Editing IPCC:AR6/WGII/SPM (section)

== B: Observed and Projected Impacts and Risks ==

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Since AR5, the knowledge base on observed and projected impacts and risks generated by climate hazards, exposure and vulnerability has increased with impacts attributed to climate change and key risks identified across the report. Impacts and risks are expressed in terms of their damages, harms, economic, and non-economic losses. Risks from observed vulnerabilities and responses to climate change are highlighted. Risks are projected for the near-term (2021–2040), the mid (2041–2060) and long term (2081–2100), at different global warming levels and for pathways that overshoot 1.5°C global warming level for multiple decades [[#footnote-023|27]] . Complex risks result from multiple climate hazards occurring concurrently, and from multiple risks interacting, compounding overall risk and resulting in risks transmitting through interconnected systems and across regions.

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=== Observed Impacts from Climate Change ===

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'''B.1 Human-induced climate change, including more frequent and intense extreme events, has caused widespread adverse impacts and related losses and damages to nature and people, beyond natural climate variability. Some development and adaptation efforts have reduced vulnerability. Across sectors and regions the most vulnerable people and systems are observed to be disproportionately affected. The rise in weather and climate extremes has led to some irreversible impacts as natural and human systems are pushed beyond their ability to adapt. ( '''''high confidence''''' )   Expand [[#figure-spm-2|Figure SPM.2]] Links to chapters TS B.1, Figure TS.5, 1.3, 2.3, 2.4, 2.6, 3.3, 3.4, 3.5, 4.2, 4.3, 5.2, 5.12, 6.2, 7.2, 8.2, 9.6, 9.8, 9.10, 9.11, 10.4, 11.3, 12.3, 12.4, 13.10, 14.4, 14.5, 15.3, 16.2, CCP1.2, CCP3.2, CCP4.1, CCP6.2, CCP7.2, CCP7.3, CCB DISASTER, CCB EXTREMES, CCB ILLNESS, CCB MIGRATE, CCB NATURAL, CCB SLR'''
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'''B.1.1''' Widespread, pervasive impacts to ecosystems, people, settlements, and infrastructure have resulted from observed increases in the frequency and intensity of climate and weather extremes, including hot extremes on land and in the ocean, heavy precipitation events, drought and fire weather ( ''high confidence'' ). Increasingly since AR5, these observed impacts have been attributed [[#footnote-022|28]] to human-induced climate change particularly through increased frequency and severity of extreme events. These include increased heat-related human mortality ( ''medium confidence'' ), warm-water coral bleaching and mortality ( ''high confidence'' ), and increased drought-related tree mortality ( ''high confidence'' ). Observed increases in areas burned by wildfires have been attributed to human-induced climate change in some regions ( ''medium'' to ''high confidence'' ). Adverse impacts from tropical cyclones, with related losses and damages 19 , have increased due to sea level rise and the increase in heavy precipitation ( ''medium confidence'' ). Impacts in natural and human systems from slow-onset processes [[#footnote-021|29]] such as ocean acidification, sea level rise or regional decreases in precipitation have also been attributed to human induced climate change ( ''high confidence'' ). { 1.3, 2.3, 2.4, 2.5, 3.2, 3.4, 3.5, 3.6, 4.2, 5.2, 5.4, 5.6, 5.12, 7.2, 9.6, 9.7, 9.8, 9.11, 11.3, Box 11.1, Box 11.2, Table 11.9, 12.3, 12.4, 13.3, 13.5, 13.10, 14.2, 14.5, 15.7, 15.8, 16.2, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , Box [https://www.ipcc.ch/chapter/spm#CCP5.1 CCP5.1] , [https://www.ipcc.ch/chapter/spm#CCP7.3 CCP7.3] , CCB DISASTER, CCB EXTREME, CCB ILLNESS, WGI AR6 SPM.3, WGI AR6 9, WGI AR6 11.3–11.8, SROCC Chapter 4 }

'''B.1.2''' Climate change has caused substantial damages, and increasingly irreversible losses, in terrestrial, freshwater and coastal and open ocean marine ecosystems ( ''high confidence'' ). The extent and magnitude of climate change impacts are larger than estimated in previous assessments ( ''high confidence'' ). Widespread deterioration of ecosystem structure and function, resilience and natural adaptive capacity, as well as shifts in seasonal timing have occurred due to climate change ( ''high confidence'' ), with adverse socioeconomic consequences ( ''high confidence'' ). Approximately half of the species assessed globally have shifted polewards or, on land, also to higher elevations ( ''very high confidence'' ). Hundreds of local losses of species have been driven by increases in the magnitude of heat extremes ( ''high confidence'' ), as well as mass mortality events on land and in the ocean ( ''very high confidence'' ) and loss of kelp forests ( ''high confidence'' ). Some losses are already irreversible, such as the first species extinctions driven by climate change ( ''medium confidence'' ). Other impacts are approaching irreversibility such as the impacts of hydrological changes resulting from the retreat of glaciers, or the changes in some mountain ( ''medium confidence'' ) and Arctic ecosystems driven by permafrost thaw ( ''high confidence'' ). (Figure SPM.2a). { TS B.1, Figure TS.5, 2.3, 2.4, 3.4, 3.5, 4.2, 4.3, 4.5, 9.6, 10.4, 11.3, 12.3, 12.8, 13.3, 13.4, 13.10, 14.4, 14.5, 14.6, 15.3, 16.2, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP3.2 CCP3.2] , [https://www.ipcc.ch/chapter/spm#CCP4.1 CCP4.1] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , Figure [https://www.ipcc.ch/chapter/spm#CCP5.4 CCP5.4] , [https://www.ipcc.ch/chapter/spm#CCP6.1 CCP6.1] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP7.2 CCP7.2] , [https://www.ipcc.ch/chapter/spm#CCP7.3 CCP7.3] , CCB EXTREMES, CCB ILLNESS, CCB MOVING PLATE, CCB NATURAL, CCB PALEO, CCB SLR, SROCC 2.3 }

