Editing IPCC:AR6/SYR/SPM (section)

=== Climate Change Impacts and Climate-Related Risks ===

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'''B.2 For any given future warming level, many climate-related risks are higher than assessed in AR5, and projected long-term impacts are up to multiple times higher than currently observed '''''(high confidence)''''' . Risks and projected adverse impacts and related losses and damages from climate change escalate with every increment of global warming '''''(very high confidence)''''' . Climatic and non-climatic risks will increasingly interact, creating compound and cascading risks that are more complex and difficult to manage '''''(high confidence)''''' . [[#figure-spm-3|Figure SPM.3]] [[#figure-spm-4|Figure SPM.4]] Links to longer report Cross-Section Box.2, 3.1, 4.3, Figure 3.3, Figure 4.3'''
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B.2.1 In the near term, every region in the world is projected to face further increases in climate hazards ( ''medium to high confidence'' , depending on region and hazard), increasing multiple risks to ecosystems and humans ''(very high confidence)'' . Hazards and associated risks expected in the near-term include an increase in heat-related human mortality and morbidity ''(high confidence)'' , food-borne, water-borne, and vector-borne diseases ''(high confidence)'' , and mental health challenges [[#footnote-021|36]] ''(very high confidence)'' , flooding in coastal and other low-lying cities and regions ''(high confidence)'' , biodiversity loss in land, freshwater and ocean ecosystems ( ''medium to very high confidence'' , depending on ecosystem), and a decrease in food production in some regions ''(high confidence)'' . Cryosphere-related changes in floods, landslides, and water availability have the potential to lead to severe consequences for people, infrastructure and the economy in most mountain regions ''(high confidence)'' . The projected increase in frequency and intensity of heavy precipitation ''(high confidence)'' will increase rain-generated local flooding ''(medium confidence)'' . ''[[#figure-spm-3|Figure SPM.3]] [[#figure-spm-4|Figure SPM.4]] Links to longer report Figure 3.2, Figure 3.3, 4.3, Figure 4.3''

B.2.2 Risks and projected adverse impacts and related losses and damages from climate change will escalate with every increment of global warming ''(very high confidence)'' . They are higher for global warming of 1.5°C than at present, and even higher at 2°C ( ''high confidence)'' . Compared to the AR5, global aggregated risk levels [[#footnote-020|37]] (Reasons for Concern [[#footnote-019|38]] ) are assessed to become high to very high at lower levels of global warming due to recent evidence of observed impacts, improved process understanding, and new knowledge on exposure and vulnerability of human and natural systems, including limits to adaptation ''(high confidence)'' . Due to unavoidable sea level rise (see also B.3), risks for coastal ecosystems, people and infrastructure will continue to increase beyond 2100 ''(high confidence)'' . ''[[#figure-spm-3|Figure SPM.3]] [[#figure-spm-4|Figure SPM.4]] Links to longer report 3.1.2, 3.1.3, Figure 3.4, Figure 4.3''

B.2.3 With further warming, climate change risks will become increasingly complex and more difficult to manage. Multiple climatic and non-climatic risk drivers will interact, resulting in compounding overall risk and risks cascading across sectors and regions. Climate-driven food insecurity and supply instability, for example, are projected to increase with increasing global warming, interacting with non-climatic risk drivers such as competition for land between urban expansion and food production, pandemics and conflict. ''(high confidence) Links to longer report 3.1.2, 4.3, Figure 4.3''

B.2.4 For any given warming level, the level of risk will also depend on trends in vulnerability and exposure of humans and ecosystems. Future exposure to climatic hazards is increasing globally due to socio-economic development trends including migration, growing inequality and urbanisation. Human vulnerability will concentrate in informal settlements and rapidly growing smaller settlements. In rural areas vulnerability will be heightened by high reliance on climate-sensitive livelihoods. Vulnerability of ecosystems will be strongly influenced by past, present, and future patterns of unsustainable consumption and production, increasing demographic pressures, and persistent unsustainable use and management of land, ocean, and water. 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)'' Links to longer report Cross-Section Box.2, Figure 1c, 3.1.2, 4.3

