Summit County Citizens Voice

Arctic sea ice extent dipped down toward historic low levels by the end of May. GRAPH COURTESY NATIONAL SNOW AND ICE DATA CENTER.

Average May sea ice extent has been declining by 2.3 percent per decade

By Summit Voice

SUMMIT COUNTY — After hovering near average in April, Arctic sea ice melted rapidly in early May, dipping to near the extent seen in 2007, when the year ended with a record low sea ice extent.

But in the monthly update, scientists at the National Snow and Ice Data Center said there is little historic correlation between May levels and the extent at the end of the melt season in September.

For the month, Arctic sea ice extent averaged 5.07 million square miles, which is about 185,000 square miles below the 1979 to 2000 average. Record low sea ice extent during the satellite measurement era was in 2004.

The greatest sea ice extent was in the Bering Sea, continuing a pattern that lasted all winter and spring. On the other side of the Arctic, unusually low sea ice extent was measured in the Barents and Kara Seas. By the end of May, open water areas had begun to form along some parts of Arctic Ocean coast.

On May 29, 2012, open water is apparent between fast ice along the coast and the broken-up floes off-shore. SATELLITE IMAGE COURTESY NASA.

Air temperatures for May were higher than usual over the central Arctic Ocean and the Canadian Archipelago. Over the Bering Sea, Hudson Bay, and parts of the East Greenland and Norwegian seas, temperatures were slightly below average.

May is not the best to get a handle on overall trends in sea ice, as the data show the least amount of variability in the spring. Including this year, the linear rate of decline for the Month of May is 2.3 percent per decade.

While the May trend may not be as pronounced as other times of the year, the patches of open water already seen in the Beaufort and Laptev seas could lead to more rapid melting as the year goes on, as the darker water between the ice floes absorbs more incoming solar radiation.

Filed under: climate and weather, global warming Tagged: | Arctic sea ice extent, climate, global warming, Measurement of sea ice, National Snow & Ice Data Center