'''B.1.3''' Climate change including increases in frequency and intensity of extremes have reduced food and water security, hindering efforts to meet Sustainable Development Goals ( ''high confidence'' ). Although overall agricultural productivity has increased, climate change has slowed this growth over the past 50 years globally ( ''medium confidence'' ), related negative impacts were mainly in mid- and low latitude regions but positive impacts occurred in some high latitude regions ( ''high confidence'' ). Ocean warming and ocean acidification have adversely affected food production from shellfish aquaculture and fisheries in some oceanic regions ( ''high confidence'' ). Increasing weather and climate extreme events have exposed millions of people to acute food insecurity [[#footnote-020|30]] and reduced water security, with the largest impacts observed in many locations and/or communities in Africa, Asia, Central and South America, Small Islands and the Arctic ( ''high confidence'' ). Jointly, sudden losses of food production and access to food compounded by decreased diet diversity have increased malnutrition in many communities ( ''high confidence'' ), especially for Indigenous Peoples, small-scale food producers and low-income households ( ''high confidence'' ), with children, elderly people and pregnant women particularly impacted ( ''high confidence'' ). Roughly half of the world’s population currently experience severe water scarcity for at least some part of the year due to climatic and non-climatic drivers ( ''medium confidence'' ). (Figure SPM.2b) { 3.5, 4.3, 4.4, Box 4.1, 5.2, 5.4, 5.8, 5.9, 5.12, 7.1, 7.2, 9.8, 10.4, 11.3, 12.3, 13.5, 14.4, 14.5, 15.3, 16.2, [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] }

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[[File:6ff1dfe5ae9a2f83ce384e8351c84558 IPCC_AR6_WGII_Figure_SPM_002.png]]

'''Figure SPM.2 |''' '''Observed global and regional impacts on ecosystems and human systems attributed to climate change.''' Confidence levels reflect uncertainty in attribution of the observed impact to climate change. Global assessments focus on large studies, multi-species, meta-analyses and large reviews. For that reason they can be assessed with higher confidence than regional studies, which may often rely on smaller studies that have more limited data. Regional assessments consider evidence on impacts across an entire region and do not focus on any country in particular.

'''(a)''' Climate change has already altered terrestrial, freshwater and ocean ecosystems at global scale, with multiple impacts evident at regional and local scales where there is sufficient literature to make an assessment. Impacts are evident on ecosystem structure, species geographic ranges and timing of seasonal life cycles (phenology) (for methodology and detailed references to chapters and cross-chapter papers see SMTS.1 and SMTS.1.1).

'''(b)''' Climate change has already had diverse adverse impacts on human systems, including on water security and food production, health and well-being, and cities, settlements and infrastructure. The + and – symbols indicate the direction of observed impacts, with a – denoting an increasing adverse impact and a ± denoting that, within a region or globally, both adverse and positive impacts have been observed (e.g., adverse impacts in one area or food item may occur with positive impacts in another area or food item). Globally, ‘–’ denotes an overall adverse impact; ‘Water scarcity’ considers, e.g., water availability in general, groundwater, water quality, demand for water, drought in cities. Impacts on food production were assessed by excluding non-climatic drivers of production increases; Global assessment for agricultural production is based on the impacts on global aggregated production; ‘Reduced animal and livestock health and productivity’ considers, e.g., heat stress, diseases, productivity, mortality; ‘Reduced fisheries yields and aquaculture production’ includes marine and freshwater fisheries/production; ‘Infectious diseases’ include, e.g., water-borne and vector-borne diseases; ‘Heat, malnutrition and other’ considers, e.g., human heat-related morbidity and mortality, labour productivity, harm from wildfire, nutritional deficiencies; ‘Mental health’ includes impacts from extreme weather events, cumulative events, and vicarious or anticipatory events; ‘Displacement’ assessments refer to evidence of displacement attributable to climate and weather extremes; ‘Inland flooding and associated damages’ considers, e.g., river overflows, heavy rain, glacier outbursts, urban flooding; ‘Flood/storm induced damages in coastal areas’ include damages due to, e.g., cyclones, sea level rise, storm surges. Damages by key economic sectors are observed impacts related to an attributable mean or extreme climate hazard or directly attributed. Key economic sectors include standard classifications and sectors of importance to regions (for methodology and detailed references to chapters and cross-chapter papers see SMTS.1 and SMTS.1.2).

'''B.1.4''' Climate change has adversely affected physical health of people globally ( ''very high confidence)'' and mental health of people in the assessed regions ( ''very high confidence'' ). Climate change impacts on health are mediated through natural and human systems, including economic and social conditions and disruptions ( ''high confidence'' ). In all regions extreme heat events have resulted in human mortality and morbidity ( ''very high confidence'' ). The occurrence of climate-related food-borne and water-borne diseases has increased ( ''very high confidence'' ). The incidence of vector-borne diseases has increased from range expansion and/or increased reproduction of disease vectors ( ''high confidence'' ). Animal and human diseases, including zoonoses, are emerging in new areas ( ''high confidence'' ). Water and food-borne disease risks have increased regionally from climate-sensitive aquatic pathogens, including ''Vibrio'' spp. ( ''high confidence'' ), and from toxic substances from harmful freshwater cyanobacteria ( ''medium confidence'' ). Although diarrheal diseases have decreased globally, higher temperatures, increased rain and flooding have increased the occurrence of diarrheal diseases, including cholera ( ''very high confidence'' ) and other gastrointestinal infections ( ''high confidence'' ). In assessed regions, some mental health challenges are associated with increasing temperatures ( ''high confidence'' ), trauma from weather and climate extreme events ( ''very high confidence'' ), and loss of livelihoods and culture ( ''high confidence'' ). Increased exposure to wildfire smoke, atmospheric dust, and aeroallergens have been associated with climate-sensitive cardiovascular and respiratory distress ( ''high confidence'' ). Health services have been disrupted by extreme events such as floods ( ''high confidence'' ). { 4.3, 5.12, 7.2, Box 7.3, 8.2, 8.3, Box 8.6, Figure 8.10, 9.10, Figure 9.33, Figure 9.34, 10.4, 11.3, 12.3, 13.7, 14.4, 14.5, Figure 14.8, 15.3, 16.2, [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , Table [https://www.ipcc.ch/chapter/spm#CCP5.1 CCP5.1] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , Figure [https://www.ipcc.ch/chapter/spm#CCP6.3 CCP6.3] , Table CCB ILLNESS.1 }

'''B.1.5''' In urban settings, observed climate change has caused impacts on human health, livelihoods and key infrastructure ( ''high confidence'' ). Multiple climate and non-climate hazards impact cities, settlements and infrastructure and sometimes coincide, magnifying damage ( ''high confidence'' ). Hot extremes including heatwaves have intensified in cities ( ''high'' ''confidence'' ), where they have also aggravated air pollution events ( ''medium confidence'' ) and limited functioning of key infrastructure ( ''high confidence'' ). Observed impacts are concentrated amongst the economically and socially marginalized urban residents, e.g., in informal settlements ( ''high confidence'' ) ''.'' Infrastructure, including transportation, water, sanitation and energy systems have been compromised by extreme and slow-onset events, with resulting economic losses, disruptions of services and impacts to well-being ( ''high confidence'' ). { 4.3, 6.2, 7.1, 7.2, 9.9, 10.4, 11.3, 12.3, 13.6, 14.5, 15.3, [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP4.2 CCP4.2] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] }

