zero around 2070 (2065–2080 interquartile range). Non-CO2 emissions in \n", "pathways that limit global warming to 1.5°C show deep reductions that are similar to those in \n", "pathways limiting warming to 2°C. (high confidence) (Figure SPM.3a) {2.1, 2.3, Table 2.4} \n", "C.1.1 CO2 emissions reductions that limit global warming to 1.5°C with no or limited overshoot can involve different portfolios of \n", "mitigation measures, striking different balances between lowering energy and resource intensity, rate of decarbonization, \n", "and the reliance on carbon dioxide removal. Different portfolios face different implementation challenges and potential \n", "synergies and trade-offs with sustainable development. (high confidence) (Figure SPM.3b) {2.3.2, 2.3.4, 2.4, 2.5.3} \n", "C.1.2 Modelled pathways that limit global warming to 1.5°C with no or limited overshoot involve deep reductions in emissions \n", "of methane and black carbon (35% or more of both by 2050 relative to 2010). These pathways also reduce most of the \n", "cooling aerosols, which partially offsets mitigation effects for two to three decades. Non-CO2 emissions12 can be reduced \n", "as a result of broad mitigation measures in the energy sector. In addition, targeted non-CO2 mitigation measures can \n", "reduce nitrous oxide and methane from agriculture, methane from the waste sector, some sources of black carbon, and \n", "hydrofluorocarbons. High bioenergy demand can increase emissions of nitrous oxide in some 1.5°C pathways, highlighting \n", "the importance of appropriate management approaches. Improved air quality resulting from projected reductions in many \n", "non-CO2 emissions provide direct and immediate population health benefits in all 1.5°C model pathways. (high confidence) \n", "(Figure SPM.3a) {2.2.1, 2.3.3, 2.4.4, 2.5.3, 4.3.6, 5.4.2} \n", "C.1.3 Limiting global warming requires limiting the total cumulative global anthropogenic emissions of CO2 since the pre-\n", "industrial period, that is, staying within a total carbon budget (high confidence).13 By the end of 2017, anthropogenic CO2 \n", "emissions since the pre-industrial period are estimated to have reduced the total carbon budget for 1.5°C by approximately \n", "2200 ± 320 GtCO2 (medium confidence). The associated remaining budget is being depleted by current emissions of \n", "42 ± 3 GtCO2 per year (high confidence). The choice of the measure of global temperature affects the estimated remaining \n", "carbon budget. Using global mean surface air temperature, as in AR5, gives an estimate of the remaining carbon budget of \n", "580 GtCO2 for a 50% probability of limiting warming to 1.5°C, and 420 GtCO2 for a 66% probability (medium confidence).14 \n", "Alternatively, using GMST gives estimates of 770 and 570 GtCO2, for 50% and 66% probabilities,15 respectively (medium \n", "confidence). Uncertainties in the size of these estimated remaining carbon budgets are substantial and depend on several \n", "factors. Uncertainties in the climate response to CO2 and non-CO2 emissions contribute ±400 GtCO2 and the level of historic \n", "warming contributes ±250 GtCO2 (medium confidence). Potential additional carbon release from future permafrost thawing \n", "and methane release from wetlands would reduce budgets by up to 100 GtCO2 over the course of this century and more \n", "thereafter (medium confidence). In addition, the level of non-CO2 mitigation in the future could alter the remaining carbon \n", "budget by 250 GtCO2 in either direction (medium confidence). {1.2.4, 2.2.2, 2.6.1, Table 2.2, Chapter 2 Supplementary \n", "Material}\n", "C.1.4 Solar radiation modification (SRM) measures are not included in any of the available assessed pathways. Although some \n", "SRM measures may be theoretically effective in reducing an overshoot, they face large uncertainties and knowledge gaps \n", "SPM Summary for Policymakers13as well as substantial risks and institutional and social constraints to deployment related to governance, ethics, and impacts \n", "on sustainable development. They also do not mitigate ocean acidification. (medium confidence) {4.3.8, Cross-Chapter \n", "Box 10 in Chapter 4}\n", "2010 2020 2030 2040 2050 2060 2070 2080 2090 2100\n", "-20-1001020304050\n", "Black carbon emissions\n", "Nitrous oxide emissionsMethane emissionsEmissions of non-CO/two.dnom forcers are also reduced \n", "or limited in pathways limiting global warming \n", "to 1.5°C with no or limited overshoot, but \n", "they do not reach zero globally. Non-CO/two.subs emissions relative to 2010\n", "Billion tonnes of CO/two.subs/yrGlobal emissions pathway characteristics\n", "General characteristics of the evolution of anthropogenic net emissions of CO/two.dnom, and total emissions of \n", "methane, black carbon, and nitrous oxide in model pathways that limit global warming to 1.5°C with no or \n", "limited overshoot. Net emissions are defined as anthropogenic emissions reduced by anthropogenic \n", "removals. Reductions in net emissions can be achieved through different portfolios of mitigation measures \n", "illustrated in Figure SPM.3b.\n", "Global total net CO/two.dnom emissions\n", "2020 2040 2060 2080 2100\n", "01\n", "2020 2040 2060 2080 2100\n", "01\n", "2020 2040 2060 2080 2100\n", "01\n", "Four illustrative model pathways\n", "In pathways limiting global warming to 1.5°C \n", "with no or limited overshoot as well as in \n", "pathways with a higher overshoot, CO/two.tnum emissions \n", "are reduced to net zero globally around 2050.\n", "P1\n", "P2\n", "P3\n", "P4\n", "Pathways with higher overshoot\n", "Pathways limiting global warming below 2°C\n", "(Not shown above) Pathways limiting global warming to 1.5°C with no or limited overshoot Timing of net zero CO/two.dnom\n", "Line widths depict the 5-95th \n", "percentile and the 25-75th \n", "percentile of scenarios\n", "Figure SPM.3a | Global emissions pathway characteristics. The main panel shows global net anthropogenic CO2 emissions in pathways limiting global warming \n", "to 1.5°C with no or limited (less than 0.1°C) overshoot and pathways with higher overshoot. The shaded area shows the full range for pathways analysed in this \n", "Report. The panels on the right show non-CO2 emissions ranges for three compounds with large historical forcing and a substantial portion of emissions coming \n", "from sources distinct from those central to CO2 mitigation. Shaded areas in these panels show the 5–95% (light shading) and interquartile (dark shading) ranges \n", "of pathways limiting global warming to 1.5°C with no or limited overshoot. Box and whiskers at the bottom of the figure show the timing of pathways reaching \n", "global net zero CO2 emission levels, and a comparison with pathways limiting global warming to 2°C with at least 66% probability. Four illustrative model pathways \n", "are highlighted in the main panel and are labelled P1, P2, P3 and P4, corresponding to the LED, S1, S2, and S5 pathways assessed in Chapter 2. Descriptions and \n", "characteristics of these pathways are available in Figure SPM.3b. {2.1, 2.2, 2.3, Figure 2.5, Figure 2.10, Figure 2.11}\n", "SPMSummary for Policymakers14Breakdown of contributions to global net CO/two.dnom emissions in four illustrative model pathways \n", "P1: A scenario in which social, \n", "business and technological innovations \n", "result in lower energy demand up to \n", "2050 while living standards rise, \n", "especially in the