Basis a novel insight, scientists are positive about the adverse impact of climatic change on polar bear populations.
The research, by a team of scientists from the U.S. Geological Survey (USGS), Woods Hole Oceanographic Institution (WHOI), University of Alaska, University of Maryland, Canadian Wildlife Service and the US Forest Service, refutes point-by-point a widely publicized critique of polar bear population predictions.
The new rebuttal reinforces the reports written by the scientists and accepted by the Department of Interior in its May 2008 decision to list polar bears as a threatened species on the U.S. Endangered Species Act.
"The decision to list the polar bear as threatened was politically charged, and the scientific research on which it was based attracted some criticisms," said WHOI biologist Hal Caswell, an author on two of the USGS reports and of the rebuttal.
"Our new study shows that the critique is incorrect and based on misconceptions about climate models, the Arctic environment, polar bear biology, and statistical and mathematical methods," he added.
The rebuttal was published in the journal Interfaces online on April 22, 2009, and will be published in the July-August print edition.
In 2007, when the Department of the Interior was considering listing the polar bear under the Endangered Species Act, it asked the USGS to assemble an international team to analyze information on polar bear populations.
The team estimated the probabilities of future polar bear population growth or decline.
The USGS-led group presented its reports in fall 2007, and in May 2008, the Department of Interior listed the polar bear as a threatened species under the US Endangered Species Act.
Following that listing, a critique of the USGS reports was published in the Sept.-Oct. 2008 issue of the journal Interfaces.
"After going through their report, however, we decided we needed to do a rebuttal of this, and in the end, we went point by point to refute their criticism," said Caswell.
According to Caswell, "We began by explaining why the sea ice habitat of polar bears is declining and showing how climate models, outputs from which we used as inputs to our analyses, are reliable for forecasting the future climate."
"Finally, we took a look at their principles of forecasting, and found they are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations," he said.