Polar bears have recently become a synonym for global warming. These big bears that live in Arctic are recently experiencing big decline in population mostly because of global warming, and in 2008 polar bears were finally listed threatened species under the Endangered Species Act. Global warming is problem No.1 for polar bear population because increased temperatures melt ice, reducing more and more of their habitat, making it far more difficult for them to find enough food to survive.
In the past hunting was main reason of concern for polar bear population future but now polar bears have to overcome even bigger challenge to survive, challenge in form of man-made global warming. According to IUCN "if climatic trends continue polar bears may become extirpated from most of their range within 100 years". It is difficult to tell exact numbers of polar bears today, but many estimates predict total polar bear population of somewhere between 20,000-25,000.
Polar bear is the largest carnivore that lives on the land. The largest polar bear on record was reportedly weighing 1,002 kg (2,210 lb). Despite their gigantic size polar bears are excellent swimmers, and pretty good runners (as fast as 40 kph-25 mph for short distances). These are great advantages in hunting their prey, mostly seals. However, if global warming continues all these advantages might become useless because polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt significantly earlier in the year, driving the bears to shore before they have built enough fat reserves to survive the period of scarce food in the late summer and early fall. And less ice cover also means that polar bears have to swim much further to catch seals, where they use lot of energy, and sometimes even leads to drowning (4 cases were registered in 2008).
Changes in sea ice also have significant effect on polar bear reproduction, and affect the ability of pregnant females to build suitable maternity dens since females must swim much longer distances to reach favored denning areas on land. Thawing of permafrost would affect the bears that traditionally den underground, and warm winters could result in den roofs collapsing, resulting in loss of many polar bear cubs.
Global warming and polar bear are extremely closely connected. If we for instance look at the he Western Hudson Bay population, we can see that due to earlier ice-floe breakup (it occurs three weeks earlier than 30 years ago) polar bear feeding season is significantly reduced, which resulted in not only big decline in population (by more than 20 % in the last 30 years), but also in smaller average size. The average weight of lone (and likely pregnant) female polar bears was approximately 290 kg (640 lb) in 1980 compared to only 230 kg (510 lb) in 2004. Situation isn't much better in Alaska either, where the effects of sea ice shrinkage have contributed to higher mortality rates in polar bear cubs, and have led to changes in the denning locations of pregnant females.
Despite being listed on Endangered Species List U.S. is still not doing enough to protect remaining polar bear population. Even president Obama who promised environmental miracles is slowly but surely turning more into a politician than the actual environmentalist. This has been confirmed with the latest move by Obama administration where they decide to stick with a Bush-era policy against expanding protection for climate-threatened polar bears. They have of course politically explained this decision by saying: "we must do all we can to protect the polar bear but using the species protection law is not the right way to go."
Politics at its very best. Administration that really cares about environment should use all that is at their arsenal to fight climate change, and Endangered Species Act is one of the best weapons they have. But there are certain other interests involved in the whole story, most notably different oil and gas development projects in Alaska. After all profits are much more important to politics than polar bears and climate change.