Two of the best papers that go directly to the heart of the issues on the polar bear listing as endangered by the US government are:

Demographic and Ecological Perspectives on the Status of Polar Bears, by Dr Mitchell Taylor and Dr Martha Dowsley, March 2008,
http://scienceandpublicpolicy.org/originals/demographic_and_ecological_polar_bear_perspectives.html

Taylor and Dowsley are world class.

Polar Bear Population Forecasts: A Public-Policy Forecasting Audit (Working Paper Version 75), by
J. Scott Armstrong, Kesten C. Green, and Willie Soon, April 2008,
http://www.forecastingprinciples.com/Public_Policy/polarbear.html

Armstrong literally wrote the book on forecasting principles.

Robert Ferguson
President, Science and Public Policy Institute