global South. A \n", "downsized energy system enables \n", "rapid decarbonization of energy supply. \n", "Afforestation is the only CDR option \n", "considered; neither fossil fuels with CCS \n", "nor BECCS are used.P2: A scenario with a broad focus on \n", "sustainability including energy \n", "intensity, human development, \n", "economic convergence and \n", "international cooperation, as well as \n", "shi/f_ts towards sustainable and healthy \n", "consumption patterns, low-carbon \n", "technology innovation, and \n", "well-managed land systems with \n", "limited societal acceptability for BECCS.P3: A middle-of-the-road scenario in\n", "which societal as well as technological \n", "development follows historical \n", "patterns. Emissions reductions are \n", "mainly achieved by changing the way in \n", "which energy and products are \n", "produced, and to a lesser degree by \n", "reductions in demand.P4: A resource- and energy-intensive \n", "scenario in which economic growth and \n", "globalization lead to widespread \n", "adoption of greenhouse-gas-intensive \n", "lifestyles, including high demand for \n", "transportation fuels and livestock \n", "products. Emissions reductions are \n", "mainly achieved through technological \n", "means, making strong use of CDR \n", "through the deployment of BECCS.\n", "Fossil fuel and industry AFOLU BECCS\n", "-2002040\n", "2020 2060 2100-2002040\n", "2020 2060 2100-2002040\n", "2020 2060 2100-2002040\n", "2020 2060 2100\n", "No or limited overshoot\n", "-58\n", "-93\n", "-50\n", "-82\n", "-15\n", "-32\n", "60\n", "77\n", "-78\n", "-97\n", "-37\n", "-87\n", "-25\n", "-74\n", "59\n", "150\n", "-11\n", "-16\n", "430\n", "833\n", "0\n", "0\n", "0.2\n", "-24\n", "-33\n", "5\n", "6Pathway classification\n", "CO/two.dnom emission change in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", "Kyoto-GHG emissions * in 2030 (% rel to 2010) \n", " in 2050 (% rel to 2010) \n", "Final energy demand** in 2030 (% rel to 2010) \n", " in 2050 (% rel to 2010)\n", "Renewable share in electricity in 2030 (%)\n", " in 2050 (%)\n", "Primary energy from coal in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", " from oil in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", " from gas in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", " from nuclear in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", " from biomass in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010) \n", " from non-biomass renewables in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", "Cumulative CCS until 2100 (GtCO/two.dnom)\n", " of which BECCS (GtCO/two.dnom)\n", "Land area of bioenergy crops in 2050 (million km/two.numr)\n", "Agricultural CH/four.dnom emissions in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", "Agricultural N/two.dnomO emissions in 2030 (% rel to 2010)\n", " in 2050 (% rel to 2010)\n", " No or limited overshoot\n", "-47\n", "-95\n", "-49\n", "-89\n", "-5\n", "2\n", "58\n", "81\n", "-61\n", "-77\n", "-13\n", "-50\n", "-20\n", "-53\n", "83\n", "98\n", "0\n", "49\n", "470\n", "1327\n", "348\n", "151\n", "0.9\n", "-48\n", "-69\n", "-26\n", "-26No or limited overshoot\n", "-41\n", "-91\n", "-35\n", "-78\n", "17\n", "21\n", "48\n", "63\n", "-75\n", "-73\n", "-3\n", "-81\n", "33\n", "21\n", "98\n", "501\n", "36\n", "121\n", "315\n", "878\n", "687\n", "414\n", "2.8\n", "1\n", "-23\n", "15\n", "0Higher overshoot\n", "4\n", "-97\n", "-2\n", "-80\n", "39\n", "44\n", "25\n", "70\n", "-59\n", "-97\n", "86\n", "-32\n", "37\n", "-48\n", "106\n", "468\n", "-1\n", "418\n", "110\n", "1137\n", "1218\n", "1191\n", "7.2\n", "14\n", "2\n", "3\n", "39No or limited overshoot\n", "(-58,-40)\n", "(-107,-94)\n", "(-51,-39)\n", "(-93,-81)\n", "(-12,7)\n", "(-11,22)\n", "(47,65)\n", "(69,86)\n", "(-78, -59) \n", "(-95, -74)\n", "(-34,3)\n", "(-78,-31)\n", "(-26,21)\n", "(-56,6)\n", "(44,102)\n", "(91,190)\n", "(29,80)\n", "(123,261)\n", "(245,436)\n", "(576,1299)\n", "(550,1017)\n", "(364,662)\n", "(1.5,3.2)\n", "(-30,-11)\n", "(-47,-24)\n", "(-21,3)\n", "(-26,1)Characteristics of four illustrative model pathways\n", "Different mitigation strategies can achieve the net emissions reductions that would be required to follow a \n", "pathway that limits global warming to 1.5°C with no or limited overshoot. All pathways use Carbon Dioxide \n", "Removal (CDR), but the amount varies across pathways, as do the relative contributions of Bioenergy with \n", "Carbon Capture and Storage (BECCS) and removals in the Agriculture, Forestry and Other Land Use (AFOLU) \n", "sector. This has implications for emissions and several other pathway characteristics.\n", "P1 P2 P3 P4\n", "P1 P2 P3 P4 Interquartile rangeBillion tonnes CO/two.subs per year (GtCO/two.dnom/yr)\n", "Global indicatorsBillion tonnes CO/two.subs per year (GtCO/two.dnom/yr) Billion tonnes CO/two.subs per year (GtCO/two.dnom/yr) Billion tonnes CO/two.subs per year (GtCO/two.dnom/yr)\n", "NOTE: Indicators have been selected to show global trends identified by the Chapter 2 assessment. \n", "National and sectoral characteristics can differ substantially from the global trends shown above.* Kyoto-gas emissions are based on IPCC Second Assessment Report GWP-100\n", "** Changes in energy demand are associated with improvements in energy \n", "efficiency and behaviour change\n", "SPM Summary for Policymakers15Figure SPM.3b | Characteristics of four illustrative model pathways in relation to global warming of 1.5°C introduced in Figure SPM.3a. These pathways were \n", "selected to show a range of potential mitigation approaches and vary widely in their projected energy and land use, as well as their assumptions about future \n", "socio-economic developments, including economic and population growth, equity and sustainability. A breakdown of the global net anthropogenic CO2 emissions \n", "into the contributions in terms of CO2 emissions from fossil fuel and industry; agriculture, forestry and other land use (AFOLU); and bioenergy with carbon capture \n", "and storage (BECCS) is shown. AFOLU estimates reported here are not necessarily comparable with countries’ estimates. Further characteristics for each of these \n", "pathways are listed below each pathway. These pathways illustrate relative global differences in mitigation strategies, but do not represent central estimates, \n", "national strategies, and do not indicate requirements. For comparison, the right-most column shows the interquartile ranges across pathways with no or limited \n", "overshoot of 1.5°C. Pathways P1, P2, P3 and P4 correspond to the LED, S1, S2 and S5 pathways assessed in Chapter 2 (Figure SPM.3a). {2.2.1, 2.3.1, 2.3.2, \n", "2.3.3, 2.3.4, 2.4.1, 2.4.2, 2.4.4, 2.5.3, Figure 2.5, Figure 2.6, Figure 2.9, Figure 2.10, Figure 2.11, Figure 2.14, Figure 2.15, Figure 2.16, Figure 2.17, Figure 2.24, \n", "Figure 2.25, Table 2.4, Table 2.6, Table 2.7, Table 2.9, Table 4.1} \n", "C.2 Pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid \n", "and far-reaching transitions in energy, land, urban and infrastructure (including transport and \n", "buildings), and industrial systems (high confidence). These systems transitions are unprecedented \n", "in terms of scale, but not necessarily in terms of speed, and imply deep emissions reductions in all \n", "sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those \n", "options (medium confidence). {2.3, 2.4, 2.5, 4.2, 4.3, 4.4, 4.5}\n", "C.2.1 Pathways that limit global