Climate Change 2001: Working Group II: Impacts, Adaptation and Vulnerability

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Feedbacks and Interactions

Climate change and global warming will affect key polar drivers of further climate change. These effects will have impacts that affect other regions of the world. Models indicate that once triggered, these impacts will continue for centuries and lead to further change elsewhere in the world:

• Warming will reduce sea-ice and snow extent, particularly in the Arctic, causing additional heating of the surface—which, in turn, will further reduce ice/snow cover.*****
• Deep ocean water around the Antarctic and in the north Atlantic is a crucial part of the ocean's thermohaline circulation. Its rate of production is likely to decrease because of freshening of waters from increased Arctic runoff from glacial icemelt, from increases in precipitation over evaporation, and from reduced sea-ice formation. Models indicate that the impact will be a prolonged, major slowing of the thermohaline circulation and ocean ventilation, even with stabilization of greenhouse gases (GHGs).***
• Polar regions have oceans, wetlands, and permafrost that act as major sources and sinks for atmospheric CO₂ and methane (CH₄) over vast areas. Projected climate change will alter these features and increase their contributions to GHGs. The Southern Ocean's uptake is projected to decline; CO₂ emissions from Arctic tundra may rise initially as a result of changes in water content, peat decomposition, and thawing of permafrost.***

Vulnerability and Adaptation

• Localities within the Antarctic and Arctic where water is close to its melting point are highly sensitive to climate change; this sensitivity renders their biota and socioeconomic life particularly vulnerable to climate change. In the Antarctic Peninsula, as ice melts, changes are likely to be rapid, but overall the Antarctic and the Southern Ocean are likely to respond relatively slowly to climate change, so there will be less impact in this region compared with elsewhere by 2100. Nevertheless, climate change in the Antarctic will initiate processes that could last for millennia—long after greenhouse emissions have stabilized—and these changes will cause irreversible impacts on ice sheets, oceanic circulation of water, and sea-level rise.
• The Arctic is extremely vulnerable to climate change, and major ecological, sociological, and economic impacts are expected. A variety of positive feedback mechanisms induced by climate change are likely to operate in the Arctic; these mechanisms will cause rapid and amplified responses, with consequential impacts on the thickness and extent of sea ice, thawing of permafrost, runoff into the Arctic Ocean, and coastal erosion.
• Biota are particularly vulnerable to climate change in the polar regions. Less sea ice will reduce ice edges, which are prime habitats for marine organisms. Habitat loss for some species of seal, walrus, and polar bear results from ice melt, and apex consumers—with their low-reproductive outputs—are vulnerable to changes in the long polar marine food chains.
• Adaptation to climate change in natural polar ecosystems is likely to occur through migration and changing species assemblages, but the details of these effects are unknown. Some animals may be threatened (e.g., walrus, polar bear, and some species of seal), whereas others may flourish (e.g., some species of fish and penguins).
• Loss of sea ice in the Arctic will provide increased opportunities for new sea routes, fishing, and new settlements, but also for wider dispersal of pollutants. Collectively, these changes emphasize the need for an adequate infrastructure to be in place before they occur. Disputes over jurisdiction in Arctic waters, sustainable development of fisheries and other marine resources, and construction of navigational aids and harbor facilities, as well as problems arising from oil and gas development, including pollution and environmental monitoring, will all have to be resolved by polar and associated nations as climate-induced change becomes widespread. Just as important is the need for new building codes for roads, railways, runways, and buildings to cope with the effects of permafrost thawing.
• Although most indigenous peoples are highly resilient, the combined impacts of climate change and globalization create new and unexpected challenges. Because their livelihood and economy increasingly are tied to distant markets, they will be affected not only by climate change in the Arctic but also by other changes elsewhere. Local adjustments in harvest strategies and in allocation of labor and capital will be necessary. Perhaps the greatest threat of all is to maintenance of self-esteem, social cohesion, and cultural identity of communities.