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Interior Alaska Temperatures: Are They the Canary-in-the-Coal-Mine of CO2-Induced Global Warming?
Barber, V.A., Juday, G.P., Finney, B.P. and Wilmking, M. 2004. Reconstruction of summer temperatures in interior Alaska from tree-ring proxies: Evidence for changing synoptic climate regimes. Climatic Change 63: 91-120.

The authors note that "a robust result of General Circulation Model simulations is that high-latitude land masses in the northern hemisphere will experience the greatest magnitude of warming under scenarios of increased anthropogenically produced greenhouse gases (Houghton et al., 1996)." Because of this theoretical model-based result, they say "it is tempting to interpret recent warming and ecological changes in Alaska as evidence for the greenhouse gas - climate-warming theory," and indeed it is. In fact, the temptation has proven to be truly irresistible many times over to the world's climate alarmists, who repeatedly claim just that. Before such an attribution can validly be made, however, Barber et al. correctly state that "it is crucial to know whether other similar rapid climate changes and conditions occurred in the past," when anthropogenic-produced greenhouse gases were not a part of the picture.

What was done
To acquire this essential knowledge, the four Alaskan scientists used maximum latewood density and 13C discrimination measurements made on Interior Alaska white spruce to reconstruct summer (May-August) temperature for the period 1800-1996.

What was learned
The reconstructed temperature history was characterized by seven decadal-scale regimes, with abrupt shifts occurring at 1816, 1834, 1879, 1916, 1937 and 1974. Barber et al. additionally found that summer temperatures of the latter part of the 20th century were "characterized by some of the warmest summers in the 200-year interval." However, they note that mid-19th century summer temperatures also "reconstruct as some of the warmest over the 200-year period." In fact, they say that summer temperatures during two periods in the mid-1800s "are about as warm as present." Furthermore, they "show additional tree ring data that support [their] reconstruction of these warm periods."

What it means
Clearly, the recent warmth in Alaska is in no way unprecedented in either its degree or rate of development, having been replicated at least twice in the 19th century alone. Thus, it is truly disingenuous to claim, as climate alarmists typically do, that current Alaskan warmth is a product of anthropogenically-produced greenhouse gases. It just ain't so. Hence, current Alaskan warmth is also not the elusive canary-in-the-coal-mine that everyone is seeking but no one can seem to find. Maybe that's simply because there is no such bird.

Houghton, J.J., Meiro Filho, L.G., Callander, B.A., Harris, N., Kattenberg, A. and Maskell, K. (Eds.). 1996. The Science of Climate Change. Contribution of Working Group I to the Second Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), Vol. I. Climate Change 1995. Cambridge University Press, Cambridge, UK.

Reviewed 19 May 2004