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Late 20th-Century Thawing of Alaskan Permafrost
Reference
Osterkamp, T.E. 2007. Causes of warming and thawing permafrost in Alaska. EOS, Transactions, American Geophysical Union 88: 522-523.

What was done
The author "reviews the warming of permafrost in Alaska during the twentieth century," concentrating on the role played by snow cover, particularly over the last two decades.

What was learned
Osterkamp reports that for Barrow, for the period 1977-1998, "about one half of the permafrost warming for that period was a result of increased air temperatures while the other half [was] attributable to increased snow cover thicknesses (Stieglitz et al., 2003)." In addition, for Healy in interior Alaska, he notes that "the 1990s was a period of increased snow depths, and that snow cover effects during this period "were almost entirely responsible for warming and thawing permafrost at Healy," while noting that similar snow conditions during this period were observed "throughout Alaska."

What it means
The University of Alaska researcher says "there is a perception that climatic warming was the cause of the twentieth-century global warming and thawing of permafrost and associated terrain instability," citing Gore (2006). However, he notes that "published results do not support this viewpoint," citing Zhang et al. (2001) and Osterkamp (2007). Consequently, after presenting the new data from Healy described in his EOS report, which appear to be characteristic of much of the state, Osterkamp concludes that, in reality, "snow cover has played a significant role in it," ranging from being responsible for "about one half" of the recent permafrost thawing to being "almost entirely responsible" for it.

References
Gore, A. 2006. An Inconvenient Truth. Rodale Press, New York, New York, USA.

Osterkamp, T.E. 2007. Characteristics of the recent warming of permafrost in Alaska. Journal of Geophysical Research 112: 10.1029/2006JF000578.

Stieglitz, M., Dery, S.J., Romanovsky, V.E. and Osterkamp, T.E. 2003. The role of snow cover in the warming of Arctic permafrost. Geophysical Research Letters 30: 10.1029/2003GL017337.

Zhang, T., Barry, R.G., Gilichinsky, D., Bykhovets, S.S. and Sorokovifov, V.A. 2001. An amplified signal of climatic change in soil temperatures during the last century at Irkutsk, Russia. Climatic Change 49: 41-76.

Reviewed 6 February 2008