What was done
The authors used near-surface air temperature data obtained from all 19 first-order U.S. National Weather Service stations scattered among six regions of Alaska to study the thermal history of the state over the period 1951-2001.

What was learned
The regional changes in mean annual air temperature from 1951 to 2001, based upon linear least squares regression analysis, were determined to be +1.9°C (South-Central), +1.6°C (West), +1.7°C (Interior), +0.8°C (Southwest), +1.3°C (Southeast) and +1.9°C (Arctic). However, and this is a really big "however," Hartmann and Wendler report that a significant amount of this warming was the result of a dramatic regime shift that occurred in 1976. Omitting that single year, for example, and looking at the two 25-year periods on both sides of the regime shift, they say that they "generally observe the opposite trend: cooling."

What it means
With respect to the temperature behavior of Alaska over the last half of the 20th century, the two researchers from the Geophysical Institute of the University of Alaska Fairbanks note that "a gradual increase might be expected from the observed steady increase of greenhouse gases" over that period. However, their results show something radically different: a general tendency for cooling over the 25 years preceding 1976, as well as a general tendency for cooling over the 25 years following 1976.

Clearly, Alaska is not the canary-in-the-coal-mine "poster child" for CO2-induced global warming that U.S. Senators John McCain and Hillary Clinton make it out to be (see our Editorial of 24 Aug 2005) or that former U.S. Vice President Al Gore claims it is (see his recent movie). Quite to the contrary, the state's climatic history is a testament to the incredible power of periodically-occurring climate regime shifts that rapidly heat and cool this and many other parts of the world without any regard to what the air's CO2 content may be doing.