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

What was done
The author reviews what is known about the evolution of climate and permafrost in Alaska over the past three decades.

What was learned
Osterkamp reports that "permafrost warmed at most sites north of the Brooks Range from the Chukchi Sea to the Alaska-Canada border, south along a transect from Prudhoe Bay to Gulkana and at sites up to 300 km from the transect," noting that "the warming was coincident with the statewide warming of air temperatures that began in 1976/1977," the magnitude of which "was 3 to 4C for the Arctic Coastal Plain, 1 to 2C for the Brooks Range including its northern and southern foothills, and 0.3 to 1C south of the Yukon River." However, this warming, in the words of Osterkamp, "was seasonal (primarily in winter) with little change in summer conditions." Consequently, and most importantly, Osterkamp states that permafrost "active layer thicknesses did not [our italics] increase and were not [our italics] correlated with warming permafrost conditions."

What it means
The active layer of the ground is the layer that freezes and thaws annually; and climate alarmists have been vociferous in warning about what is happening to it in Alaska as a result of what they describe as unprecedented warming in high northern latitudes over the past three decades. However, and as dramatic as the observed increases in Alaskan temperatures were over the this period, it would appear that the nature of the warming experienced throughout much of the state - an "almost step-like" increase in the vicinity of 1976/1977 that was confined almost exclusively to winter - combined with the fact that "active layer thicknesses," as Osterkamp states, "do not reflect warming conditions when the warming occurs primarily in winter" - has resulted in there being little to no warming-induced impact on the all-important thickness of the region's active permafrost layer.

Reviewed 24 October 2007