A Century of Climate Change for Fairbanks, Alaska

Abstract

Climatological observations are available for Fairbanks, Interior Alaska, for up to 100 years. This is a unique data set for Alaska, insofar as it is of relatively high quality and without major breaks. Applying the best linear fit, we conclude that the mean annual temperature rose from-3.6°C to-2.2°C over the century, an increase of 1.4°C (compared to 0.8°C worldwide). This comparison clearly demonstrates the well-known amplification or temperature change for the polar regions. The observed temperature increase is neither uniform over the time period nor uniform throughout the course of a year. The winter, spring, and summer seasons showed a temperature increase, while autumn showed a slight decrease in temperature. For many activities, the frequencies of extremes are more important than the average values. For example, the frequency of very low temperatures (below-40°C, or-40°F) has decreased substantially, while the frequency of very high temperatures (above 26.7°C, or 80°F) increased only slightly. Finally, the length of the growing season increased substantially (by 45%) as a result of an earlier start in spring and a later first frost in autumn. Precipitation decreased for Fairbanks. This is a somewhat counter-intuitive result, as warmer air can hold more water vapor. The date of the establishment of the permanent snow cover in autumn showed little change; however, the melting of the snow cover now occurs earlier in the spring, a finding in agreement with the seasonal temperature trends. The records for wind, atmospheric pressure, humidity, and cloudiness are shorter, more broken, or of lower quality. The observed increase in cloudiness and the decreasing trend for atmospheric pressure in winter are related to more advection and warmer temperatures during this season.

The Browning of Alaska’s Boreal Forest

“…This warming has led to substantial physical and biological changes including record sea-ice retreat [2], permafrost thawing [3], record summer warmth [4], and an increase in growing season length [5]. In the arctic tundra, there has been an increase in vegetation productivity as indexed by the Normalized Difference Vegetation Index (NDVI) [6], consistent with field-based historic photography [7], and experimental warming studies [8].…”

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

“…The importance of this result depends, in part, on the spatial extent and intensity of precipitation changes across the boreal and Arctic during this century. There is a detectable anthropogenic influence in high-latitude precipitation changes (Wan et al, 2015), but these changes are inconsistent: drier and warmer conditions in boreal Eurasia (Buermann et al, 2014), for example, but growing season length increases in interior Alaska with no increase in precipitation (Wendler and Shulski, 2009). This spatial variability will interact with permafrost thaw dynamics to produce a complex patchwork of soil moisture changes (Zhang et al, 2012;Watts et al, 2012).…”

Sources and sinks of carbon in boreal ecosystems of interior Alaska: A review

“…Future climate scenarios project a 3-7°C increase in mean annual air temperatures for the Alaskan interior over the next 90 years (Chapman and Walsh, 2007;Walsh et al, 2008). In addition to this increase in mean annual temperatures, the occurrence of extreme low temperatures (characterized by temperatures <-40°C) has decreased on average from 14 to 8 days annually (Wendler and Shulski, 2009). A non-statistically significant 11% decrease in annual precipitation has occurred over the last 90 years near Fairbanks (Wendler and Shulski, 2009) with the strongest decreases in precipitation occurring in spring followed by winter.…”