Wolfgang, the problem with polar bears is their dependence on sea ice and oceanic mammals (seals, mostly). At present, the polar bear population is for the most part stable, although several populations have gotten smaller. However, if much more warming occurs, these populations could fall catastrophically in a very short time.

When you look for warming information about the Arctic, you get mainly two stories: the story from organisations who pooh-pooh global warming, and cite temperature readings from Greenland, and the story from Arctic dwelling people, who can see with their own eyes what is happening in Nunavut, the Yukon and Alaska.

Last year, hunters killed a bear which turned out to be an anomaly: a grizzly-polar bear hybrid. Hybridization in the wild can be a sign of a species under stress (not necessarily in this case, but it is worrying). It has been documented with various dolphin and whale species, and with wolves (Eastern Canadian coyote populations are believed to be a well established wolf-coyote hybrid, called Brush Wolves in some locales).