News•November 19, 2012

As Sea Ice Declines, Winter Shifts in Northern Alaska

The consequences of the record loss of Arctic sea ice this past summer are becoming clear to the 4,000 or so residents of Barrow, Alaska, who have seen a much milder and snowier-than-average start to their typically long and bitterly cold winter season.

Temperature departures from average during the past month in Barrow, AK.
Click to enlarge the image.
Credit: NWS Alaska Region.

As is typical for this time of year, much of Alaska has already been plunged into winter conditions, with temperatures below 0°F in some locations. Yet Barrow, which from its perch on Alaska’s North Slope is the country’s northernmost town, has had a downright balmy start to the Alaskan winter. (Well, balmy for Barrow, at least.)

According to the National Weather Service, Barrow has seen “almost continuous above-normal temperatures” since September “due to a lack of sea ice” formation until last week. Along with the above-average temperatures has come above-average snowfall. Snowfall since July 1 has been more than a foot above average, the Weather Service said, with 31.4 inches of snow having fallen through Nov. 17.

The record melt of Arctic sea ice this summer resulted in a broader expanse of open water in the Arctic Ocean. The darker ocean waters absorbed more incoming solar radiation, warming the sea and the lower atmosphere, thereby helping to warm lands that border the Arctic Ocean, such as Barrow. Open water also provides a ready moisture source for precipitation, be it in the form of rain or snow, and this accounts for much of Barrow’s recent snowy spell.

Temperature outlook for December 2012, showing a likelihood for continued above average temperatures along Alaska's North Slope (blue arrow).
Credit: NWS/CPC.

As the Arctic climate has warmed in recent years, fall sea ice cover has often formed later in certain areas, and when it does form, it has tended to be thinner than average. After setting a record low in September, sea ice extent doubled during October but still only managed to recover to the second-lowest extent on record for October, ranking just above 2007.

Studies show that sea ice loss can speed warming of parts of the Far North, thereby helping to melt permafrost and unlock the greenhouse gases currently locked in such frozen lands.

The National Weather Service had predicted the early winter warmth in far northern Alaska. Back in October, when the National Weather Service released its initial winter weather outlook for the winter of 2012-13, forecasters assigned this region the highest odds of any part of the country to have warmer-than-average conditions, due to the lack of sea ice.

In October, Mike Halpert, the deputy director of NOAA’s Climate Prediction Center, said, “Right now there is no ice at all there. We would certainly expect the early winter to be above average [temperature-wise].” More recently, sea ice has rapidly increased around Barrow, which should cut off some of the available moisture for the above average snows that have struck the region, and cut temperatures to more typical levels.