'''B.1.6''' Overall adverse economic impacts attributable to climate change, including slow-onset and extreme weather events, have been increasingly identified ( ''medium confidence'' ). Some positive economic effects have been identified in regions that have benefited from lower energy demand as well as comparative advantages in agricultural markets and tourism ( ''high confidence'' ). Economic damages from climate change have been detected in climate-exposed sectors, with regional effects to agriculture, forestry, fishery, energy, and tourism ( ''high confidence'' ), and through outdoor labour productivity ( ''high confidence'' ). Some extreme weather events, such as tropical cyclones, have reduced economic growth in the short-term ( ''high confidence'' ). Non-climatic factors including some patterns of settlement, and siting of infrastructure have contributed to the exposure of more assets to extreme climate hazards increasing the magnitude of the losses ( ''high confidence'' ). Individual livelihoods have been affected through changes in agricultural productivity, impacts on human health and food security, destruction of homes and infrastructure, and loss of property and income, with adverse effects on gender and social equity ( ''high confidence'' ). { 3.5, 4.2, 5.12, 6.2, 7.2, 8.2, 9.6, 10.4, 13.10, 14.5, Box 14.6, 16.2, Table 16.5, 18.3, [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , CCB GENDER, CWGB ECONOMICS }

'''B.1.7''' Climate change is contributing to humanitarian crises where climate hazards interact with high vulnerability ( ''high confidence'' ). Climate and weather extremes are increasingly driving displacement in all regions ( ''high confidence'' ), with Small Island States disproportionately affected ( ''high confidence'' ). Flood and drought-related acute food insecurity and malnutrition have increased in Africa ( ''high confidence'' ) and Central and South America ( ''high confidence'' ). While non-climatic factors are the dominant drivers of existing intrastate violent conflicts, in some assessed regions extreme weather and climate events have had a small, adverse impact on their length, severity or frequency, but the statistical association is weak ( ''medium confidence'' ). Through displacement and involuntary migration from extreme weather and climate events, climate change has generated and perpetuated vulnerability ( ''medium confidence'' ). { 4.2, 4.3, 5.4, 7.2, 9.8, Box 9.9, Box 10.4, 12.3, 12.5, 16.2, CCB DISASTER, CCB MIGRATE }

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=== Vulnerability and Exposure of Ecosystems and People ===

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'''B.2 Vulnerability of ecosystems and people to climate change differs substantially among and within regions ( '''''very high confidence''''' , driven by patterns of intersecting socioeconomic development, unsustainable ocean and land use, inequity, marginalization, historical and ongoing patterns of inequity such as colonialism, and governance [[#footnote-019|31]] ( '''''high confidence''''' ). Approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change ( '''''high confidence''''' ). A high proportion of species is vulnerable to climate change ( '''''high confidence''''' ). Human and ecosystem vulnerability are interdependent ( '''''high confidence''''' ). Current unsustainable development patterns are increasing exposure of ecosystems and people to climate hazards ( '''''high confidence''''' ).   Expand Links to chapters 2.3, 2.4, 3.5, 4.3, 6.2, 8.2, 8.3, 9.4, 9.7, 10.4, 12.3, 14.5, 15.3, CCP5.2, CCP6.2, CCP7.3, CCP7.4, CCB GENDER'''
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'''B.2.1''' Since AR5 there is increasing evidence that degradation and destruction of ecosystems by humans increases the vulnerability of people ( ''high confidence'' ). Unsustainable land-use and land cover change, unsustainable use of natural resources, deforestation, loss of biodiversity, pollution, and their interactions, adversely affect the capacities of ecosystems, societies, communities and individuals to adapt to climate change ( ''high confidence'' ). Loss of ecosystems and their services has cascading and long-term impacts on people globally, especially for Indigenous Peoples and local communities who are directly dependent on ecosystems, to meet basic needs ( ''high confidence'' ). { 2.3, 2.5, 2.6, 3.5, 3.6, 4.2, 4.3, 4.6, 5.1, 5.4, 5.5, 5.7, 5.8, 7.2, 8.1, 8.2, 8.3, 8.4, 8.5, 9.6, 10.4, 11.3, 12.2, 12.5, 13.8, 14.4, 14.5, 15.3, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP1.3 CCP1.3] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , CCP3, [https://www.ipcc.ch/chapter/spm#CCP4.3 CCP4.3] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP7.2 CCP7.2] , [https://www.ipcc.ch/chapter/spm#CCP7.3 CCP7.3] , [https://www.ipcc.ch/chapter/spm#CCP7.4 CCP7.4] , CCB ILLNESS, CCB MOVING PLATE, CCB SLR }

'''B.2.2''' Non-climatic human-induced factors exacerbate current ecosystem vulnerability to climate change ( ''very high confidence'' ). Globally, and even within protected areas, unsustainable use of natural resources, habitat fragmentation, and ecosystem damage by pollutants increase ecosystem vulnerability to climate change ( ''high confidence'' ). Globally, less than 15% of the land, 21% of the freshwater and 8% of the ocean are protected areas. In most protected areas, there is insufficient stewardship to contribute to reducing damage from, or increasing resilience to, climate change ( ''high confidence'' ). { 2.4, 2.5, 2.6, 3.4, 3.6, 4.2, 4.3, 5.8, 9.6, 11.3, 12.3, 13.3, 13.4, 14.5, 15.3, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , Figure [https://www.ipcc.ch/chapter/spm#CCP1.1 CCP1.1] 5, [https://www.ipcc.ch/chapter/spm#CCP2.1 CCP2.1] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP4.2 CCP4.2] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP7.2 CCP7.2] , [https://www.ipcc.ch/chapter/spm#CCP7.3 CCP7.3] , CCB NATURAL }

