Arctic sea ice just reached the second lowest winter maximum on record

On March 17, sea ice reached this season's maximum extent, just a bit higher than the record low set last year.

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A map from the National Snow and Ice Data Center shows Arctic sea ice extent on March 17, 2018, when it reached its seasonal maximum of 14.48 million square kilometers (5.59 million square miles). The orange line represents the average extent for that day during the period from 1981 to 2010. (National Snow and Ice Data Center)

Arctic sea ice has begun its annual melt after reaching the second-lowest winter maximum extent in the 39-year satellite record.

The maximum extent of 14.48 million square kilometers (5.57 million square miles), reached on March 17, was barely above the record-low 14.42 million square kilometers (5.59 million square miles) posted last year, the National Snow and Ice Data Center reported on Friday.

All four of the lowest winter maximums have been in the last four years, part of a trend of unusual winter heat waves in the Arctic, the Colorado-based center said.

Ice this year has been particularly low on the Pacific side of the Arctic. In the Chukchi Sea, the freeze-up came at least a month later than normal.

In the Bering Sea, where ice retreated dramatically in February before some refroze in March, the maximum winter extent was “by far” the lowest in the satellite record, said Rick Thoman, climate science and services manager for the National Weather Service in Alaska.

The low-ice conditions had effects on local communities. Vast areas of open water in February set up unseasonal coastal flooding that closed the local heliport and briefly inundated the power plant on Little Diomede Island, U.S. and Canadian weather services reported. The late freeze-up in the Chukchi and northern Bering seas affected the quality of ice there, leaving it thin and with less snow cover than normal, Thoman said.

“The dice are really loaded towards early breakup,” he said.”The whole Pacific side looks terrible for ice melt in spring and summer.”

Ice was also low this winter in the Barents Sea on the Atlantic side, the National Snow and Ice Data Center said.

The warm winter conditions in the Arctic have been tied to jet stream disruptions and extreme winter weather in more southern latitudes. A study published this month in the journal Nature Communications links the Arctic heat waves associated with low winter sea ice to extreme winter weather in the middle latitudes, especially on the U.S. East Coast.

This winter’s Arctic ice conditions are also being invoked in a legal fight being waged on the Trump administration an environmental group.

The Center for Biological Diversity, which is suing the administration to try to compel Endangered Species Act protections for ice-dependent Pacific walruses, cited the near-record low maximum as evidence supporting its court case,

“This is devastating news for Arctic wildlife like polar bears and walruses that depend on sea ice for survival,” Shaye Wolf, the organization’s climate science director, said in a statement. “Because of the failure to rein in carbon pollution, these amazing animals are suffering as their habitat melts away even faster than we predicted. But the Trump administration is failing to protect them.”

Yereth Rosen is a 2018 Alicia Patterson Foundation fellow.