Biologist Steven Amstrup discusses global warming, polar bears in Oregon Zoo lecture
Scientists agree: If greenhouse-gas emissions remain uncurbed, the consequences to the planet will be devastating. Wildlife biologist Steven Amstrup discusses the effects of global warming on polar bears as part of the Wildlife Conservation Lecture Series on Tuesday, Feb. 27, at the Oregon Zoo.
Amstrup, a research wildlife biologist with the Alaska Science Center, is an expert on polar bears and has studied firsthand the effects that the changing climate is having on their population. Amstrup presents his findings during the lecture "Polar Bear: Ultimate Sentinel for Climate Change."
"Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales and other aquatic animals," says Amstrup. "But because polar bears are not aquatic, their only access to the seals is from the surface of the sea ice."
Over the past 25 years, the summer sea-ice melt period has lengthened, and the summer sea-ice cover has declined by more than a half million square miles. "Longer ice-free seasons have resulted in reduced survival of young and old polar bears and a chronic population decline over the past 20 years," says Amstrup.
"Recent observations of nutritionally driven cannibalism and unexpected mortalities of prime age polar bears in Alaska are