The U.S. Department of Interior's decision to list the polar bear as a threatened species rests upon several models, which have projected a downward trend in polar bear populations over the coming years. These models are based upon historical figures of polar bear populations and changes in arctic ice levels.
In a recent National Review article, Roy Spencer, principal research scientist at the University of Alabama in Huntsville, criticizes the nine U.S. Geological Surveys, upon which the Interior Department relied in the listing decision. Spencer indicates that "those unpublished USGS studies did not follow accepted principles of scientific forecasting." Spencer suggests that a more credible forecast for the polar bear population is "Polar Bear Population Forecasts: A Public Policy Forecasting Audit," authored by Scott Armstrong, Kesten Green, and Willie Soon. Evidently this is the only peer-reviewed paper addressing the forecasting of polar bear population at this time.
Spencer also questions why the Department of Interior is willing to rely upon studies that are not peer-reviewed and points out that the U.N.’s Intergovernmental Panel on Climate Change (IPCC) explicitly requires that studies on global warming be "peer reviewed and published" to ensure legitimacy.
He argues that polar bear populations remain healthy and points out that the polar bear population has risen dramatically since 1950. In fact, Spencer states that "the total polar bear population is believed to be at or near a record high — 20,000 to 25,000." Only two of 13 polar bear subpopulations have shown signs of decline in recent years, while "the remaining eleven subpopulations have been stable or growing."