warming to 1.5°C with no or limited overshoot show system changes that are more rapid and \n", "pronounced over the next two decades than in 2°C pathways (high confidence). The rates of system changes associated \n", "with limiting global warming to 1.5°C with no or limited overshoot have occurred in the past within specific sectors, \n", "technologies and spatial contexts, but there is no documented historic precedent for their scale (medium confidence). \n", "{2.3.3, 2.3.4, 2.4, 2.5, 4.2.1, 4.2.2, Cross-Chapter Box 11 in Chapter 4} \n", "C.2.2 In energy systems, modelled global pathways (considered in the literature) limiting global warming to 1.5°C with no or \n", "limited overshoot (for more details see Figure SPM.3b) generally meet energy service demand with lower energy use, \n", "including through enhanced energy efficiency, and show faster electrification of energy end use compared to 2°C (high \n", "confidence). In 1.5°C pathways with no or limited overshoot, low-emission energy sources are projected to have a higher \n", "share, compared with 2°C pathways, particularly before 2050 (high confidence). In 1.5°C pathways with no or limited \n", "overshoot, renewables are projected to supply 70–85% (interquartile range) of electricity in 2050 (high confidence). In \n", "electricity generation, shares of nuclear and fossil fuels with carbon dioxide capture and storage (CCS) are modelled to \n", "increase in most 1.5°C pathways with no or limited overshoot. In modelled 1.5°C pathways with limited or no overshoot, \n", "the use of CCS would allow the electricity generation share of gas to be approximately 8% (3–11% interquartile range) \n", "of global electricity in 2050, while the use of coal shows a steep reduction in all pathways and would be reduced to close \n", "to 0% (0–2% interquartile range) of electricity (high confidence). While acknowledging the challenges, and differences \n", "between the options and national circumstances, political, economic, social and technical feasibility of solar energy, wind \n", "energy and electricity storage technologies have substantially improved over the past few years (high confidence). These \n", "improvements signal a potential system transition in electricity generation. (Figure SPM.3b) {2.4.1, 2.4.2, Figure 2.1, Table \n", "2.6, Table 2.7, Cross-Chapter Box 6 in Chapter 3, 4.2.1, 4.3.1, 4.3.3, 4.5.2}\n", "C.2.3 CO2 emissions from industry in pathways limiting global warming to 1.5°C with no or limited overshoot are projected to \n", "be about 65–90% (interquartile range) lower in 2050 relative to 2010, as compared to 50–80% for global warming of \n", "2°C (medium confidence). Such reductions can be achieved through combinations of new and existing technologies and \n", "practices, including electrification, hydrogen, sustainable bio-based feedstocks, product substitution, and carbon capture, \n", "utilization and storage (CCUS). These options are technically proven at various scales but their large-scale deployment \n", "may be limited by economic, financial, human capacity and institutional constraints in specific contexts, and specific \n", "characteristics of large-scale industrial installations. In industry, emissions reductions by energy and process efficiency \n", "by themselves are insufficient for limiting warming to 1.5°C with no or limited overshoot (high confidence). {2.4.3, 4.2.1, \n", "Table 4.1, Table 4.3, 4.3.3, 4.3.4, 4.5.2}\n", "C.2.4 The urban and infrastructure system transition consistent with limiting global warming to 1.5°C with no or limited overshoot \n", "would imply, for example, changes in land and urban planning practices, as well as deeper emissions reductions in transport \n", "and buildings compared to pathways that limit global warming below 2°C (medium confidence). Technical measures \n", "SPMSummary for Policymakers16and practices enabling deep emissions reductions include various energy efficiency options. In pathways limiting global \n", "warming to 1.5°C with no or limited overshoot, the electricity share of energy demand in buildings would be about 55–75% \n", "in 2050 compared to 50–70% in 2050 for 2°C global warming (medium confidence). In the transport sector, the share of \n", "low-emission final energy would rise from less than 5% in 2020 to about 35–65% in 2050 compared to 25–45% for 2°C \n", "of global warming (medium confidence). Economic, institutional and socio-cultural barriers may inhibit these urban and \n", "infrastructure system transitions, depending on national, regional and local circumstances, capabilities and the availability \n", "of capital (high confidence). {2.3.4, 2.4.3, 4.2.1, Table 4.1, 4.3.3, 4.5.2}\n", "C.2.5 Transitions in global and regional land use are found in all pathways limiting global warming to 1.5°C with no or limited \n", "overshoot, but their scale depends on the pursued mitigation portfolio. Model pathways that limit global warming to 1.5°C \n", "with no or limited overshoot project a 4 million km2 reduction to a 2.5 million km2 increase of non-pasture agricultural land \n", "for food and feed crops and a 0.5–11 million km2 reduction of pasture land, to be converted into a 0–6 million km2 increase \n", "of agricultural land for energy crops and a 2 million km2 reduction to 9.5 million km2 increase in forests by 2050 relative \n", "to 2010 (medium confidence).16 Land-use transitions of similar magnitude can be observed in modelled 2°C pathways \n", "(medium confidence). Such large transitions pose profound challenges for sustainable management of the various demands \n", "on land for human settlements, food, livestock feed, fibre, bioenergy, carbon storage, biodiversity and other ecosystem \n", "services (high confidence). Mitigation options limiting the demand for land include sustainable intensification of land-use \n", "practices, ecosystem restoration and changes towards less resource-intensive diets (high confidence). The implementation \n", "of land-based mitigation options would require overcoming socio-economic, institutional, technological, financing and \n", "environmental barriers that differ across regions (high confidence). {2.4.4, Figure 2.24, 4.3.2, 4.3.7, 4.5.2, Cross-Chapter \n", "Box 7 in Chapter 3}\n", "C.2.6 Additional annual average energy-related investments for the period 2016 to 2050 in pathways limiting warming to \n", "1.5°C compared to pathways without new climate policies beyond those in place today are estimated to be around 830 \n", "billion USD2010 (range of 150 billion to 1700 billion USD2010 across six models17). This compares to total annual average \n", "energy supply investments in 1.5°C pathways of 1460 to 3510 billion USD2010 and total annual average energy demand \n", "investments of 640 to 910 billion USD2010 for the period 2016 to 2050. Total energy-related investments increase by \n", "about 12% (range of 3% to 24%) in 1.5°C pathways relative to 2°C pathways. Annual investments in low-carbon energy \n", "technologies and energy efficiency are upscaled by roughly a factor of six (range of factor of 4 to 10) by 2050 compared to \n", "2015 (medium confidence). {2.5.2, Box 4.8, Figure 2.27}\n", "C.2.7 Modelled pathways limiting global warming to 1.5°C with no or limited overshoot project a wide range of global average \n", "discounted marginal abatement costs over the 21st century. They are roughly 3-4 times higher than in pathways limiting \n", "global warming to below 2°C (high confidence). The economic literature distinguishes marginal abatement costs from total \n", "mitigation costs in the economy. The literature on total mitigation costs of 1.5°C mitigation pathways is limited and was \n", "not assessed in this Report. Knowledge gaps remain in the integrated assessment of the economy-wide costs and benefits \n", "of mitigation in line with pathways limiting warming to 1.5°C. {2.5.2; 2.6; Figure 2.26}\n", "16 The projected land-use changes presented are not deployed to their upper limits simultaneously in a single pathway.