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'''Figure SPM.3:''' Projected risks and impacts of climate change on natural and human systems at different global warming levels (GWLs) relative to 1850-1900 levels. Projected risks and impacts shown on the maps are based on outputs from different subsets of Earth system and impact models that were used to project each impact indicator without additional adaptation. WGII provides further assessment of the impacts on human and natural systems using these projections and additional lines of evidence. '''(a)''' Risks of species losses as indicated by the percentage of assessed species exposed to potentially dangerous temperature conditions, as defined by conditions beyond the estimated historical (1850-2005) maximum mean annual temperature experienced by each species, at GWLs of 1.5°C, 2°C,3°C and 4°C. Underpinning projections of temperature are from 21 Earth system models and do not consider extreme events impacting ecosystems such as the Arctic. '''(b)''' Risks to human health as indicated by the days per year of population exposure to hyperthermic conditions that pose a risk of mortality from surface air temperature and humidity conditions for historical period (1991-2005) and at GWLs of 1.7°C–2.3°C (mean = 1.9°C; 13 climate models), 2.4°C–3.1°C (2.7°C; 16 climate models) and 4.2°C–5.4°C (4.7°C; 15 climate models). Interquartile ranges of GWLs by 2081-2100 under RCP2.6, RCP4.5 and RCP8.5. The presented index is consistent with common features found in many indices included within WGI and WGII assessments. '''(c)''' Impacts on food production: (c1) Changes in maize yield by 2080-2099 relative to 1986-2005 at projected GWLs of 1.6°C–2.4°C (2.0°C), 3.3°C–4.8°C (4.1°C) and 3.9°C–6.0°C (4.9°C). Median yield changes from an ensemble of 12 crop models, each driven by bias-adjusted outputs from 5 Earth system models, from the Agricultural Model Intercomparison and Improvement Project (AgMIP) and the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Maps depict 2080-2099 compared to 1986-2005 for current growing regions (&gt;10 ha), with the corresponding range of future global warming levels shown under SSP1-2.6, SSP3-7.0 and SSP5-8.5, respectively. Hatching indicates areas where &lt;70% of the climate-crop model combinations agree on the sign of impact. (c2) Change in maximum fisheries catch potential by 2081-2099 relative to 1986-2005 at projected GWLs of 0.9°C–2.0°C (1.5°C) and 3.4°C–5.2°C (4.3°C). GWLs by 2081-2100 under RCP2.6 and RCP8.5. Hatching indicates where the two climate-fisheries models disagree in the direction of change. Large relative changes in low yielding regions may correspond to small absolute changes. Biodiversity and fisheries in Antarctica were not analysed due to data limitations. Food security is also affected by crop and fishery failures not presented here. ''[[#box-spm-1|Box SPM.1]] Links to longer report 3.1.2, Figure 3.2, Cross-Section Box.2''

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'''Figure SPM.4: Subset of assessed climate outcomes and associated global and regional climate risks.''' The burning embers result from a literature based expert elicitation. '''Panel (a): Left''' – 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. ''Very'' ''likely'' ranges are shown for the low and high GHG emissions scenarios (SSP1-2.6 and SSP3-7.0) (Cross-Section Box.2). '''Right''' – Global Reasons for Concern (RFC), comparing AR6 (thick embers) and AR5 (thin embers) assessments. Risk transitions have generally shifted towards lower temperatures with updated scientific understanding. Diagrams are shown for each RFC, assuming low to no adaptation. Lines connect the midpoints of the transitions from moderate to high risk across AR5 and AR6. '''Panel (b)''' : Selected global risks for land and ocean ecosystems, illustrating general increase of risk with global warming levels with low to no adaptation. '''Panel (c): Left''' - Global mean sea level change in centimetres, relative to 1900. The historical changes (black) are observed by tide gauges before 1992 and altimeters afterwards. The future changes to 2100 (coloured lines and shading) are assessed consistently with observational constraints based on emulation of CMIP, ice-sheet, and glacier models, and ''likely'' ranges are shown for SSP1-2.6 and SSP3-7.0. '''Right''' - Assessment of the combined risk of coastal flooding, erosion and salinization for four illustrative coastal geographies in 2100, due to changing mean and extreme sea levels, under two response scenarios, with respect to the SROCC baseline period (1986-2005). The assessment does not account for changes in extreme sea level beyond those directly induced by mean sea level rise; risk levels could increase if other changes in extreme sea levels were considered (e.g., due to changes in cyclone intensity). “No-to-moderate response” describes efforts as of today (i.e., no further significant action or new types of actions). “Maximum potential response” represent a combination of responses implemented to their full extent and thus significant additional efforts compared to today, assuming minimal financial, social and political barriers. (In this context, ‘today’ refers to 2019.) The assessment criteria include exposure and vulnerability, coastal hazards, in-situ responses and planned relocation. Planned relocation refers to managed retreat or resettlements. The term response is used here instead of adaptation because some responses, such as retreat, may or may not be considered to be adaptation. '''Panel (d)''' : Selected risks under different socio-economic pathways, illustrating how development strategies and challenges to adaptation influence risk. '''Left''' - Heat-sensitive human health outcomes under three scenarios of adaptation effectiveness. The diagrams are truncated at the nearest whole ºC within the range of temperature change in 2100 under three SSP scenarios. '''Right''' - Risks associated with food security due to climate change and patterns of socio-economic development. Risks to food security include availability and access to food, including population at risk of hunger, food price increases and increases in disability adjusted life years attributable to childhood underweight. Risks are assessed for two contrasted socio-economic pathways (SSP1 and SSP3) excluding the effects of targeted mitigation and adaptation policies. ''[[#box-spm-1|Box SPM.1]] Links to longer report Figure 3.3''

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