Arctic sea ice extent lowest on record

The Arctic sea ice appears to have reached its maximum extent for the winter, but that maximum is the lowest on record, the National Snow and Ice Data Center has reported. The annual ice melt got under way on Feb. 25, an earlier date than normal, with the ice extent at 5.61 million miles. That was 50,200 square miles below the previous lowest extent, recorded in 2011. Satellite observation of the polar sea ice began in 1979.

The 1981 to 2010 average for the maximum sea-ice extent was 6.04 million square miles, NSIDC said.

This year there are below-average ice conditions everywhere except in the Labrador Sea and Davis Strait, NSIDC said. However, since Feb. 25 the sea-ice extent trend has flattened, with recent ice growth in the Bering Sea partly offset by continuing ice retreat in the Barents and Kara seas. And a late-season surge in sea-ice growth is still possible, NSIDC said.

NSIDC attributes relatively low ice growth this winter to weather patterns in which an unusual configuration of the jet stream caused abnormally warm conditions on the Pacific side of the Arctic. This warm weather resulted in abnormally low ice extents in the Bering Sea and the Sea of Okhotsk.

During the first half of March a positive “Arctic oscillation” pattern, a situation in which air pressure over the Arctic is lower than normal, led to a pattern of strong southerly surface winds over the Barents and Kara seas, with temperatures throughout the eastern Arctic being several degrees Celsius above average, NSIDC said. And, while weather forecasts indicate a continuing pattern of warm weather in the east, colder than average conditions are expected over the Bering Sea, NSIDC said.

- Alan Bailey