Warm winters will be the norm by midcentury
Remember Alaska's "nonwinter" of 2015-16, which left snowplowing companies bereft of business, and skiers and mushers simply bereft?
That will be an average winter by midcentury, a University of Alaska Fairbanks climate expert said Monday.
It was the second-warmest winter on record for Alaska, with an average December-to-January temperature that was 10.7 degrees Fahrenheit above the 20th century average, and part of what became the state's warmest year on record.
But a few decades from now, such winters will not be outliers but will be typical, said John Walsh, chief scientist at UAF's International Arctic Research Center.
"That winter seems to be a preview of the Alaska winters in the 2040s and 2050s," Walsh said in a presentation at a climate-prediction workshop in Anchorage.
The change to a new winter norm is fairly close at hand, he noted. "That's only 30 years from now," he said.
And if 2015-16 winter conditions become the average, that means some of the future winters will be even warmer, he said.
The winter of 2015-16 was 3.9 degrees Celsius (7 degrees Fahrenheit) higher than the 1981-2010 average, Walsh said in his presentation. Only 1 degree Celsius — 1.8 degrees Fahrenheit — of that winter's average temperature was attributable to short-term and random weather fluctuations, he said.
The rest of the warming came from longer-term factors — climate-changing greenhouse gas concentrations in the atmosphere, reduced Arctic sea ice and warmed-up ocean waters.
Those long-term factors, added to short-term weather conditions, made the season a "perfect storm" for warm conditions, Walsh said.
Those factors also warmed the just-completed winter of 2016-17, he said.
Despite an unusually cold March in Alaska, the December-to-March statewide average was almost exactly the same as the 20th century average, according to National Oceanic and Atmospheric Administration data.
It would have been 2.1 degrees Celsius (3.8 degrees Fahrenheit) lower, Walsh said, but for the warming effects of greenhouse gas concentrations, low Arctic sea ice and lingering warmth in nearby ocean waters. Those factors made the difference "between what we deserved in the winds and what we really got," he said.