'''B.2.3''' Future vulnerability of ecosystems to climate change will be strongly influenced by the past, present and future development of human society, including from overall unsustainable consumption and production, and increasing demographic pressures, as well as persistent unsustainable use and management of land, ocean, and water ( ''high confidence'' ). Projected climate change, combined with non-climatic drivers, will cause loss and degradation of much of the world’s forests ( ''high confidence'' ), coral reefs and low-lying coastal wetlands ( ''very high confidence'' ). While agricultural development contributes to food security, unsustainable agricultural expansion, driven in part by unbalanced diets [[#footnote-018|32]] , increases ecosystem and human vulnerability and leads to competition for land and/or water resources ( ''high confidence'' ). { 2.2, 2.3, 2.4, 2.6, 3.4, 3.5, 3.6, 4.3, 4.5, 5.6, 5.12, 5.13, 7.2, 12.3, 13.3, 13.4, 13.10, 14.5, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP7.2 CCP7.2] , [https://www.ipcc.ch/chapter/spm#CCP7.3 CCP7.3] , CCB HEALTH, CCB NATURAL }

'''B.2.4''' Regions and people with considerable development constraints have high vulnerability to climatic hazards ( ''high confidence'' ). Global hotspots of high human vulnerability are found particularly in West-, Central- and East Africa, South Asia, Central and South America, Small Island Developing States and the Arctic ( ''high confidence'' ). Vulnerability is higher in locations with poverty, governance challenges and limited access to basic services and resources, violent conflict and high levels of climate-sensitive livelihoods (e.g., smallholder farmers, pastoralists, fishing communities) ( ''high confidence'' ). Between 2010–2020, human mortality from floods, droughts and storms was 15 times higher in highly vulnerable regions, compared to regions with very low vulnerability ( ''high confidence'' ). Vulnerability at different spatial levels is exacerbated by inequity and marginalization linked to gender, ethnicity, low income or combinations thereof ( ''high confidence'' ), especially for many Indigenous Peoples and local communities ( ''high confidence'' ). Present development challenges causing high vulnerability are influenced by historical and ongoing patterns of inequity such as colonialism, especially for many Indigenous Peoples and local communities ( ''high confidence'' ). { 4.2, 5.12, 6.2, 6.4, 7.1, 7.2, Box 7.1, 8.2, 8.3, Box 8.4, Figure 8.6, Box 9.1, 9.4, 9.7, 9.9, 10.3, 10.4, 10.6, 12.3, 12.5, Box 13.2, 14.4, 15.3, 15.6, 16.2, [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP7.4 CCP7.4] }

'''B.2.5''' Future human vulnerability will continue to concentrate where the capacities of local, municipal and national governments, communities and the private sector are least able to provide infrastructures and basic services ( ''high confidence'' ). Under the global trend of urbanization, human vulnerability will also concentrate in informal settlements and rapidly growing smaller settlements ( ''high confidence'' ). In rural areas vulnerability will be heightened by compounding processes including high emigration, reduced habitability and high reliance on climate-sensitive livelihoods ( ''high confidence'' ). Key infrastructure systems including sanitation, water, health, transport, communications and energy will be increasingly vulnerable if design standards do not account for changing climate conditions ( ''high confidence'' ). Vulnerability will also rapidly rise in low-lying Small Island Developing States and atolls in the context of sea level rise and in some mountain regions, already characterised by high vulnerability due to high dependence on climate-sensitive livelihoods, rising population displacement, the accelerating loss of ecosystem services and limited adaptive capacities ( ''high confidence'' ). Future exposure to climatic hazards is also increasing globally due to socioeconomic development trends including migration, growing inequality and urbanization ''(high confidence'' ). { 4.5, 5.5, 6.2, 7.2, 8.3, 9.9, 9.11, 10.3, 10.4, 12.3, 12.5, 13.6, 14.5, 15.3, 15.4, 16.5, [https://www.ipcc.ch/chapter/spm#CCP2.3 CCP2.3] , [https://www.ipcc.ch/chapter/spm#CCP4.3 CCP4.3] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP5.4 CCP5.4] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , CCB MIGRATE }

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=== Risks in the near term (2021–2040) ===

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'''B.3 Global warming, reaching 1.5°C in the near-term, would cause unavoidable increases in multiple climate hazards and present multiple risks to ecosystems and humans ( '''''very high confidence''''' ). The level of risk will depend on concurrent near-term trends in vulnerability, exposure, level of socioeconomic development and adaptation ( '''''high confidence''''' ). Near-term actions that limit global warming to close to 1.5°C would substantially reduce projected losses and damages related to climate change in human systems and ecosystems, compared to higher warming levels, but cannot eliminate them all ( '''''very high confidence''''' )   Expand [[#figure-spm-3|Figure SPM.3]] [[#box-spm-1|Box SPM.1]] Links to chapters 16.4, 16.5, 16.6, CCP1.2, CCP5.3, CCB SLR, WGI AR6 SPM B1.3, WGI AR6 Table SPM.1'''
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'''B.3.1''' Near-term warming and increased frequency, severity and duration of extreme events will place many terrestrial, freshwater, coastal and marine ecosystems at high or very high risks of biodiversity loss ( ''medium to very high confidence'' , depending on ecosystem). Near-term risks for biodiversity loss are moderate to high in forest ecosystems ( ''medium confidence'' ), kelp and seagrass ecosystems ( ''high'' to ''very high confidence'' ), and high to very high in Arctic sea-ice and terrestrial ecosystems ( ''high confidence'' ) and warm-water coral reefs ( ''very high confidence'' ). Continued and accelerating sea level rise will encroach on coastal settlements and infrastructure ( ''high confidence'' ) and commit low-lying coastal ecosystems to submergence and loss ( ''medium confidence'' ). If trends in urbanisation in exposed areas continue, this will exacerbate the impacts, with more challenges where energy, water and other services are constrained ( ''medium confidence'' ). The number of people at risk from climate change and associated loss of biodiversity will progressively increase ( ''medium confidence'' ). Violent conflict and, separately, migration patterns, in the near-term will be driven by socioeconomic conditions and governance more than by climate change ( ''medium confidence'' ). (Figure SPM.3) { 2.5, 3.4, 4.6, 6.2, 7.3, 8.7, 9.2, 9.9, 11.6, 12.5, 13.6, 13.10, 14.6, 15.3, 16.5, 16.6, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP2.1 CCP2.1] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP6.3 CCP6.3] , CCB MIGRATE, CCB SLR }

'''B.3.2''' In the near term, climate-associated risks to natural and human systems depend more strongly on changes in their vulnerability and exposure than on differences in climate hazards between emissions scenarios ( ''high confidence'' ). Regional differences exist, and risks are highest where species and people exist close to their upper thermal limits, along coastlines, in close association with ice or seasonal rivers ( ''high confidence'' ). Risks are also high where multiple non-climate drivers persist or where vulnerability is otherwise elevated ( ''high confidence'' ). Many of these risks are unavoidable in the near-term, irrespective of emissions scenario ( ''high confidence'' ). Several risks can be moderated with adaptation ( ''high confidence'' ). (Figure SPM.3, Section C) { 2.5, 3.3, 3.4, 4.5, 6.2, 7.1, 7.3, 8.2, 11.6, 12.4, 13.6, 13.7, 13.10, 14.5, 16.4, 16.5, [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP4.3 CCP4.3] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , CCB SLR, WGI AR6 Table SPM.1 }

