Shock and Thaw—Alaskan Sea Ice Just Took a Steep, Unprecedented Dive

by Guest Sun May 06, 2018 12:24 am

April should be prime walrus hunting season for the native villages that dot Alaska’s remote western coast. In years past the winter sea ice where the animals rest would still be abundant, providing prime targets for subsistence hunters. But this year sea-ice coverage as of late April was more like what would be expected for mid-June, well into the melt season. These conditions are the continuation of a winter-long scarcity of sea ice in the Bering Sea—a decline so stark it has stunned researchers who have spent years watching Arctic sea ice dwindle due to climate change.

Winter sea ice cover in the Bering Sea did not just hit a record low in 2018; it was half that of the previous lowest winter on record (2001), says John Walsh, chief scientist of the International Arctic Research Center at The University of Alaska Fairbanks. “There’s never ever been anything remotely like this for sea ice” in the Bering Sea going back more than 160 years, says Rick Thoman, an Alaska-based climatologist with the National Oceanic and Atmospheric Administration.

A confluence of conditions—including warm air and ocean temperatures, along with persistent storms—set the stage for this dramatic downturn in a region that to date has not been one of the main contributors to the overall reduction of Arctic sea ice. Whereas a degree of random weather variability teed up this remarkable winter, the background warming of the Arctic is what provides the “extra kick” to reach such unheard-of extremes, Walsh says.

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SOURCE SCIENTIFIC AMERICAN