A recent study led by Dr. John Walsh, Chief Scientist at the International Arctic Research Center (IARC) at the University of Alaska Fairbanks, found that the record warm 2015/16 Alaskan cold season could become the new normal by mid-century. The findings were recently published in Journal of Climate in a paper entitled, “The Exceptionally Warm Winter of 2015/16 in Alaska”
In addition to being the warmest on record since 1925, the 2015/16 cold season saw temperatures that 8.4 degrees Farenheit warmer on average than the mean from 1925-2016. The second half of the cold season (January-April) alone had temperatures that were 10.9 degrees warmer on average statewide. This resulted in new record highs during this period for nearly every climate division in the state, with Western and Central Alaska experiencing the greatest overall warming.
So what are some possible factors that could have contributed to these increased temperatures?
One culprit was a massive El Nino, which led to increased surface temperatures in the Equatorial and Northern Pacific Oceans. Low snow cover also impacted surface albedo, the ability to reflect sunlight. Lighter colored surfaces, such as white snow, allow more sunlight to be reflected from the surface back to the atmosphere, which can help keep temperatures cooler on the surface. Darker colored surfaces (grass, water, pavement, etc.) cannot reflect as much light and therefore absorb more incoming sunlight, which can result in warmer surface temperatures. Decreased snow cover -> decreased surface albedo -> increased surface warming.
It is also suspected that anthropogenic, human-induced, greenhouse warming played a role in the intensity of warming and is expected to increase the probability of similar events occurring in the future. There is a 90% probability that temperatures similar to the 2015/16 Alaskan season could be seen again as soon as mid-century.