Editing IPCC:AR6/SROCC/Chapter-1 (section)

=== 1.5.2 Exposure of Natural Systems, Ecosystems, and Human Systems ===

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Exposure to hazards in cryosphere systems occur in the immediate vicinity of cryosphere components, and at regional to global scales where cryosphere changes link to other natural systems. For example, decreasing Arctic sea ice increases exposure for organisms that depend upon habitats provided by sea ice, but also has far-reaching impacts through the resulting direct albedo feedback and amplification of Arctic climate warming (e.g., Pistone et al., 2014) that then locally increases surface melting of the Greenland ice sheet (Liu et al., 2016 <sup>[[#fn:r236|236]]</sup> ; Stroeve et al., 2017 <sup>[[#fn:r237|237]]</sup> ). Additionally, ice loss from ice sheets contribute to the global-scale exposure of sea level rise, and more local-scale modifications and losses of coastal habitats and ecosystems (Sections 3.2.3 and 4.3.3.5). Interactions within and between natural systems also influence the spatial reach of risks associated with cryosphere change. Permafrost degradation, for example, interacts with ecosystems and climate on various spatial and temporal scales, and feedbacks from these interactions range from local impacts on topography, hydrology and biology, to global-scale impacts via biogeochemical cycling (e.g., methane release) on climate (Sections 2.2, 2.3, 3.4; Kokelj et al., 2015 <sup>[[#fn:r238|238]]</sup> ; Grosse et al., 2016 <sup>[[#fn:r239|239]]</sup> ).

Exposure to climate change risk exists for virtually all coastal organisms, habitats and ecosystems (Section 5.2), through processes such as inundation and salinisation (Section 4.3), ocean acidification and deoxygenation (Sections 3.2.3, 5.2.3), increasing marine heatwaves (Section 6.4.1.2), and increases in harmful algal blooms and invasive species (Glibert et al., 2014 <sup>[[#fn:r240|240]]</sup> ; Gobler et al., 2017 <sup>[[#fn:r241|241]]</sup> ; Townhill et al., 2017 <sup>[[#fn:r242|242]]</sup> ; Box 5.3). Aggregate impacts of multiple drivers are dramatically altering ecosystem structure and function in the coastal and open ocean (Boyd et al., 2015 <sup>[[#fn:r243|243]]</sup> ; Deutsch et al., 2015 <sup>[[#fn:r244|244]]</sup> ; Przeslawski et al., 2015 <sup>[[#fn:r245|245]]</sup> ), such as coral reefs under increasing pressure from both rising ocean temperature and acidification (Section 5.3.4). Increasing exposure to climate change hazards in open ocean natural systems includes ocean acidification (O’Neill et al., 2017 <sup>[[#fn:r246|246]]</sup> ; Section 5.2.3), changes in ocean ventilation, deoxygenation (Shepherd et al., 2017 <sup>[[#fn:r247|247]]</sup> ; Breitburg et al., 2018 <sup>[[#fn:r248|248]]</sup> ; Section 5.2.2.4), increased cyclone and flood risk (Section 6.3.3) and an increase in extreme El Niño and La Niña events (Section. 6.5.1). Heat content is rapidly increasing within the ocean (Section 5.2.2) and marine heat waves are becoming more frequent across the world ocean (Section 6.4.1).

People who live close to the ocean and/or cryosphere, or depend directly on their resources for livelihoods, are particularly exposed to climate change impacts and hazards ( ''very high confidence'' ) (Barange et al., 2014 <sup>[[#fn:r249|249]]</sup> ; Romero-Lankao et al., 2014 <sup>[[#fn:r250|250]]</sup> ; AMAP, 2015 <sup>[[#fn:r251|251]]</sup> ). These exposures can result in infrastructure damage and failure (Sections 2.3.1.3, 3.4.3, 3.5., 4.3.2), loss of habitability (Sections 2.3.7, 3.4.3, 3.5, 4.3.3), changes in air quality (Section 6.5.2), proliferation of disease vectors (Sections 3.4.3.2.2, 5.4.2.1.1), increased morbidity and mortality due to injury, infectious disease, heat stress, and mental health and wellness challenges (Section 3.4.3.3), compromised food and water security (Sections 2.3.1, 3.4.3.3, 4.3.3.6, 5.4.2.1, 6.8.4), degradation of ecosystem services (Sections 2.3.1.2, 2.3.3.4, 4.3.3, 5.4.1, 6.4.2.3), economic and non-economic impacts due to reduced production and social network system disruption (Section 2.3.7), conflict (Sections 2.3.1.14, 3.5) and widespread human migration (Sections 2.3.7, 4.4.3.5; Oppenheimer et al., 2014 <sup>[[#fn:r252|252]]</sup> ; van Ruijven et al., 2014 <sup>[[#fn:r253|253]]</sup> ; AMAP, 2015 <sup>[[#fn:r254|254]]</sup> ; Cunsolo and Ellis, 2018 <sup>[[#fn:r255|255]]</sup> ).

This report documents how people residing in coastal and cryosphere regions are already exposed to climate change hazards, and which of these hazards are projected to increase in the future. For example, mountain communities have been exposed to increased rockfall, rock avalanches and landslides due to permafrost degradation and glacier shrinkage, and to changes in snow avalanche type and seasonal timing (Section 2.3.1). Cryosphere changes that can impact water availability in mountain regions and for downstream populations (Sections 2.3.1, 2.3.4, 2.3.5) have implications for drinking water, irrigation, livestock grazing, hydropower production and tourism (Section 2.3). Some declining mountain glaciers hold sacred and symbolic meanings for local communities who will experience spiritual losses (Section 2.3.4, 2.3.5, and 2.3.6). Exposures to extreme warming, and continued sea ice and permafrost loss in the Arctic, challenge Indigenous communities with close interdependent relationships of economy, lifestyles, cultural identity, self-sufficiency, Indigenous knowledge, health and wellbeing with the Arctic cryosphere (Section 3.4.3, 3.5).

The population living in low elevation coastal zones (land less than 10 m above sea level) is projected to increase to more than one billion by 2050 (Section 4.3.2.2). These people and communities are particularly exposed to future sea level rise, rising ocean temperature (including marine heat waves; Section 6.4), enhanced coastal erosion, increasing wind, wave height, storm intensity and ocean acidification (Section 4.3.4). These exposures bring associated risks for livelihoods linked to fisheries, tourism and trade, as well as loss of life, damaged assets, and disruption of basic services including safe water supplies, sanitation, energy and transportation networks (Chapters 4, 5, and 6; Cross-Chapter Box 9).

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