evidence: Polar bear: A polar bear is fit to swim 100 miles for food, in search of mates or, more recently, just some ice to stand on. With five inches of blubber keeping this enormous bear prepared for subzero temperatures, the largest member of the bear family has adapted to remarkable Arctic conditions. The fat stored in a polar bear carcass becomes essential food for other Arctic species, like the Arctic fox. However, the extreme impacts that human-caused climate change has had on the Arctic is pushing the polar bear closer to extinction. [...] Listed as a "threatened" species in 2008, polar bears are rapidly losing the sea ice they use to hunt, mate and raise their young. Polar bear numbers increased following the establishment of hunting regulations in the 1970s and today stand at 20,000 to 25,000. However, the rapid decline of Arctic sea ice because of global warming has reversed this trend, and currently at least five of the 19 polar bear populations are declining. The U.S. Geological Survey predicts that under current greenhouse gas emission trends, two-thirds of the world’s polar bears, including all those in Alaska, will likely disappear by 2050.