'''B.3.3''' Levels of risk for all Reasons for Concern (RFC) are assessed to become high to very high at lower global warming levels than in AR5 ( ''high confidence'' ). Between 1.2°C and 4.5°C global warming level very high risks emerge in all five RFCs compared to just two RFCs in AR5 ( ''high confidence'' ). Two of these transitions from high to very high risk are associated with near-term warming: risks to unique and threatened systems at a median value of 1.5 [1.2 to 2.0] °C ( ''high confidence'' ) and risks associated with extreme weather events at a median value of 2.0 [1.8 to 2.5] °C ( ''medium confidence'' ). Some key risks contributing to the RFCs are projected to lead to widespread, pervasive, and potentially irreversible impacts at global warming levels of 1.5–2°C if exposure and vulnerability are high and adaptation is low ( ''medium confidence'' ). Near-term actions that limit global warming to close to 1.5°C would substantially reduce projected losses and damages related to climate change in human systems and ecosystems, compared to higher warming levels, but cannot eliminate them all ( ''very high confidence'' ). (Figure SPM.3b) { 16.5, 16.6, CCB SLR }

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=== Mid to Long-term Risks (2041–2100) ===

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'''B.4 Beyond 2040 and depending on the level of global warming, climate change will lead to numerous risks to natural and human systems ( '''''high confidence''''' ). For 127 identified key risks, assessed mid- and long-term impacts are up to multiple times higher than currently observed ( '''''high confidence''''' ). The magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related losses and damages escalate with every increment of global warming ( '''''very high confidence''''' ).   Expand [[#figure-spm-3|Figure SPM.3]] Links to chapters 2.5, 3.4, 4.4, 5.2, 6.2, 7.3, 8.4, 9.2, 10.2, 11.6, 12.4, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 14.6, 15.3, 16.5, 16.6, CCP2.2, CCP3.3, CCP4.3, CCP5.3, CCP6.4, CCP7.3'''
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'''B.4.1''' Biodiversity loss and degradation, damages to and transformation of ecosystems are already key risks for every region due to past global warming and will continue to escalate with every increment of global warming ( ''very high confidence'' ). In terrestrial ecosystems, 3 to 14% of species assessed [[#footnote-017|33]] will ''likely'' face very high risk of extinction [[#footnote-016|34]] at global warming levels of 1.5°C, increasing up to 3 to 18% at 2°C, 3 to 29% at 3°C, 3 to 39% at 4°C, and 3 to 48% at 5°C. In ocean and coastal ecosystems, risk of biodiversity loss ranges between moderate and very high by 1.5°C global warming level and is moderate to very high by 2°C but with more ecosystems at high and very high risk ( ''high confidence'' ), and increases to high to very high across most ocean and coastal ecosystems by 3°C ( ''medium'' to ''high confidence'' , depending on ecosystem). Very high extinction risk for endemic species in biodiversity hotspots is projected to at least double from 2% between 1.5°C and 2°C global warming levels and to increase at least tenfold if warming rises from 1.5°C to 3°C ( ''medium confidence'' ). (Figure SPM.3c, d, f) { 2.4, 2.5, 3.4, 3.5, 12.3, 12.5, Table 12.6, 13.4, 13.10, 16.4, 16.6, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , Figure CCP1.6, Figure CCP1.7, [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP6.3 CCP6.3] , CCB PALEO }

'''B.4.2''' Risks in physical water availability and water-related hazards will continue to increase by the mid- to long-term in all assessed regions, with greater risk at higher global warming levels ( ''high confidence'' ). At approximately 2°C global warming, snowmelt water availability for irrigation is projected to decline in some snowmelt dependent river basins by up to 20%, and global glacier mass loss of 18 ± 13% is projected to diminish water availability for agriculture, hydropower, and human settlements in the mid- to long-term, with these changes projected to double with 4°C global warming ( ''medium confidence'' ). In Small Islands, groundwater availability is threatened by climate change ( ''high confidence'' ). Changes to streamflow magnitude, timing and associated extremes are projected to adversely impact freshwater ecosystems in many watersheds by the mid- to long-term across all assessed scenarios ( ''medium confidence'' ). Projected increases in direct flood damages are higher by 1.4 to 2 times at 2°C and 2.5 to 3.9 times at 3°C compared to 1.5°C global warming without adaptation ( ''medium confidence'' ). At global warming of 4°C, approximately 10% of the global land area is projected to face increases in both extreme high and low river flows in the same location, with implications for planning for all water use sectors ( ''medium confidence'' ). Challenges for water management will be exacerbated in the near, mid and long term, depending on the magnitude, rate and regional details of future climate change and will be particularly challenging for regions with constrained resources for water management ( ''high confidence'' ). { 2.3, 4.4, 4.5, Box 4.2, Figure 4.20, 15.3, [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , CCB DISASTER, SROCC 2.3 }

'''B.4.3''' Climate change will increasingly put pressure on food production and access, especially in vulnerable regions, undermining food security and nutrition ( ''high confidence'' ). Increases in frequency, intensity and severity of droughts, floods and heatwaves, and continued sea level rise will increase risks to food security ( ''high confidence'' ) in vulnerable regions from moderate to high between 1.5°C and 2°C global warming level, with no or low levels of adaptation ( ''medium confidence'' ). At 2°C or higher global warming level in the mid-term, food security risks due to climate change will be more severe, leading to malnutrition and micro-nutrient deficiencies, concentrated in Sub-Saharan Africa, South Asia, Central and South America and Small Islands ( ''high confidence).'' Global warming will progressively weaken soil health and ecosystem services such as pollination, increase pressure from pests and diseases, and reduce marine animal biomass, undermining food productivity in many regions on land and in the ocean ( ''medium confidence'' ). At 3°C or higher global warming level in the long term, areas exposed to climate-related hazards will expand substantially compared with 2°C or lower global warming level ( ''high confidence'' ), exacerbating regional disparity in food security risks ( ''high confidence'' ). (Figure SPM.3) { 1.1, 3.3, 4.5, 5.2, 5.4, 5.5, 5.8, 5.9, 5.12, 7.3, 8.3, 9.11, 13.5, 15.3, 16.5, 16.6, CCB MOVING PLATE, CCB SLR }

<div id="figure-spm-3" class="Figure"></div>

[[File:508f10da72747d8cd70350ceb58158e0 IPCC_AR6_WGII_Figure_SPM_003a.png]]

'''Figure SPM.3 |''' '''Synthetic diagrams of global and sectoral''' '''assessments and examples of regional key risks.''' Diagrams show the change in the levels of impacts and risks assessed for global warming of 0–5°C global surface temperature change relative to pre-industrial period (1850–1900) over the range.

