Editing IPCC:AR6/WGII/Chapter-14 (section)

=== 14.6.2 Key Risks Across Sectors in North America ===

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===== KR1: In the public and policy domains, divergent perceptions of anthropogenic climate change which pose a risk of inaction on adaptation efforts to reduce exposure and socioeconomic vulnerability =====

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Complex factors, including individual beliefs, ideology, world view, partisan identity as well as societal context, influence how the public, as well as professional groups, communities and policymakers, perceive and understand climate change ( ''high confidence'' ) (Sections 14.3.3, 14.3.4). While there is expert scientific consensus on anthropogenic climate change, rhetoric, misinformation and politicisation of science have contributed to misperceptions ( ''high confidence'' ), polarisation on the severity of impacts and risks to society, indecision and delayed action ( ''high confidence'' ) ( [[#14.3.1|Section 14.3.1]] ). In North America, this impedes adaptation efforts ( [[#14.3.4|Section 14.3.4]] ) and inflates climate risks ( ''high confidence'' ).

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===== KR2: Risk to life, safety and property from intensifying extreme events =====

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Human life and safety across North America, and especially along the coasts of Mexico, the Hawaiian Islands, Gulf of Mexico, Atlantic Canada and southeast USA, will be placed at risk from SLR and severe storms and hurricanes, even at 1.5°C GWL ( ''very high confidence'' ) (Sections 14.5.2, 14.5.5; see Box 14.4). Warming, heatwaves and increases in wildfire activity in many regions of North America pose risks to air quality, health, lives and property (see Box 14.2). More extreme precipitation and flooding pose a risk to human morbidity, mortality and safety in fluvial flood zones and areas downstream of levees, dams and flood culverts. The increasing intensity of storm events poses a risk of landslides, erosion and flooding in shoreline and urban communities, especially high-bank areas along exposed coasts, in Arctic and temperate areas where winter sea ice has diminished and in low-lying coastal areas where SLR and storm surge often overwhelm existing natural coastal features and engineered structures ( [[#14.5.5|Section 14.5.5]] ; see Box 14.4).

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===== KR3: Cumulative damages from climate hazards which pose a substantial risk to economic well-being and shared prosperity =====

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Climate-change impacts are projected to cause large market and non-market damages ( ''high confidence'' ). By end of century under higher GWL scenarios (&gt;4°C), these damages are expected to reach several tens of billions of USD annually in Canada and hundreds of billions annually in the USA. Losses in labour productivity and wages, and damages to coastal properties, will be especially large; however, all sectors in the USA and most sectors in Canada are projected to see substantial relative damages on high-emission pathways by mid- to end of century compared with lower-emission pathways. Economic sectors with hard limits to adaptation (i.e., winter tourism) or that are highly affected by climate variability (i.e., agriculture and fisheries) will be at more risk at lower temperatures than other economic sectors (Sections 14.5.7, 14.5.8). Strategic implementation of adaptation strategies coupled with lower-emissions scenarios result in multi-billion-dollar reductions in economic damages ( [[#14.5.8|Section 14.5.8]] ; see Box 14.6).

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===== KR4: Risk of degradation of marine and coastal ecosystems, including loss of biodiversity, function and related services with cascading effects for communities and livelihoods =====

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Ocean warming will increase the frequency and intensity of MHWs (see Box 14.3), accelerate unprecedented rates of sea ice loss, and alter ocean circulation, chemistry and nutrient cycling in ways that profoundly impact marine productivity, biodiversity and food webs ( ''very high confidence'' ) ( [[#14.5.2|Section 14.5.2]] ). Collectively these impacts pose a risk to nearshore ecological and human systems ( ''high confidence'' ), increasing the probability of phenological mismatches, large-scale redistribution of species, and species population declines ( [[#14.5.4|Section 14.5.4]] ) with cascading impacts that strain cultural and economic systems reliant on marine productivity across North America ( ''high confidence'' ). Nearshore areas of Chesapeake Bay (USA) and Akimiski Island, mid-western James Bay and the coasts in the Pacific ranging from the Gulf of Alaska through Baja Peninsula, have a high proportion of species near their upper thermal limit, and are areas that are particularly susceptible to climate-change risk.

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===== KR5: Risk to major terrestrial ecosystems leading to disruptions of species, ecosystems and their services =====

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Major risks to terrestrial ecosystems across North America, such as semiarid landscapes, rangelands, boreal and temperate forests, and Arctic tundra, include significant ecosystem transformations and shifts in species abundances and ranges, and major vegetation types (e.g., transitions from forests to grasslands), with cascading implications for regional biodiversity ( ''very high confidence'' ). Warming increases the risk of permafrost thaw with propagating impacts on species and communities in the Canadian and US Arctic ( ''high confidence'' ) (CCP6). 6Forest disturbances, including wildfire, drought, insects and pathogens, are expected to increase with warming, acting synergistically to raise the prevalence of tree mortality and ecosystem transformation ( ''medium confidence'' ) ( [[#14.5.1|Section 14.5.1]] ). These changes will reduce services provided by terrestrial ecosystems, including timber yields and carbon sequestration ( ''medium confidence'' ).

