Monday, January 01, 2007

On the Polar Bear Listing

The age structure and survivorship patterns of recent years suggest the population in the Beaufort Sea may be at or near the limits set by its environment.
Unfortunately, known and unknown biases in our mark and recapture data resulted in population size estimates that were associated with considerable uncertainty. The degree of fluctuation we observed in population estimates derived by the sophisticated Jolly-Seber model were biologically impossible. The estimates were more consistent in the simpler Petersen model, substantiating the observation that the trend of increase is valid, but not erasing concerns about the absolute size of the population.(Amstrup 1992)


I use denning data in Warm Front from Dr. Amstrup of the Alaska USGS Office. As he says here reliable numbers are difficult to determine, and this is only for the Beafort Sea population. The proposed listing doesn't say they are declining now, but the shrinking icepack, evidence of drownings, and emaciation observed firsthand indicate a future trend of decline based on the models of the icepack and increasing global mean temperatures, which are magnified at the poles. Never fear though, because the opinion writers have been dispatched from Wingerville Central to the Washington Times by Pete du Pont to dispel realty. Context is not on their side and the governments of two countries in North America don't agree. Why would that be?

Polar bears and the seals on which they prey may also be among the first species to show effects of climate warming and other global changes (Stirling and Derocher 1993).

The latest research by Dr. Steven Amstrup as of last year and ongoing confirms this prediction and trend.

When Hudson Bay is ice-free, polar bears remain on land where they make little use of terrestrial food sources. In the past 30 years rising temperatures have increased the duration of the ice-free period and the polar bear's seasonal fast by more than two weeks. Although the resulting nutritional stress has been correlated with downward trends in body condition and recruitment, this study was the first to provide evidence of a population-level effect of climatic warming on polar bears.

I suppose leaving this sort of scientific prediction out based on admitted numbers is tried and true for the business propagandists. This aspect is a key component in the plot of my novel. And the novel has a real scientific literature bibliography.

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