New York Times: Grim Outlook for Polar Bears

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Grim Outlook for Polar Bears
By ANDREW C. REVKIN

ANCHORAGE — Two biologists who measure field time with polar bears in decades sat in a federal building here, envisioning two possible fates for this denizen of ice in a warming world — and neither future looked bright.

A polar bear expert with the Fish and Wildlife Service, Scott L. Schliebe, said the bears were resilient and adaptable, but just to a point. “I truly believe this is an important part of our natural history,” Dr. Schliebe said. “We should take every effort we can to try to maintain it.”

On one possible track, the bears, facing a chronic food gap, could weaken and reproduce ever less as the ice-free summer season expands. The other course could be a swift collapse, should more summers unfold like this past one, said Steven C. Amstrup of the United States Geological Survey. He led an exhaustive recent study of polar bears in a federal review weighing whether they should be put on the endangered species list.

If emissions of greenhouse gases and resulting global and Arctic warming continue apace, the study said, two-thirds of the 22,000 or so bears will disappear by midcentury. Some bear experts see that prognosis as overly dire.

The script for a slow fade-out may already be on display along the western shores of Hudson Bay in northern Canada, Dr. Amstrup said.

After binging on ringed seals early each year, this southern population, well below of the Arctic Circle, leaves the melting ice and scrounges snow geese and lyme grass, losing weight all summer.

“It appears they’ve reached a point where the earlier departure of the sea ice and their earlier appearance onshore is starting to affect their survival,” he said.

But an abrupt collapse could occur, as well, Dr. Amstrup said.

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