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===== KR6: Risk to freshwater resources with consequences for ecosystems, reduced surface water availability for irrigated agriculture and other human uses =====

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Droughts and earlier snowmelt runoff will increase water scarcity during the summer peak water demand period especially in regions with extensive irrigated agriculture, leading to economic losses and increased pressures on groundwater as a substitute for diminished surface water supplies ( ''medium'' to ''high confidence'' ) ( [[#14.5.3|Section 14.5.3]] ). Streams in North America are expected to continue to warm, with important ramifications for aquatic ecosystems ( ''high confidence'' ), reducing habitat for salmon and trout species that are economically and culturally important ( [[#14.5.1|Section 14.5.1]] ). Warming and drying coupled with other stressors (e.g., pollutants, nutrients and invasive species) pose a risk to ecosystem structure and function in lakes, streams and reservoirs across many parts of North America ( ''high confidence'' ) (Sections 14.5.1, 14.5.3). Warming increases in heavy rainfall and nutrient loading pose risks for water quality and HABs ( ''medium'' to ''high confidence'' ) ( [[#14.5.3|Section 14.5.3]] ).

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===== KR7: Risk to human health and well-being, including mental health =====

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Heat-related human mortality is projected to increase in North America as a result of climate change and ageing populations, poverty, chronic diseases and inadequate public health systems ( ''very high confidence'' ) ( [[#14.5.6.1|Section 14.5.6.1]] ). Gradual changes to temperature and precipitation are impacting urban ecosystems and creating ecosystem regime changes resulting in the poleward expansion among insects that bring risks related to vector-borne diseases such as West Nile virus and Lyme disease ( ''high confidence'' ) ( [[#14.5.6|Section 14.5.6]] ). Climate change is expected to lead to wide-ranging mental health challenges related to an increase in the psychological burdens of climate change ( ''high confidence'' ), particularly for individuals with existing mental health conditions, who live in severely impacted areas or who are reliant on climate for livelihoods and cultural well-being (e.g., Indigenous Peoples and farmers) ( [[#14.5.6.8|Section 14.5.6.8]] ).

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===== KR8: Risk to food and nutritional security through changes in agriculture, livestock, hunting, fisheries and aquaculture productivity and access =====

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Cascading and interacting impacts of climate change threatens food systems as well as food and nutritional security for many North Americans, especially those already experiencing food and nutritional scarcity, women and children with high nutritional needs and Indigenous Peoples reliant on subsistence resources ( ''high confidence'' ) ( [[#14.5.6|Section 14.5.6]] ) ''.'' In agricultural regions experiencing aridification and where water scarcity precludes substantial expansion of irrigation, warming and extreme heat pose a risk to food and forage crop and livestock production ( ''high confidence'' ) ( [[#14.5.4|Section 14.5.4]] ). Ocean warming and MHWs will continue to disrupt commercial capture fisheries through species redistribution and changes to yield ( ''high confidence'' ), and warming waters and OA will increasingly impact aquaculture production ( ''high confidence'' ) ( [[#14.5.4|Section 14.5.4]] ). Interactions between competing aspects of human security (e.g., food, energy and water) will be exacerbated by climate change ( ''high confidence'' ) (Sections 14.5.3, 14.5.4, 14.5.8).

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===== KR9: Risks to major infrastructure supporting commerce and trade with implications for sustainable economic development, regional connections and livelihoods =====

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Climate change and extreme events are expected to increase risks to the North American economy via infrastructure damage and deterioration ( ''high confidence'' ), disruption to operations, unsafe conditions for workers ( ''medium confidence'' ) and interruptions to international and inter-regional supply chains ( ''medium confidence'' ) ( [[#14.5.8|Section 14.5.8]] ; see Box 14.5). These climatic impacts will have cascading implications for local livelihoods, sustainable economic development pathways and regional connectivity, and will reinforce pre-existing social inequities ( ''medium confidence'' ). Infrastructure damage will also disrupt economic activities, including manufacturing, tourism, fisheries, natural resource extraction and energy production ( ''high confidence'' ) ( [[#14.5.8|Section 14.5.8]] ).

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===== KR10: Risk to the quality of life in North American communities, cities and towns =====

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In major North American cities and settlements, vulnerability to climate change has increased and is projected to continue to rise ( ''medium confidence'' ) ( [[#14.5.5|Section 14.5.5]] ). Concentrated populations with unequal adaptive capacities, exposure of valuable assets, ageing infrastructure, and differing degrees of institutional capacity and effectiveness will underpin climate hazards ( [[#14.5.5|Section 14.5.5]] ). Coastal, riverine and urban flooding displacing communities and coastal ecosystems ( [[#14.5.5.2|Section 14.5.5.2]] ) will become a dominant risk to urban centres ( ''high confidence'' ) and will cause disruptions to transportation and trade infrastructure ( [[#14.5.8|Section 14.5.8]] ). Large wildfires endangering lives, livelihoods, property and key infrastructure, and economic activities will contribute to compromised air quality and municipal water contamination ( [[#14.5.6|Section 14.5.6]] ; see Box 14.2).

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