'''(a)''' Global surface temperature changes in °C relative to 1850–1900. These changes were obtained by combining CMIP6 model simulations with observational constraints based on past simulated warming, as well as an updated assessment of equilibrium climate sensitivity (Box SPM.1). Changes relative to 1850–1900 based on 20-year averaging periods are calculated by adding 0.85°C (the observed global surface temperature increase from 1850–1900 to 1995–2014) to simulated changes relative to 1995–2014. ''Very likely'' ranges are shown for SSP1-2.6 and SSP3-7.0 (WGI AR6 Figure SPM.8). Assessments were carried out at the global scale for (b), (c), (d) and (e).

'''(b)''' The Reasons for Concern (RFC) framework communicates scientific understanding about accrual of risk for five broad categories. Diagrams are shown for each RFC, assuming low to no adaptation (i.e., adaptation is fragmented, localized and comprises incremental adjustments to existing practices). However, the transition to a very high risk level has an emphasis on irreversibility and adaptation limits. Undetectable risk level (white) indicates no associated impacts are detectable and attributable to climate change; moderate risk (yellow) indicates associated impacts are both detectable and attributable to climate change with at least ''medium confidence'' , also accounting for the other specific criteria for key risks; high risk (red) indicates severe and widespread impacts that are judged to be high on one or more criteria for assessing key risks; and very high risk level (purple) indicates very high risk of severe impacts and the presence of significant irreversibility or the persistence of climate-related hazards, combined with limited ability to adapt due to the nature of the hazard or impacts/risks. The horizontal line denotes the present global warming of 1.09°C which is used to separate the observed, past impacts below the line from the future projected risks above it. RFC1: Unique and threatened systems: ecological and human systems that have restricted geographic ranges constrained by climate-related conditions and have high endemism or other distinctive properties. Examples include coral reefs, the Arctic and its Indigenous Peoples, mountain glaciers and biodiversity hotspots. RFC2: Extreme weather events: risks/impacts to human health, livelihoods, assets and ecosystems from extreme weather events such as heatwaves, heavy rain, drought and associated wildfires, and coastal flooding. RFC3: Distribution of impacts: risks/impacts that disproportionately affect particular groups due to uneven distribution of physical climate change hazards, exposure or vulnerability. RFC4: Global aggregate impacts: impacts to socio-ecological systems that can be aggregated globally into a single metric, such as monetary damages, lives affected, species lost or ecosystem degradation at a global scale. RFC5: Large-scale singular events: relatively large, abrupt and sometimes irreversible changes in systems caused by global warming, such as ice sheet disintegration or thermohaline circulation slowing. Assessment methods are described in SM16.6 and are identical to AR5, but are enhanced by a structured approach to improve robustness and facilitate comparison between AR5 and AR6.

Risks for '''(c)''' terrestrial and freshwater ecosystems and '''(d)''' ocean ecosystems. For c) and d), diagrams shown for each risk assume low to no adaptation. The transition to a very high risk level has an emphasis on irreversibility and adaptation limits.

'''(e)''' Climate-sensitive human health outcomes under three scenarios of adaptation effectiveness. The assessed projections were based on a range of scenarios, including SRES, CMIP5, and ISIMIP, and, in some cases, demographic trends. The diagrams are truncated at the nearest whole ºC within the range of temperature change in 2100 under three SSP scenarios in panel (a).

'''(f)''' Examples of regional key risks. Risks identified are of at least ''medium confidence'' level. Key risks are identified based on the magnitude of adverse consequences (pervasiveness of the consequences, degree of change, irreversibility of consequences, potential for impact thresholds or tipping points, potential for cascading effects beyond system boundaries); likelihood of adverse consequences; temporal characteristics of the risk; and ability to respond to the risk, e.g., by adaptation. The full set of 127 assessed global and regional key risks is given in SM16.7. Diagrams are provided for some risks. The development of synthetic diagrams for Small Islands, Asia and Central and South America were limited by the availability of adequately downscaled climate projections, with uncertainty in the direction of change, the diversity of climatologies and socioeconomic contexts across countries within a region, and the resulting low number of impact and risk projections for different warming levels. Absence of risks diagrams does not imply absence of risks within a region. (Box SPM.1) { Figure TS.4, Figure 2.11, Figure SM3.1, Figure 7.9, Figure 9.6, Figure 11.6, Figure 13.28, 16.5, 16.6, Figure 16.15, SM16.3, SM16.4, SM16.5, SM16.6 (methodologies), SM16.7, Figure CCP4.8, Figure [https://www.ipcc.ch/chapter/spm#CCP4.1 CCP4.1] 0, Figure [https://www.ipcc.ch/chapter/spm#CCP6.5 CCP6.5] , WGI AR6 2, WGI AR6 SPM A.1.2, WGI AR6 Figure SPM.8 }

'''B.4.4''' Climate change and related extreme events will significantly increase ill health and premature deaths from the near- to long-term ( ''high confidence'' ). Globally, population exposure to heatwaves will continue to increase with additional warming, with strong geographical differences in heat-related mortality without additional adaptation ( ''very high confidence'' ) ''.'' Climate-sensitive food-borne, water-borne, and vector-borne disease risks are projected to increase under all levels of warming without additional adaptation ( ''high confidence'' ). In particular, dengue risk will increase with longer seasons and a wider geographic distribution in Asia, Europe, Central and South America and sub-Saharan Africa, potentially putting additional billions of people at risk by the end of the century ( ''high confidence'' ) ''.'' Mental health challenges, including anxiety and stress, are expected to increase under further global warming in all assessed regions, particularly for children, adolescents, elderly, and those with underlying health conditions ( ''very high confidence'' ). { 4.5, 5.12, Box 5.10, 7.3, Figure 7.9, 8.4, 9.10, Figure 9.32, Figure 9.35, 10.4, Figure 10.11, 11.3, 12.3, Figure 12.5, Figure 12.6, 13.7, Figure 13.23, Figure 13.24, 14.5, 15.3, [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] }

