2.2 Climate variability and change in Alaska

Monday, 20 June 2005: 1:45 PM
North & Center Ballroom (Hilton DeSoto)
Martha Shulski, Univ. of Alaska, Fairbanks, AK; and G. Wendler

Since 1950 there has been an overall increase in the mean annual temperature for each of Alaska's different climate regions. The increase is about 3°F statewide but is strongest for the interior and less for the maritime regions along the southern coast. However, for most locations this change is highly non-linear and includes a step increase in the mid 1970's. The change is also not uniform seasonally, in which the greatest temperature increase is found in the winter and spring, less change in summer, and even a slight cooling in autumn. The occurrence of extreme low temperatures have been found to decrease, more so than extreme high temperatures. Long-term precipitation trends show that there is a general increase since 1950 for Alaska of about 10%, with the exception of the Arctic coast.

The combined effect of the precipitation increase and slight cooling trend in autumn for interior Alaska has resulted in a slight shift toward an earlier onset of the seasonal snowpack. The strong warming in spring, however, has resulted in an earlier disappearance of the snowpack giving an overall shift in the period of continuous snow cover. Total precipitation has been found to increase in southeast Alaska at stations near sea level, but with a concurrent decrease in snowfall, therefore more of the precipitation falls as liquid rather than solid type at low elevations. Temperatures in this region during the cold season are just below or near freezing and with the observed warming trend there is a higher frequency of days above freezing owing to the shift in precipitation type.

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