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Cool conditions slowed Arctic ice melt NSIDC discusses the circumstances behind this year’s minimum Arctic sea ice extent, the highest since 2014 but 12th lowest recorded
Alan Bailey Petroleum News
The National Snow and Ice Data Center has published its analysis of the circumstances leading to this year’s Arctic sea ice minimum extent on Sept. 16. As previously reported by Petroleum News, this year’s minimum extent, at 1.82 million square miles, was the highest since 2014. However, the extent was the 12th lowest that has been recorded - overall, the minimum extent has been declining at an average rate of 13% per decade since 1979. NSIDC also cautioned that at the time of this year’s sea ice minimum, the extent of thick, multiyear sea ice reached a near record low.
A number of factors NSIDC said that a number of factors impacted this year’s minimum extent. There were relatively low sea level atmospheric pressures over the Arctic during the summer, and the Beaufort Gyre, the ocean circulation north of Alaska and Canada, was relatively weak. A relatively large number of “cold cored” Arctic cyclones then accounted for fairly cool summer weather.
The sea surface temperatures remained relatively cool, with these temperatures being recorded as lower than in the previous three years at a number of locations. Widespread areas of near freezing surface sea temperatures near the edge of the sea ice cover during the summer indicated that the ice melt was cooling the water surface, with little incoming solar radiation.
However, the spring and summer saw an extremely early ice melt and retreat in the Laptev Sea, leading to a record low June extent in that region. On the other hand the sea ice retreat in the Beaufort and Chukchi Seas was very slow. The ice edge in the Beaufort and Chukchi remained near average throughout the summer, in part because of the transport of an unusually large amount of thick, multiyear ice into the region during the winter - thicker ice tends to be more resistant to melting than young, thin ice.
Also, because of the wind patterns this year, less ice than usual was transported south out of the Arctic Ocean through the Fram Strait into the East Greenland Sea.
High Antarctic ice maximum Interestingly, this year’s Antarctic sea ice maximum extent, recorded in late August, was the fifth highest since records began, although the sea ice extent has been declining rapidly since the maximum was reached. Apparently the Antarctic winter of 2021 was among the coldest on record, primarily because of two extended periods of stronger than average wind systems circling the continent.
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