Wired Science has an article pointing to some recent findings about both genetic evidence that polar bears have been around longer than we had thought, and that they have adapted quickly in the past to changes in climatic conditions.

DNA Analysis Shows Polar Bears Have Adapted Quickly in the Past

Genetic analysis of an ancient polar bear fossil has formally dated the species’ birth to 150,000 years ago, shortly before an Ice Age thaw produced a climate comparable to what’s expected in a globally warmed future.

“They’ve certainly experienced climate changes before,” said Charlotte Lindqvist, a biologist at the State University of New York at Buffalo and co-author of the analysis, published March 1 in the Proceedings of the National Academy of Sciences. “The big question is whether they’re going to be able to survive in the future.”

They're still talking about tens of thousands of years, not decades - but there is hope

This is a grizzly Bear (Ursus arctos), photographed in Wapusk National Park,

Manitoba, Canada, on August 9, 2008. (Credit: Linda Gormezano)

ScienceDaily (Feb. 23, 2010) — Biologists affiliated with the American Museum of Natural History and City College of the City University of New York have found that grizzly bears are roaming into what was traditionally thought of as polar bear habitat -- and into the Canadian province of Manitoba, where they are officially listed as extirpated. The preliminary data was recently published in Canadian Field Naturalist and shows that sightings of Ursus arctos horribilis in Canada's Wapusk National Park are recent and appear to be increasing in frequency.

"Grizzly bears are a new guy on the scene, competition and a potential predator for the polar bears that live in this area," says Robert F. Rockwell, a research associate at the Museum and a professor of Biology at CUNY. "The first time we saw a grizzly we were flying over the middle of Wapusk, counting fox dens, when all of the sudden Linda Gormezano, a graduate student working with Rockwell and a co-author of the paper, shouted 'Over there, over there -- a grizzly bear.' And it wasn't a dirty polar bear or a moose -- we saw the hump."

That sighting in August 2008 spurred Rockwell and Gormezano to look through records to get a better picture of the bear population in the park. There was no evidence of grizzly bears before 1996, not even in the trapping data from centuries of Hudson Bay Company operation. But between 1996 and 2008 the team found nine confirmed sightings of grizzly bears, and in the summer of 2009 there were three additional observations. ...

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 Grizzly Bears move in to Polar Bear habitat

ScienceDaily (Feb. 26, 2010) — A joint Australian-French study has discovered the calving of a large iceberg from the Mertz Glacier in the Australian Antarctic Territory. The iceberg -- 78 kilometres long with a surface area of roughly 2,500 square kilometres, about the size of Luxembourg -- broke off the Mertz Glacier after being rammed by another iceberg, 97 kilometres long.

The study, undertaken at the Antarctic Climate and Ecosystems Cooperative Research Centre (ACECRC) in Hobart, and in France, was initiated in 2007 during the International Polar Year to study the 'tongue' of the Mertz Glacier and the 'calving' of icebergs from it.

The Mertz Glacier had a large crack in it for two decades. A second crack developed opposite the first in the early part of the 21st century. The collaboration studied whether these two cracks would eventually meet, and the processes that would lead to the calving of an iceberg.

Background

The joint French-Australian team that detected this calving event has been working on a project called "CRACICE" (Cooperative Research into Antarctic Calving and Iceberg Evolution). The iceberg has an area of about 2,550 square kilometers, an overall length of 78 kilometers, width of 33 to 39 km, and represents about half the length of the glacier tongue. Satellite imagery shows the iceberg separation occurred on February 12-13.

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 Iceberg breaks off Mertz Glacier