'''B.4.5''' Climate change risks to cities, settlements and key infrastructure will rise rapidly in the mid- and long-term with further global warming, especially in places already exposed to high temperatures, along coastlines, or with high vulnerabilities ( ''high confidence'' ). Globally, population change in low-lying cities and settlements will lead to approximately a billion people projected to be at risk from coastal-specific climate hazards in the mid-term under all scenarios, including in Small Islands ( ''high confidence'' ). The population potentially exposed to a 100-year coastal flood is projected to increase by about 20% if global mean sea level rises by 0.15 m relative to 2020 levels; this exposed population doubles at a 0.75 m rise in mean sea level and triples at 1.4 m without population change and additional adaptation ( ''medium confidence'' ). Sea level rise poses an existential threat for some Small Islands and some low-lying coasts ( ''medium confidence'' ). By 2100 the value of global assets within the future 1-in-100 year coastal floodplains is projected to be between US$7.9 and US$12.7 trillion (2011 value) under RCP4.5, rising to between US$8.8 and US$14.2 trillion under RCP8.5 ( ''medium confidence'' ). Costs for maintenance and reconstruction of urban infrastructure, including building, transportation, and energy will increase with global warming level ( ''medium confidence'' ), the associated functional disruptions are projected to be substantial particularly for cities, settlements and infrastructure located on permafrost in cold regions and on coasts ( ''high confidence'' ). { 6.2, 9.9, 10.4, 13.6, 13.10, 15.3, 16.5, [https://www.ipcc.ch/chapter/spm#CCP2.1 CCP2.1] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , CCB SLR, SROCC 2.3, SROCC CCB9 }

'''B.4.6''' Projected estimates of global aggregate net economic damages generally increase non-linearly with global warming levels ( ''high confidence'' ). [[#footnote-015|35]] The wide range of global estimates, and the lack of comparability between methodologies, does not allow for identification of a robust range of estimates ( ''high confidence'' ). The existence of higher estimates than assessed in AR5 indicates that global aggregate economic impacts could be higher than previous estimates ( ''low confidence'' ). [[#footnote-014|36]] Significant regional variation in aggregate economic damages from climate change is projected ( ''high confidence'' ) with estimated economic damages per capita for developing countries often higher as a fraction of income ( ''high confidence'' ). Economic damages, including both those represented and those not represented in economic markets, are projected to be lower at 1.5°C than at 3°C or higher global warming levels ( ''high confidence'' ). { 4.4, 9.11, 11.5, 13.10, Box 14.6, 16.5, CWGB ECONOMIC }

'''B.4.7''' In the mid- to long-term, displacement will increase with intensification of heavy precipitation and associated flooding, tropical cyclones, drought and, increasingly, sea level rise ( ''high confidence'' ). At progressive levels of warming, involuntary migration from regions with high exposure and low adaptive capacity would occur ( ''medium confidence'' ). Compared to other socioeconomic factors the influence of climate on conflict is assessed as relatively weak ( ''high confidence'' ). Along long-term socioeconomic pathways that reduce non-climatic drivers, risk of violent conflict would decline ( ''medium confidence'' ). At higher global warming levels, impacts of weather and climate extremes, particularly drought, by increasing vulnerability will increasingly affect violent intrastate conflict ( ''medium confidence'' ). { TS B.7.4, 7.3, 16.5, CCB MIGRATE }

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<span id="complex-compound-and-cascading-risks"></span>
=== Complex, Compound and Cascading Risks ===

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'''B.5 Climate change impacts and risks are becoming increasingly complex and more difficult to manage. Multiple climate hazards will occur simultaneously, and multiple climatic and non-climatic risks will interact, resulting in compounding overall risk and risks cascading across sectors and regions. Some responses to climate change result in new impacts and risks. ( '''''high confidence''''' )   Expand Links to chapters 1.3, 2.4, Box 2.2, Box 9.5, 11.5, 13.5, 14.6, Box 15.1, CCP1.2, CCP2.2, CCB COVID, CCB DISASTER, CCB INTEREG, CCB SRM'''
<div id="spmbulletcont-b5" class="spmbulletcont"></div>

'''B.5.1''' Concurrent and repeated climate hazards occur in all regions, increasing impacts and risks to health, ecosystems, infrastructure, livelihoods and food ( ''high confidence'' ). Multiple risks interact, generating new sources of vulnerability to climate hazards, and compounding overall risk ( ''high confidence'' ). Increasing concurrence of heat and drought events are causing crop production losses and tree mortality ( ''high confidence'' ). Above 1.5°C global warming increasing concurrent climate extremes will increase risk of simultaneous crop losses of maize in major food-producing regions, with this risk increasing further with higher global warming levels ( ''medium confidence'' ). Future sea level rise combined with storm surge and heavy rainfall will increase compound flood risks ( ''high confidence'' ). Risks to health and food production will be made more severe from the interaction of sudden food production losses from heat and drought, exacerbated by heat-induced labour productivity losses ( ''high confidence'' ). These interacting impacts will increase food prices, reduce household incomes, and lead to health risks of malnutrition and climate-related mortality with no or low levels of adaptation, especially in tropical regions ( ''high confidence'' ). Risks to food safety from climate change will further compound the risks to health by increasing food contamination of crops from mycotoxins and contamination of seafood from harmful algal blooms, mycotoxins, and chemical contaminants ( ''high confidence'' ). { Figure TS.10c, 5.2, 5.4, 5.8, 5.9, 5.11, 5.12, 7.2, 7.3, 9.8, 9.11, 10.4, 11.3, 11.5, 12.3, 13.5, 14.5, 15.3, Box 15.1, 16.6, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , , WGI AR6 SPM A.3.1, WGI AR6 SPM A.3.2, WGI AR6 SPM C.2.7 }

