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The polar bear faces possible extinction as global warming causes its Arctic sea-ice habitat to disappear. Polar bears are dependent on sea-ice for most all behaviors linked to their survival. Hunting, mating, travel and maternity denning all take place on the sea-ice. As global warming causes this unique habitat to literally melt away, scientists are recording data on polar bear populations that infer a decrease in number, a decrease in reproduction rates and a decrease in weights of individuals, especially females.

The polar bear is the largest of bear species and is highly adapted to life on the sea-ice. Its large size, its fur which is dense, water repellent and multilayered, and its thick layer of insulating fat are examples of adaptations to life in an arctic environment. Polar bears are so well insulated that they do not emit enough body heat to be detected by infrared photography. Unlike its omnivorous relatives the black bear and brown bear, the polar bear is strictly carnivorous and specializes in hunting seals, especially the ringed seal. Polar bears rarely capture their prey in open water, relying instead on the sea-ice as a hunting platform. The polar bear, top predator in its food chain, is a critical part of the Arctic ecosystem, often consuming only the skin and blubber of its prey, leaving the rest for scavengers. During the winter, Arctic Foxes feed almost exclusively on the remains of polar bear kills.

Polar bears have one of the slowest reproductive rates of any mammal, with females reaching sexual maturity late and having few and small litters. Polar bears mate on the sea-ice, and then females must accumulate a sufficient amount of fat to survive a winter in the maternity den. Cubs are very much dependent on maternal care when they emerge from their den in the spring. From birth to weaning, the reproductive cycle takes approximately three years.
Recovery from a population decrease is made difficult by such a slow rate of reproduction.

Polar bears range throughout the ice-covered waters of the circumpolar Arctic. Temperatures are rising more rapidly in the Arctic than in the rest of the world causing the speedy disappearance of the sea-ice habitat. Some scientists predict the ice will be completely melted by 2040. Polar bears could gain the distinction of being the first mammals in the world to lose 100 percent of their habitat due to global warming.

The Center for Biological Diversity filed a scientific petition with the U.S. Fish and Wildlife

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