\n", "17 Including two pathways limiting warming to 1.5°C with no or limited overshoot and four pathways with higher overshoot.\n", "SPM Summary for Policymakers17C.3 All pathways that limit global warming to 1.5°C with limited or no overshoot project the use of \n", "carbon dioxide removal (CDR) on the order of 100–1000 GtCO2 over the 21st century. CDR would \n", "be used to compensate for residual emissions and, in most cases, achieve net negative emissions \n", "to return global warming to 1.5°C following a peak (high confidence). CDR deployment of several \n", "hundreds of GtCO2 is subject to multiple feasibility and sustainability constraints (high confidence). \n", "Significant near-term emissions reductions and measures to lower energy and land demand can \n", "limit CDR deployment to a few hundred GtCO2 without reliance on bioenergy with carbon capture \n", "and storage (BECCS) (high confidence). {2.3, 2.4, 3.6.2, 4.3, 5.4} \n", "C.3.1 Existing and potential CDR measures include afforestation and reforestation, land restoration and soil carbon sequestration, \n", "BECCS, direct air carbon capture and storage (DACCS), enhanced weathering and ocean alkalinization. These differ widely \n", "in terms of maturity, potentials, costs, risks, co-benefits and trade-offs (high confidence). To date, only a few published \n", "pathways include CDR measures other than afforestation and BECCS. {2.3.4, 3.6.2, 4.3.2, 4.3.7}\n", "C.3.2 In pathways limiting global warming to 1.5°C with limited or no overshoot, BECCS deployment is projected to range from \n", "0–1, 0–8, and 0–16 GtCO2 yr−1 in 2030, 2050, and 2100, respectively, while agriculture, forestry and land-use (AFOLU) \n", "related CDR measures are projected to remove 0–5, 1–11, and 1–5 GtCO2 yr−1 in these years (medium confidence). The \n", "upper end of these deployment ranges by mid-century exceeds the BECCS potential of up to 5 GtCO2 yr−1 and afforestation \n", "potential of up to 3.6 GtCO2 yr−1 assessed based on recent literature (medium confidence). Some pathways avoid BECCS \n", "deployment completely through demand-side measures and greater reliance on AFOLU-related CDR measures (medium \n", "confidence). The use of bioenergy can be as high or even higher when BECCS is excluded compared to when it is included \n", "due to its potential for replacing fossil fuels across sectors (high confidence). (Figure SPM.3b) {2.3.3, 2.3.4, 2.4.2, 3.6.2, \n", "4.3.1, 4.2.3, 4.3.2, 4.3.7, 4.4.3, Table 2.4}\n", "C.3.3 Pathways that overshoot 1.5°C of global warming rely on CDR exceeding residual CO2 emissions later in the century to \n", "return to below 1.5°C by 2100, with larger overshoots requiring greater amounts of CDR (Figure SPM.3b) (high confidence). \n", "Limitations on the speed, scale, and societal acceptability of CDR deployment hence determine the ability to return global \n", "warming to below 1.5°C following an overshoot. Carbon cycle and climate system understanding is still limited about the \n", "effectiveness of net negative emissions to reduce temperatures after they peak (high confidence). {2.2, 2.3.4, 2.3.5, 2.6, \n", "4.3.7, 4.5.2, Table 4.11}\n", "C.3.4 Most current and potential CDR measures could have significant impacts on land, energy, water or nutrients if deployed \n", "at large scale (high confidence). Afforestation and bioenergy may compete with other land uses and may have significant \n", "impacts on agricultural and food systems, biodiversity, and other ecosystem functions and services (high confidence). \n", "Effective governance is needed to limit such trade-offs and ensure permanence of carbon removal in terrestrial, geological \n", "and ocean reservoirs (high confidence). Feasibility and sustainability of CDR use could be enhanced by a portfolio of options \n", "deployed at substantial, but lesser scales, rather than a single option at very large scale (high confidence). (Figure SPM.3b) \n", "{2.3.4, 2.4.4, 2.5.3, 2.6, 3.6.2, 4.3.2, 4.3.7, 4.5.2, 5.4.1, 5.4.2; Cross-Chapter Boxes 7 and 8 in Chapter 3, Table 4.11, Table \n", "5.3, Figure 5.3}\n", "C.3.5 Some AFOLU-related CDR measures such as restoration of natural ecosystems and soil carbon sequestration could provide \n", "co-benefits such as improved biodiversity, soil quality, and local food security. If deployed at large scale, they would \n", "require governance systems enabling sustainable land management to conserve and protect land carbon stocks and other \n", "ecosystem functions and services (medium confidence). (Figure SPM.4) {2.3.3, 2.3.4, 2.4.2, 2.4.4, 3.6.2, 5.4.1, Cross-Chapter \n", "Boxes 3 in Chapter 1 and 7 in Chapter 3, 4.3.2, 4.3.7, 4.4.1, 4.5.2, Table 2.4}\n", "SPMSummary for Policymakers18D. Strengthening the Global Response in the Context of Sustainable \n", "Development and Efforts to Eradicate Poverty\n", "D.1 Estimates of the global emissions outcome of current nationally stated mitigation ambitions as \n", "submitted under the Paris Agreement would lead to global greenhouse gas emissions18 in 2030 \n", "of 52–58 GtCO2eq yr−1 (medium confidence). Pathways reflecting these ambitions would not limit \n", "global warming to 1.5°C, even if supplemented by very challenging increases in the scale and \n", "ambition of emissions reductions after 2030 (high confidence). Avoiding overshoot and reliance \n", "on future large-scale deployment of carbon dioxide removal (CDR) can only be achieved if global \n", "CO2 emissions start to decline well before 2030 (high confidence). {1.2, 2.3, 3.3, 3.4, 4.2, 4.4, Cross-\n", "Chapter Box 11 in Chapter 4} \n", "D.1.1 Pathways that limit global warming to 1.5°C with no or limited overshoot show clear emission reductions by 2030 (high \n", "confidence). All but one show a decline in global greenhouse gas emissions to below 35 GtCO2eq yr−1 in 2030, and half of \n", "available pathways fall within the 25–30 GtCO2eq yr−1 range (interquartile range), a 40–50% reduction from 2010 levels \n", "(high confidence). Pathways reflecting current nationally stated mitigation ambition until 2030 are broadly consistent \n", "with cost-effective pathways that result in a global warming of about 3°C by 2100, with warming continuing afterwards \n", "(medium confidence). {2.3.3, 2.3.5, Cross-Chapter Box 11 in Chapter 4, 5.5.3.2}\n", "D.1.2 Overshoot trajectories result in higher impacts and associated challenges compared to pathways that limit global warming \n", "to 1.5°C with no or limited overshoot (high confidence). Reversing warming after an overshoot of 0.2°C or larger during \n", "this century would require upscaling and deployment of CDR at rates and volumes that might not be achievable given \n", "considerable implementation challenges (medium confidence). {1.3.3, 2.3.4, 2.3.5, 2.5.1, 3.3, 4.3.7, Cross-Chapter Box 8 in \n", "Chapter 3, Cross-Chapter Box 11 in Chapter 4}\n", "D.1.3 The lower the emissions in 2030, the lower the challenge