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Arctic undergoing widespread and sustained climate changes

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This past year and the years before it contained strong evidence that the Arctic environment has undergone widespread and sustained changes occurring at a faster-than-anticipated rate, says the National Oceanic and Atmospheric Administration.

Among the unprecedented events witnessed in 2012 was a nearly ice sheet-wide melt on Greenland. Melting ice contributes directly to sea level rise, and it also accelerates the further loss of ice cover by lubricating the underside of glaciers, accelerating their flow, further contributing to sea level rise. Surface melt also makes ice less reflective, decreasing its albedo, causing it to absorb more sunlight and so enter into a self-reinforcing loop of melting more. As a result, the effects of global warming are stronger in the Arctic by a factor of two or more than at lower altitudes, Don Perovich, a Dartmouth College adjunct professor said (.pdf) in late 2012.

Arctic sea ice reaches its lowest summer minimum yet on Sept. 16, when it constituted just 1.3 million square miles. Each of the past 6 years has set a new minimum record dating back to when satellite observation began in 1979.    

NOAA also notes that snow cover in high latitudes in North America and Eurasia hit new record lows in June. In the Northern Hemisphere, the rate of snow cover between 1979 and 2012 declined by 17.6 percent, a rate faster than that of sea ice loss.

For more:
- go to a NOAA Arctic report card for 2012

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