Are Polar Bears Threatened By Climate Change?
As with most everything involving climate change, data are limited and studies are contradictory. Satellite imaging has only allowed accurate measurement from about 1979—a short span of time to use in extrapolating forward. The Intergovernmental Panel on Climate Change (IPCC) summarizes Arctic ice changes in its most recent report: “Satellite data indicate a continuation of the 2.7 ± 0.6% per decade decline in annual mean Arctic sea ice extent since 1978. The decline for summer extent is larger than for winter, with the summer minimum declining at a rate of 7.4 ± 2.4% per decade since 1979. Other data indicate that the summer decline began around 1970.” The IPCC computer models project that Arctic ice decline will continue into the future. But the IPCC projections are based on the assumption that Arctic ice melting is the result of global warming caused by greenhouse gas emissions, and that remains a questionable assumption. In a January 2008 publication in Nature (hardly a hotbed of c