in limiting global warming to 1.5°C after 2030 with no or limited \n", "overshoot (high confidence). The challenges from delayed actions to reduce greenhouse gas emissions include the risk of \n", "cost escalation, lock-in in carbon-emitting infrastructure, stranded assets, and reduced flexibility in future response options \n", "in the medium to long term (high confidence). These may increase uneven distributional impacts between countries at \n", "different stages of development (medium confidence). {2.3.5, 4.4.5, 5.4.2}\n", "D.2 The avoided climate change impacts on sustainable development, eradication of poverty and reducing \n", "inequalities would be greater if global warming were limited to 1.5°C rather than 2°C, if mitigation \n", "and adaptation synergies are maximized while trade-offs are minimized (high confidence). {1.1, 1.4, \n", "2.5, 3.3, 3.4, 5.2, Table 5.1}\n", "D.2.1 Climate change impacts and responses are closely linked to sustainable development which balances social well-being, \n", "economic prosperity and environmental protection. The United Nations Sustainable Development Goals (SDGs), adopted in \n", "2015, provide an established framework for assessing the links between global warming of 1.5°C or 2°C and development \n", "goals that include poverty eradication, reducing inequalities, and climate action. (high confidence) {Cross-Chapter Box 4 in \n", "Chapter 1, 1.4, 5.1}\n", "D.2.2 The consideration of ethics and equity can help address the uneven distribution of adverse impacts associated with \n", "1.5°C and higher levels of global warming, as well as those from mitigation and adaptation, particularly for poor and \n", "disadvantaged populations, in all societies (high confidence). {1.1.1, 1.1.2, 1.4.3, 2.5.3, 3.4.10, 5.1, 5.2, 5.3. 5.4, Cross-\n", "Chapter Box 4 in Chapter 1, Cross-Chapter Boxes 6 and 8 in Chapter 3, and Cross-Chapter Box 12 in Chapter 5}\n", "D.2.3 Mitigation and adaptation consistent with limiting global warming to 1.5°C are underpinned by enabling conditions, assessed \n", "in this Report across the geophysical, environmental-ecological, technological, economic, socio-cultural and institutional \n", "18 GHG emissions have been aggregated with 100-year GWP values as introduced in the IPCC Second Assessment Report.\n", "SPM Summary for Policymakers19dimensions of feasibility. Strengthened multilevel governance, institutional capacity, policy instruments, technological \n", "innovation and transfer and mobilization of finance, and changes in human behaviour and lifestyles are enabling conditions \n", "that enhance the feasibility of mitigation and adaptation options for 1.5°C-consistent systems transitions. (high confidence) \n", "{1.4, Cross-Chapter Box 3 in Chapter 1, 2.5.1, 4.4, 4.5, 5.6}\n", "D.3 Adaptation options specific to national contexts, if carefully selected together with enabling \n", "conditions, will have benefits for sustainable development and poverty reduction with global \n", "warming of 1.5°C, although trade-offs are possible (high confidence). {1.4, 4.3, 4.5}\n", "D.3.1 Adaptation options that reduce the vulnerability of human and natural systems have many synergies with sustainable \n", "development, if well managed, such as ensuring food and water security, reducing disaster risks, improving health \n", "conditions, maintaining ecosystem services and reducing poverty and inequality (high confidence). Increasing investment \n", "in physical and social infrastructure is a key enabling condition to enhance the resilience and the adaptive capacities \n", "of societies. These benefits can occur in most regions with adaptation to 1.5°C of global warming (high confidence). \n", "{1.4.3, 4.2.2, 4.3.1, 4.3.2, 4.3.3, 4.3.5, 4.4.1, 4.4.3, 4.5.3, 5.3.1, 5.3.2}\n", "D.3.2 Adaptation to 1.5°C global warming can also result in trade-offs or maladaptations with adverse impacts for sustainable \n", "development. For example, if poorly designed or implemented, adaptation projects in a range of sectors can increase \n", "greenhouse gas emissions and water use, increase gender and social inequality, undermine health conditions, and encroach \n", "on natural ecosystems (high confidence). These trade-offs can be reduced by adaptations that include attention to poverty \n", "and sustainable development (high confidence). {4.3.2, 4.3.3, 4.5.4, 5.3.2; Cross-Chapter Boxes 6 and 7 in Chapter 3} \n", "D.3.3 A mix of adaptation and mitigation options to limit global warming to 1.5°C, implemented in a participatory and integrated \n", "manner, can enable rapid, systemic transitions in urban and rural areas (high confidence). These are most effective when \n", "aligned with economic and sustainable development, and when local and regional governments and decision makers are \n", "supported by national governments (medium confidence). {4.3.2, 4.3.3, 4.4.1, 4.4.2}\n", "D.3.4 Adaptation options that also mitigate emissions can provide synergies and cost savings in most sectors and system \n", "transitions, such as when land management reduces emissions and disaster risk, or when low-carbon buildings are also \n", "designed for efficient cooling. Trade-offs between mitigation and adaptation, when limiting global warming to 1.5°C, \n", "such as when bioenergy crops, reforestation or afforestation encroach on land needed for agricultural adaptation, can \n", "undermine food security, livelihoods, ecosystem functions and services and other aspects of sustainable development. (high \n", "confidence) {3.4.3, 4.3.2, 4.3.4, 4.4.1, 4.5.2, 4.5.3, 4.5.4}\n", "D.4 Mitigation options consistent with 1.5°C pathways are associated with multiple synergies and trade-\n", "offs across the Sustainable Development Goals (SDGs). While the total number of possible synergies \n", "exceeds the number of trade-offs, their net effect will depend on the pace and magnitude of changes, \n", "the composition of the mitigation portfolio and the management of the transition. (high confidence) \n", "(Figure SPM.4) {2.5, 4.5, 5.4} \n", "D.4.1 1.5°C pathways have robust synergies particularly for the SDGs 3 (health), 7 (clean energy), 11 (cities and communities), 12 \n", "(responsible consumption and production) and 14 (oceans) (very high confidence). Some 1.5°C pathways show potential \n", "trade-offs with mitigation for SDGs 1 (poverty), 2 (hunger), 6 (water) and 7 (energy access), if not managed carefully (high \n", "confidence). (Figure SPM.4) {5.4.2; Figure 5.4, Cross-Chapter Boxes 7 and 8 in Chapter 3} \n", "D.4.2 1.5°C pathways that include low energy demand (e.g., see P1 in Figure SPM.3a and SPM.3b), low material consumption, \n", "and low GHG-intensive food consumption have the most pronounced synergies and the lowest number of trade-offs with \n", "respect to sustainable development and the SDGs (high confidence). Such pathways would reduce dependence on CDR. In \n", "modelled pathways, sustainable development, eradicating poverty and reducing inequality can support limiting warming to \n", "1.5°C (high confidence). (Figure SPM.3b, Figure SPM.4) {2.4.3, 2.5.1, 2.5.3, Figure 2.4, Figure 2.28, 5.4.1, 5.4.2, Figure 5.4} \n", "SPMSummary for Policymakers20Indicative linkages between mitigation options and sustainable \n", "development using SDGs (The linkages do not show costs and benefits)\n", "Mitigation options deployed in each sector can be associated with potential positive effects (synergies) or \n", "negative effects (trade-offs) with the Sustainable Development Goals (SDGs). The degree to which this \n", "potential is realized will depend on the selected portfolio of mitigation options, mitigation policy design, \n", "and local circumstances and context. Particularly in the energy-demand sector, the potential for synergies is \n", "larger than for trade-offs. The bars group individually assessed options by level of confidence and take into \n", "account the relative strength of the assessed mitigation-SDG connections.