'''B.5.2''' Adverse impacts from climate hazards and resulting risks are cascading across sectors and regions ( ''high confidence'' ), propagating impacts along coasts and urban centres ( ''medium confidence'' ) and in mountain regions ( ''high confidence'' ). These hazards and cascading risks also trigger tipping points in sensitive ecosystems and in significantly and rapidly changing social-ecological systems impacted by ice melt, permafrost thaw and changing hydrology in polar regions ( ''high confidence'' ). Wildfires, in many regions, have affected ecosystems and species, people and their built assets, economic activity, and health ( ''medium to high confidence'' ) '''.''' In cities and settlements, climate impacts to key infrastructure are leading to losses and damages across water and food systems, and affect economic activity, with impacts extending beyond the area directly impacted by the climate hazard ( ''high confidence'' ). In Amazonia, and in some mountain regions, cascading impacts from climatic (e.g., heat) and non-climatic stressors (e.g., land use change) will result in irreversible and severe losses of ecosystem services and biodiversity at 2°C global warming level and beyond ( ''medium confidence'' ). Unavoidable sea level rise will bring cascading and compounding impacts resulting in losses of coastal ecosystems and ecosystem services, groundwater salinisation, flooding and damages to coastal infrastructure that cascade into risks to livelihoods, settlements, health, well-being, food and water security, and cultural values in the near to long-term ( ''high confidence'' ). (Figure SPM.3) { Figure TS.10, 2.5, 3.4, 3.5, Box 7.3, Box 8.7, Box 9.4, 11.5, Box 11.1, 12.3, 13.9, 14.6, 15.3, 16.5, 16.6, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP5.2 CCP5.2] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , [https://www.ipcc.ch/chapter/spm#CCP6.3 CCP6.3] , Box [https://www.ipcc.ch/chapter/spm#CCP6.1 CCP6.1] , Box [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , CCB EXTREMES, WGI AR6 Figure SPM.8d }

'''B.5.3''' Weather and climate extremes are causing economic and societal impacts across national boundaries through supply-chains, markets, and natural resource flows, with increasing transboundary risks projected across the water, energy and food sectors ( ''high confidence'' ). Supply chains that rely on specialized commodities and key infrastructure can be disrupted by weather and climate extreme events. Climate change causes the redistribution of marine fish stocks, increasing risk of transboundary management conflicts among fisheries users, and negatively affecting equitable distribution of food provisioning services as fish stocks shift from lower to higher latitude regions, thereby increasing the need for climate-informed transboundary management and cooperation ( ''high confidence'' ). Precipitation and water availability changes increases the risk of planned infrastructure projects, such as hydropower in some regions, having reduced productivity for food and energy sectors including across countries that share river basins ( ''medium confidence'' ). { Figure TS.10e-f, 3.4, 3.5, 4.5, 5.8, 5.13, 6.2, 9.4, Box 9.5,14.5, Box 14.5, Box 14.6, [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , CCB DISASTER, CCB EXTREMES, CCB INTEREG, CCB MOVING PLATE }

'''B.5.4''' Risks arise from some responses that are intended to reduce the risks of climate change, including risks from maladaptation and adverse side effects of some emissions reduction and carbon dioxide removal measures ( ''high confidence'' ). Deployment of afforestation of naturally unforested land, or poorly implemented bioenergy, with or without carbon capture and storage, can compound climate-related risks to biodiversity, water and food security, and livelihoods, especially if implemented at large scales, especially in regions with insecure land tenure ( ''high confidence'' ). { Box 2.2, 4.1, 4.7, 5.13, Table 5.18, Box 9.3, Box 13.2, CCB NATURAL, CWGB BIOECONOMY }

'''B.5.5''' Solar radiation modification approaches, if they were to be implemented, introduce a widespread range of new risks to people and ecosystems, which are not well understood ( ''high confidence'' ). Solar radiation modification approaches have potential to offset warming and ameliorate some climate hazards, but substantial residual climate change or overcompensating change would occur at regional scales and seasonal timescales ( ''high confidence'' ). Large uncertainties and knowledge gaps are associated with the potential of solar radiation modification approaches to reduce climate change risks. Solar radiation modification would not stop atmospheric CO 2 concentrations from increasing or reduce resulting ocean acidification under continued anthropogenic emissions ( ''high confidence'' ). { CWGB SRM }

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=== Impacts of Temporary Overshoot ===

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'''B.6 If global warming transiently exceeds 1.5°C in the coming decades or later (overshoot) [[#footnote-013|37]] , then many human and natural systems will face additional severe risks, compared to remaining below 1.5°C ( '''''high confidence''''' ). Depending on the magnitude and duration of overshoot, some impacts will cause release of additional greenhouse gases ( '''''medium confidence''''' ) and some will be irreversible, even if global warming is reduced ( '''''high confidence''''' )   Expand [[#box-spm-1|Box SPM.1]] [[#figure-spm-3|Figure SPM.3]] Links to chapters 2.5, 3.4, 12.3, 16.6, CCB DEEP, CCB SLR'''
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'''B.6.1''' While model-based assessments of the impacts of overshoot pathways are limited, observations and current understanding of processes permit assessment of impacts from overshoot. Additional warming, e.g., above 1.5°C during an overshoot period this century, will result in irreversible impacts on certain ecosystems with low resilience, such as polar, mountain, and coastal ecosystems, impacted by ice-sheet, glacier melt, or by accelerating and higher committed sea level rise ( ''high confidence'' ). [[#footnote-012|38]] Risks to human systems will increase, including those to infrastructure, low-lying coastal settlements, some ecosystem-based adaptation measures, and associated livelihoods ( ''high confidence'' ), cultural and spiritual values ( ''medium confidence'' ). Projected impacts are less severe with shorter duration and lower levels of overshoot ( ''medium confidence'' ). { 2.5, 3.4, 12.3, 13.2, 16.5, 16.6, [https://www.ipcc.ch/chapter/spm#CCP1.2 CCP1.2] , [https://www.ipcc.ch/chapter/spm#CCP2.2 CCP2.2] , [https://www.ipcc.ch/chapter/spm#CCP5.3 CCP5.3] , [https://www.ipcc.ch/chapter/spm#CCP6.1 CCP6.1] , [https://www.ipcc.ch/chapter/spm#CCP6.2 CCP6.2] , CCB SLR, WGI AR6 SPM B.5, WGI AR6 SPM C.3, SROCC 2.3, SROCC 5.4 }

'''B.6.2''' Risk of severe impacts increase with every additional increment of global warming during overshoot ( ''high confidence'' ). In high-carbon ecosystems (currently storing 3,000 to 4,000 GtC) [[#footnote-011|39]] such impacts are already observed and are projected to increase with every additional increment of global warming, such as increased wildfires, mass mortality of trees, drying of peatlands, and thawing of permafrost, weakening natural land carbon sinks and increasing releases of greenhouse gases ( ''medium confidence'' ). The resulting contribution to a potential amplification of global warming indicates that a return to a given global warming level or below would be more challenging ( ''medium confidence'' ). { 2.4, 2.5, [https://www.ipcc.ch/chapter/spm#CCP4.2 CCP4.2] , WGI AR6 SPM B.4.3, SROCC 5.4 }

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<span id="c-adaptation-measures-and-enabling-conditions"></span>