Climate change in the Arctic

The effects of global warming in the Arctic include rising temperatures, loss of sea ice, and melting of the Greenland ice sheet. Potential methane release from the region, especially through the thawing of permafrost and methane clathrates, is also a concern. Because of the amplified response of the Arctic to global warming, it is often seen as a leading indicator of global warming. The melting of Greenland's ice sheet is linked to polar amplification.

According to the Intergovernmental Panel on Climate Change, "warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world." The period of 1995-2005 was the warmest decade in the Arctic since at least the 17th century, with temperatures 2 °C (3.6 °F) above the 1951-1990 average. Some regions within the Arctic have warmed even more rapidly, with Alaska and western Canada's temperature rising by 3 to 4 °C (5.40 to 7.20 °F). This warming has been caused not only by the rise in greenhouse gas concentration, but also the deposition of soot on Arctic ice. A 2013 article published in Geophysical Research Letters has shown that temperatures in the region haven't been as high as they currently are since at least 44,000 years ago and perhaps as long as 120,000 years ago. The authors conclude that "anthropogenic increases in greenhouse gases have led to unprecedented regional warmth."

The poles of the Earth are more sensitive to any change in the planet's climate than the rest of the planet. In the face of ongoing global warming, the poles are warming faster than lower latitudes. The primary cause of this phenomenon is ice-albedo feedback, whereby melting ice uncovers darker land or ocean beneath, which then absorbs more sunlight, causing more heating. The loss of the Arctic sea ice may represent a tipping point in global warming, when 'runaway' climate change starts, but on this point the science is not yet settled.

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