\n", "The overall size of the coloured bars depict the relative \n", "potential for synergies and trade-offs between the sectoral \n", "mitigation options and the SDGs.Length shows strength of connection\n", "Energy Supply Land\n", "Trade-offs Synergies Trade-offs Synergies Trade-offs Synergies\n", "The shades depict the level of confidence of the \n", "assessed potential for Trade-offs/Synergies.\n", "Very High LowShades show level of confidence\n", "Energy Demand \n", "SDG1\n", "No Poverty\n", "SDG2\n", "Zero Hunger\n", "SDG 3\n", "Good Health\n", "and Well-being\n", "SDG 4\n", "Quality\n", "Education\n", "SDG 5\n", "Gender\n", "Equality\n", "SDG 6\n", "Clean Water\n", "and Sanitation\n", "SDG 7\n", "Affordable and\n", "Clean Energy\n", "SDG 8\n", "Decent Work\n", "and Economic\n", "Growth\n", "SDG 9\n", "Industry,\n", "Innovation and\n", "Infrastructure\n", "SDG 10\n", "Reduced\n", "Inequalities\n", "SDG 11\n", "Sustainable\n", "Cities and\n", "Communities\n", "SDG 12\n", "Responsible\n", "Consumption\n", "and Production\n", "SDG 14\n", "Life Below\n", "Water\n", "SDG 15\n", "Life on Land\n", "SDG 16\n", "Peace, Justice\n", "and Strong\n", "Institutions\n", "SDG 17\n", "Partnerships for\n", " the Goals\n", "SPM Summary for Policymakers21D.4.3 1.5°C and 2°C modelled pathways often rely on the deployment of large-scale land-related measures like afforestation \n", "and bioenergy supply, which, if poorly managed, can compete with food production and hence raise food security concerns \n", "(high confidence). The impacts of carbon dioxide removal (CDR) options on SDGs depend on the type of options and the \n", "scale of deployment (high confidence). If poorly implemented, CDR options such as BECCS and AFOLU options would lead \n", "to trade-offs. Context-relevant design and implementation requires considering people’s needs, biodiversity, and other \n", "sustainable development dimensions (very high confidence). (Figure SPM.4) {5.4.1.3, Cross-Chapter Box 7 in Chapter 3} \n", "D.4.4 Mitigation consistent with 1.5°C pathways creates risks for sustainable development in regions with high dependency on \n", "fossil fuels for revenue and employment generation (high confidence). Policies that promote diversification of the economy \n", "and the energy sector can address the associated challenges (high confidence). {5.4.1.2, Box 5.2} \n", "D.4.5 Redistributive policies across sectors and populations that shield the poor and vulnerable can resolve trade-offs for a range \n", "of SDGs, particularly hunger, poverty and energy access. Investment needs for such complementary policies are only a small \n", "fraction of the overall mitigation investments in 1.5°C pathways. (high confidence) {2.4.3, 5.4.2, Figure 5.5} \n", "D.5 Limiting the risks from global warming of 1.5°C in the context of sustainable development and \n", "poverty eradication implies system transitions that can be enabled by an increase of adaptation \n", "and mitigation investments, policy instruments, the acceleration of technological innovation and \n", "behaviour changes (high confidence). {2.3, 2.4, 2.5, 3.2, 4.2, 4.4, 4.5, 5.2, 5.5, 5.6}\n", "D.5.1 Directing finance towards investment in infrastructure for mitigation and adaptation could provide additional resources. \n", "This could involve the mobilization of private funds by institutional investors, asset managers and development or \n", "investment banks, as well as the provision of public funds. Government policies that lower the risk of low-emission and \n", "adaptation investments can facilitate the mobilization of private funds and enhance the effectiveness of other public \n", "policies. Studies indicate a number of challenges, including access to finance and mobilization of funds. (high confidence) \n", "{2.5.1, 2.5.2, 4.4.5} \n", "D.5.2 Adaptation finance consistent with global warming of 1.5°C is difficult to quantify and compare with 2°C. Knowledge \n", "gaps include insufficient data to calculate specific climate resilience-enhancing investments from the provision of currently \n", "underinvested basic infrastructure. Estimates of the costs of adaptation might be lower at global warming of 1.5°C than for \n", "2°C. Adaptation needs have typically been supported by public sector sources such as national and subnational government \n", "budgets, and in developing countries together with support from development assistance, multilateral development banks, \n", "and United Nations Framework Convention on Climate Change channels (medium confidence). More recently there is a Figure SPM.4 | Potential synergies and trade-offs between the sectoral portfolio of climate change mitigation options and the Sustainable Development Goals \n", "(SDGs). The SDGs serve as an analytical framework for the assessment of the different sustainable development dimensions, which extend beyond the time frame \n", "of the 2030 SDG targets. The assessment is based on literature on mitigation options that are considered relevant for 1.5°C. The assessed strength of the SDG \n", "interactions is based on the qualitative and quantitative assessment of individual mitigation options listed in Table 5.2. For each mitigation option, the strength of \n", "the SDG-connection as well as the associated confidence of the underlying literature (shades of green and red) was assessed. The strength of positive connections \n", "(synergies) and negative connections (trade-offs) across all individual options within a sector (see Table 5.2) are aggregated into sectoral potentials for the whole \n", "mitigation portfolio. The (white) areas outside the bars, which indicate no interactions, have low confidence due to the uncertainty and limited number of studies \n", "exploring indirect effects. The strength of the connection considers only the effect of mitigation and does not include benefits of avoided impacts. SDG 13 (climate \n", "action) is not listed because mitigation is being considered in terms of interactions with SDGs and not vice versa. The bars denote the strength of the connection, \n", "and do not consider the strength of the impact on the SDGs. The energy demand sector comprises behavioural responses, fuel switching and efficiency options in \n", "the transport, industry and building sector as well as carbon capture options in the industry sector. Options assessed in the energy supply sector comprise biomass \n", "and non-biomass renewables, nuclear, carbon capture and storage (CCS) with bioenergy, and CCS with fossil fuels. Options in the land sector comprise agricultural \n", "and forest options, sustainable diets and reduced food waste, soil sequestration, livestock and manure management, reduced deforestation, afforestation and \n", "reforestation, and responsible sourcing. In addition to this figure, options in the ocean sector are discussed in the underlying report. {5.4, Table 5.2, Figure 5.2}\n", "Information about the net impacts of mitigation on sustainable development in 1.5°C pathways is available only for a limited number of SDGs and mitigation \n", "options. Only a limited number of studies have assessed the benefits of avoided climate change impacts of 1.5°C pathways for the SDGs, and the co-effects \n", "of adaptation for mitigation and the SDGs. The assessment of the indicative mitigation potentials in Figure SPM.4 is a step further from AR5 towards a more \n", "comprehensive and integrated assessment in the future.