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State and trends


Key messages: A rapidly changing Arctic


The Arctic is experiencing a profound transformation that is having important impacts on North America and the world as a whole. These rapid changes in the Arctic are driven largely by interacting forces of climate change and increased human activities.


• As one of the first areas of the world to experience the impacts of climate change, the Arctic region serves as a barometer for change in the rest of the world.


• The Arctic’s unique underlying social, institutional, and ecological patterns make this area highly vulnerable to continued climate change, especially in light of the difficulties for the region to adapt, which may trigger cascading risks.


• Warming in the Arctic has increased at twice the global average since 1980. Other prominent processes that signal greater climate change impacts include glacier and ice sheet melt, altered salinity concentrations and ocean circulation patterns, sea level rise, and ocean acidification.


• While the strong adaptive capabilities of Arctic peoples have served them well over the centuries, there is growing concern that their distinct and traditional ways of life will be irrevocably affected by the profound transformation taking place so rapidly across the region.


This results from a general warming trend on land, as well as permafrost thaws, which together with increased greenhouse gas emissions into the atmosphere, reinforce a biophysical feedback loop. The warmer the temperature, the more melting; the more melting, the greater greenhouse gas emissions that then lead to higher temperatures. The change in albedo from the loss of snow and ice in the north– absorbing the sun’s heat rather than reflecting it–further escalates climate change (NSIDC 2015).


2.7.3 Amplification explained


At near ground level, the northern hemisphere high latitudes are warming at double the rate of lower latitudes: this is Arctic amplification. It occurs all year round, but is strongest in autumn and winter. Several processes contribute to it, including local radiative effects from increased greenhouse gas forcing, changes in the surface albedo feedback induced by a diminishing snow and ice cover, changes in aerosol


concentrations and deposits of black carbon on snow and ice surfaces, changes in Arctic cloud cover and water vapour content, and the slowing rate of release to space of long- wave radiation in the Arctic (Figure 2.7.2). In addition to these local drivers, Arctic conditions vary in response to changes in heat and moisture transported into the Arctic from lower latitudes (Cohen 2014; Stocker et al. 2013).


2.7.4 Thawing permafrost and its consequences


The frozen ground of the Arctic is an important but poorly understood element of the entire Arctic and its connections to the global climate. There are trillions of tonnes of carbon frozen in the permafrost of Arctic soils. For millions of years, these carbon stores have not interacted with the atmosphere or hydrosphere. Now they are, or soon will be, affecting the rates and magnitude of global warming (NAS 2015). Although the Polar Research Board of the US National Academy of Science concludes that the near term


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