Tom Kizzia reports on new US Geological Survey research concluding that global warming and sea ice retreat are dooming Alaska's polar bear populations: Alaska polar bears called doomed (Anchorage Daily News, September 8):
Polar bears will be gone from Alaska within 50 years, government scientists predicted Friday.
Shrinking sea ice will leave only a remnant surviving population of the world's polar bears in the islands of the Canadian Arctic by mid-century, according to a breathtaking new study by the U.S. Geological Survey. Two-thirds of the world's polar bears, including those along the coasts of Alaska and Russia, will have disappeared.
The loss of summer sea-ice habitat will be so profound for bear populations that regional efforts to protect them, such as restricting subsistence hunting or Arctic oil and gas development, will not be able to prevent their disappearance, the government scientists said.
Moreover, the bears' doom is irreversible, the study said....
The new set of USGS studies, provided to Congress Friday, were undertaken to aid Interior Secretary Dirk Kempthorne's decision whether to designate polar bears a "threatened" species under the Endangered Species Act. A decision is due by next January.
The State of Alaska, fearing consequences for subsistence hunting and oil production, has strenuously opposed a federal threatened-species listing, arguing, among other things, that bear populations have been stable and that too much uncertainty surrounds projections of global warming trends.
The new study notes that more polar bears are likely to be seen on land as the ice melts, increasing contact with humans in the short term.
Scientists think there are 20,000 to 25,000 polar bears in the world. One-fifth or so live in Alaska and nearby on the coast of the Beaufort and Chukchi seas.
The bears are considered marine mammals because they depend on sea ice for hunting their prey: seals breathing through holes or along the edges of open-water leads....
While older bears will probably scrape along, scientists expect to see cubs and young adults die off and reproduction rates decline. Already, studies have reported shrinking weight and rising mortality of cubs. There have also been reports of polar bears drowning....
Amstrup rebutted the idea that polar bears could survive by adapting to land-based hunting. He said studies have shown the bears to be very inefficient hunters of land animals, which in any case do not provide the kind of rich nutrition polar bears seek.
He said the fossil record of polar bears goes back no more than 50,000 years, meaning they would not have had to adapt in the past to any period warmer than the present. If the bears go back more than 200,000 years, however -- and there is some genetic evidence of this, Amstrup said -- then they may have found a way in the past to adapt to an even warmer spell.
Here's the page with the USGS studies: New Polar Bear Finding. Ringed seals, an important polar bear prey, are also in trouble: Problems for ringed seals (Ben Muse, February 27, 2007). As are walrus: Bad news for walruses (Ben Muse, February 25, 2007).