\n", "SPMSummary for Policymakers22growing understanding of the scale and increase in non-governmental organizations and private funding in some regions \n", "(medium confidence). Barriers include the scale of adaptation financing, limited capacity and access to adaptation finance \n", "(medium confidence). {4.4.5, 4.6} \n", "D.5.3 Global model pathways limiting global warming to 1.5°C are projected to involve the annual average investment needs \n", "in the energy system of around 2.4 trillion USD2010 between 2016 and 2035, representing about 2.5% of the world GDP \n", "(medium confidence). {4.4.5, Box 4.8}\n", "D.5.4 Policy tools can help mobilize incremental resources, including through shifting global investments and savings and \n", "through market and non-market based instruments as well as accompanying measures to secure the equity of the \n", "transition, acknowledging the challenges related with implementation, including those of energy costs, depreciation of \n", "assets and impacts on international competition, and utilizing the opportunities to maximize co-benefits (high confidence). \n", "{1.3.3, 2.3.4, 2.3.5, 2.5.1, 2.5.2, Cross-Chapter Box 8 in Chapter 3, Cross-Chapter Box 11 in Chapter 4, 4.4.5, 5.5.2}\n", "D.5.5 The systems transitions consistent with adapting to and limiting global warming to 1.5°C include the widespread adoption \n", "of new and possibly disruptive technologies and practices and enhanced climate-driven innovation. These imply enhanced \n", "technological innovation capabilities, including in industry and finance. Both national innovation policies and international \n", "cooperation can contribute to the development, commercialization and widespread adoption of mitigation and adaptation \n", "technologies. Innovation policies may be more effective when they combine public support for research and development \n", "with policy mixes that provide incentives for technology diffusion. (high confidence) {4.4.4, 4.4.5}. \n", "D.5.6 Education, information, and community approaches, including those that are informed by indigenous knowledge and local \n", "knowledge, can accelerate the wide-scale behaviour changes consistent with adapting to and limiting global warming to \n", "1.5°C. These approaches are more effective when combined with other policies and tailored to the motivations, capabilities \n", "and resources of specific actors and contexts (high confidence). Public acceptability can enable or inhibit the implementation \n", "of policies and measures to limit global warming to 1.5°C and to adapt to the consequences. Public acceptability depends \n", "on the individual’s evaluation of expected policy consequences, the perceived fairness of the distribution of these \n", "consequences, and perceived fairness of decision procedures (high confidence). {1.1, 1.5, 4.3.5, 4.4.1, 4.4.3, Box 4.3, 5.5.3, \n", "5.6.5} \n", "D.6 Sustainable development supports, and often enables, the fundamental societal and systems \n", "transitions and transformations that help limit global warming to 1.5°C. Such changes facilitate the \n", "pursuit of climate-resilient development pathways that achieve ambitious mitigation and adaptation \n", "in conjunction with poverty eradication and efforts to reduce inequalities (high confidence). {Box 1.1, \n", "1.4.3, Figure 5.1, 5.5.3, Box 5.3} \n", "D.6.1 Social justice and equity are core aspects of climate-resilient development pathways that aim to limit global warming to \n", "1.5°C as they address challenges and inevitable trade-offs, widen opportunities, and ensure that options, visions, and values \n", "are deliberated, between and within countries and communities, without making the poor and disadvantaged worse off \n", "(high confidence). {5.5.2, 5.5.3, Box 5.3, Figure 5.1, Figure 5.6, Cross-Chapter Boxes 12 and 13 in Chapter 5}\n", "D.6.2 The potential for climate-resilient development pathways differs between and within regions and nations, due to different \n", "development contexts and systemic vulnerabilities (very high confidence). Efforts along such pathways to date have been \n", "limited (medium confidence) and enhanced efforts would involve strengthened and timely action from all countries and \n", "non-state actors (high confidence). {5.5.1, 5.5.3, Figure 5.1}\n", "D.6.3 Pathways that are consistent with sustainable development show fewer mitigation and adaptation challenges and are \n", "associated with lower mitigation costs. The large majority of modelling studies could not construct pathways characterized \n", "by lack of international cooperation, inequality and poverty that were able to limit global warming to 1.5°C. (high \n", "confidence) {2.3.1, 2.5.1, 2.5.3, 5.5.2}\n", "SPM Summary for Policymakers23D.7 Strengthening the capacities for climate action of national and sub-national authorities, civil society, \n", "the private sector, indigenous peoples and local communities can support the implementation of \n", "ambitious actions implied by limiting global warming to 1.5°C (high confidence). International \n", "cooperation can provide an enabling environment for this to be achieved in all countries and for all \n", "people, in the context of sustainable development. International cooperation is a critical enabler for \n", "developing countries and vulnerable regions (high confidence). {1.4, 2.3, 2.5, 4.2, 4.4, 4.5, 5.3, 5.4, 5.5, \n", "5.6, 5, Box 4.1, Box 4.2, Box 4.7, Box 5.3, Cross-Chapter Box 9 in Chapter 4, Cross-Chapter Box 13 in \n", "Chapter 5}\n", "D.7.1 Partnerships involving non-state public and private actors, institutional investors, the banking system, civil society and \n", "scientific institutions would facilitate actions and responses consistent with limiting global warming to 1.5°C (very high \n", "confidence). {1.4, 4.4.1, 4.2.2, 4.4.3, 4.4.5, 4.5.3, 5.4.1, 5.6.2, Box 5.3}.\n", "D.7.2 Cooperation on strengthened accountable multilevel governance that includes non-state actors such as industry, civil \n", "society and scientific institutions, coordinated sectoral and cross-sectoral policies at various governance levels, gender-\n", "sensitive policies, finance including innovative financing, and cooperation on technology development and transfer can \n", "ensure participation, transparency, capacity building and learning among different players (high confidence). {2.5.1, 2.5.2, \n", "4.2.2, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.5.3, Cross-Chapter Box 9 in Chapter 4, 5.3.1, 5.5.3, Cross-Chapter Box 13 in Chapter \n", "5, 5.6.1, 5.6.3}\n", "D.7.3 International cooperation is a critical enabler for developing countries and vulnerable regions to strengthen their action for \n", "the implementation of 1.5°C-consistent climate responses, including through enhancing access to finance and technology \n", "and enhancing domestic capacities, taking into account national and local circumstances and needs (high confidence). \n", "{2.3.1, 2.5.1, 4.4.1, 4.4.2, 4.4.4, 4.4.5, 5.4.1 5.5.3, 5.6.1, Box 4.1, Box 4.2, Box 4.7}.