Air temps in large parts of Arctic more than 10 degrees above average, Antarctic sea ice is at above-average extent
By Summit Voice
SUMMIT COUNTY — With unusually warm air temperatures prevailing over the Arctic for the second year in a row, Arctic sea ice was at its lowest for December since satellite measurements began in 1979. At the same time, sea ice in Antarctica has remained at above average levels for the past four months during the spring melt season, according to a Jan. 5 bulletin from the National Snow and Ice Data Center.
Scientists with the center said sea ice extent average about 4.63 million square miles during December, about 104,000 square miles less than the previous minimum, set in 2006, and 1.35 million less than the 1979 to 2000 average. Since satellite measurements began, the linear rate of decline in Arctic sea ice extent is 3.5 percent per decade.
The ice extent was unusually low on both the Atlantic and Pacific sides of the Arctic, and especially low in Hudson Bay, in the Davis Strait, between Baffin Island and Greenland, and in Hudson Strait, between southern Baffin Island and Labrador. Normally, these areas are completely frozen over by late November.
Researchers attributed the low ice extent to well above-normal air temperatures in areas where the ice would normally be expanding this time of year. Air temperatures over eastern Siberia were 11 to 18 degrees above normal in December. Over the eastern Canadian Arctic Archipelago, Baffin Bay/Davis Strait and Hudson Bay, temperatures were at least 11 degrees higher than average.
Southern Baffin Island had the largest anomalies, with temperatures more than 18 degrees Fahrenheit higher than normal. In sharp contrast, temperatures were 7 to 13 degrees lower than average over the Alaska-Yukon border, north-central Eurasia, and Scandinavia.
The warm temperatures in December came from two sources: Unfrozen areas of the ocean continued to release heat to the atmosphere, and an unusual circulation pattern brought warm air into the Arctic from the south. Although the air temperatures were still below freezing on average, the additional ocean and atmospheric heat slowed ice growth.
In a pattern repeated from last year, a strong negative phase of the Arctic Oscillation dominated the middle and high latitudes of the Northern Hemisphere in December 2010, bringing higher-than-normal pressures to the Arctic region, with lower-than-normal pressures in middle latitudes.
This year the higher pressures are centered near Iceland and the eastern tip of the Aleutians in the Pacific, yielding a different pattern of winds. As a result, different areas experienced warm anomalies in 2010, and a different pattern of ice extent emerged.
Filed under: climate and weather, Environment, global warming, Summit County Colorado Tagged: | antarctic sea ice, Arctic, Arctic sea ice, Baffin Island, Canadian Arctic Archipelago, Environment, global warming, National Snow and Ice Data Center, Polar ice packs, Summit County News