\n", "D.7.4 Collective efforts at all levels, in ways that reflect different circumstances and capabilities, in the pursuit of limiting global \n", "warming to 1.5°C, taking into account equity as well as effectiveness, can facilitate strengthening the global response to \n", "climate change, achieving sustainable development and eradicating poverty (high confidence). {1.4.2, 2.3.1, 2.5.1, 2.5.2, \n", "2.5.3, 4.2.2, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.5.3, 5.3.1, 5.4.1, 5.5.3, 5.6.1, 5.6.2, 5.6.3}\n", "SPMSummary for Policymakers24Box SPM.1: Core Concepts Central to this Special Report \n", "Global mean surface temperature (GMST): Estimated global average of near-surface air temperatures over land and \n", "sea ice, and sea surface temperatures over ice-free ocean regions, with changes normally expressed as departures from a \n", "value over a specified reference period. When estimating changes in GMST, near-surface air temperature over both land \n", "and oceans are also used.19 {1.2.1.1} \n", "Pre-industrial: The multi-century period prior to the onset of large-scale industrial activity around 1750. The reference \n", "period 1850–1900 is used to approximate pre-industrial GMST. {1.2.1.2} \n", "Global warming: The estimated increase in GMST averaged over a 30-year period, or the 30-year period centred on a \n", "particular year or decade, expressed relative to pre-industrial levels unless otherwise specified. For 30-year periods that \n", "span past and future years, the current multi-decadal warming trend is assumed to continue. {1.2.1}\n", "Net zero CO2 emissions: Net zero carbon dioxide (CO2) emissions are achieved when anthropogenic CO2 emissions are \n", "balanced globally by anthropogenic CO2 removals over a specified period. \n", "Carbon dioxide removal (CDR): Anthropogenic activities removing CO2 from the atmosphere and durably storing it in \n", "geological, terrestrial, or ocean reservoirs, or in products. It includes existing and potential anthropogenic enhancement of \n", "biological or geochemical sinks and direct air capture and storage, but excludes natural CO2 uptake not directly caused by \n", "human activities.\n", "Total carbon budget: Estimated cumulative net global anthropogenic CO2 emissions from the pre-industrial period \n", "to the time that anthropogenic CO2 emissions reach net zero that would result, at some probability, in limiting global \n", "warming to a given level, accounting for the impact of other anthropogenic emissions. {2.2.2} \n", "Remaining carbon budget: Estimated cumulative net global anthropogenic CO2 emissions from a given start date to the \n", "time that anthropogenic CO2 emissions reach net zero that would result, at some probability, in limiting global warming \n", "to a given level, accounting for the impact of other anthropogenic emissions. {2.2.2}\n", "Temperature overshoot: The temporary exceedance of a specified level of global warming. \n", "Emission pathways: In this Summary for Policymakers, the modelled trajectories of global anthropogenic emissions over \n", "the 21st century are termed emission pathways. Emission pathways are classified by their temperature trajectory over \n", "the 21st century: pathways giving at least 50% probability based on current knowledge of limiting global warming to \n", "below 1.5°C are classified as ‘no overshoot’; those limiting warming to below 1.6°C and returning to 1.5°C by 2100 are \n", "classified as ‘1.5°C limited-overshoot’; while those exceeding 1.6°C but still returning to 1.5°C by 2100 are classified as \n", "‘higher-overshoot’.\n", "Impacts: Effects of climate change on human and natural systems. Impacts can have beneficial or adverse outcomes \n", "for livelihoods, health and well-being, ecosystems and species, services, infrastructure, and economic, social and cultural \n", "assets.\n", "Risk: The potential for adverse consequences from a climate-related hazard for human and natural systems, resulting \n", "from the interactions between the hazard and the vulnerability and exposure of the affected system. Risk integrates \n", "the likelihood of exposure to a hazard and the magnitude of its impact. Risk also can describe the potential for adverse \n", "consequences of adaptation or mitigation responses to climate change. \n", "Climate-resilient development pathways (CRDPs): Trajectories that strengthen sustainable development at multiple \n", "scales and efforts to eradicate poverty through equitable societal and systems transitions and transformations while \n", "reducing the threat of climate change through ambitious mitigation, adaptation and climate resilience. \n", "19 Past IPCC reports, reflecting the literature, have used a variety of approximately equivalent metrics of GMST change.\n" ] } ], "source": [ "# Choisissez une méthode d'extraction du contenu du pdf page à page\n", "\n", "!pip install PyPDF2\n", "\n", "import PyPDF2\n", "\n", "# Chemin du dossier contenant les fichiers PDF\n", "chemin_dossier = \"/content/drive/My Drive/RAG_IPCC\"\n", "\n", "# Liste des fichiers PDF dans le dossier\n", "fichiers_pdf = [f for f in os.listdir(chemin_dossier) if f.endswith('.pdf')]\n", "\n", "# Liste pour stocker le texte extrait de chaque PDF\n", "extracted_text = []\n", "\n", "# Boucle à travers chaque fichier PDF\n", "for pdf in fichiers_pdf:\n", " print(f\"*** PROCESSING FILE : {pdf} ***\")\n", "\n", " # Chemin complet du fichier PDF\n", " chemin_pdf = os.path.join(chemin_dossier, pdf)\n", "\n", " # Ouverture du fichier PDF en mode lecture binaire\n", " with open(chemin_pdf, 'rb') as file:\n", " # Création d'un objet de lecteur PDF\n", " pdf_reader = PyPDF2.PdfReader(file)\n", "\n", " # Boucle à travers chaque page du PDF\n", " for page_num in range(len(pdf_reader.pages)):\n", " # Extraction du texte de la page actuelle\n", " page = pdf_reader.pages[page_num]\n", " text = page.extract_text()\n", "\n", " # Ajout du texte extrait à la liste\n", " extracted_text.append(text)\n", "\n", "# Affichage du texte extrait\n", "for text in extracted_text:\n", " print(text)\n", "\n" ] }, { "cell_type": "markdown", "metadata": { "id": "xAwhuborGHcZ" }, "source": [ "### 3. Création des chunks" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "MRQtDsp8rv8L", "colab": { "base_uri": "https://localhost:8080/" }, "outputId": "4924eeaf-625a-4c90-8dbf-49b7a2a54b5e" }, "outputs": [ { "output_type": "stream", "name": "stdout", "text": [ "\u001b[31mERROR: You must give at least one requirement to install (see \"pip help install\")\u001b[0m\u001b[31m\n", "\u001b[0m['Bonjour', ',', \"aujourd'hui\", \"c'est\", '.', 'le', '26', 'Mars', '2019', 'ça', 'marche', '?']\n", "[\"Bonjour , aujourd'hui c'est .\", 'le 26 Mars 2019 ça', 'marche ?']\n", "[\"Bonjour, aujourd'hui c'est\", ' le 26 Mars 2019 ça marche?']\n" ] }, { "output_type": "stream", "name": "stderr", "text": [ "[nltk_data] Downloading package punkt to /root/nltk_data...\n", "[nltk_data] Package punkt is already up-to-date!\n" ] } ], "source": [ "# Implémentez une fonction de splitting par nombre de mots\n", "!pip install\n", "import re\n", "import nltk\n", "from nltk.tokenize import word_tokenize\n", "nltk.download('punkt')\n", "def splitting_by_numer_of_words(text, chunk_size):\n", " list_text=word_tokenize(text)\n", " print(list_text)\n", " chunks=[]\n", " l=0\n", " str=\"\"\n", " for mot in list_text:\n", " #if re.search('[a-zA-Z0-9]', mot):\n", " l+=1\n", " if l