In places like Hudson bay, there is no ice during the summer, so polar bears there have to stay on land to wait for the ice to freeze in the fall. During this fasting time, they metabolise their fat and protein stores and recycle metabolic by-products, resulting in a form of hibernation. In just 20 years, the ice-free period in Hudson bay has increased by 20 days, cutting short the polar bears’ hunting seasons for almost three weeks. It gets better for them when the ice starts to freeze in the fall, but it is the spring ice melt that is especially hard for the bears. As the ice-free period gets extended, the polar bears have a narrower time frame to hunt in the critical season when seal pups are born. As a result, average bear weight have dramatically dropped more than 15 percent, causing reproduction rates to decline.
Scarcity of food
Recent studies by biologists show that the declining habitat of polar bears may also be affecting one of the polar bears’ main prey --- seals. The dramatic reduction in ice platforms near productive areas for the fish that the seals eat affects their nutritional status and reproduction rates too. Reports also show that some starving polar bears have decided to take on cannibalistic behavior, devouring other starving polar bears to revive themselves. Although it has long been known polar bears will kill for dominance or kill cubs so they can breed with the female, outright predation for food was previously unobserved by biologists.
Retreating ice platforms
The retreat of ice in the last few years was astronomical; it was beyond the obvious habitat loss. Remaining ice was farther away from shore, making it harder for the polar bears to reach and use. The larger gap of open water between ice caps and solid land also results in rougher wave conditions, making the bears’ swim from shore to sea ice more hazardous. In 2004, biologists discovered four drowned polar bears in the Beaufort Sea, and suspect the actual number of drowned bears may have been considerably greater. If this horrifying report keeps on continuing, how much polar bears will be drowned or starved in future years?
In conclusion, the polar bears are at high risk of being endangered, or even extinct. Their habitat is being destroyed by global warming, scarcity of food is forcing them to extremes, and melting ice caps is drowning even their best swimmers. Polar bears are like the proverbial "canary in the coal mine" of the serious threat global warming poses to animal and plant species around the world. In my opinion, the reason why global warming cannot be cured is because not everybody cares or helps; so if everyone puts a hand in to end global warming, not only us, but all organisms in the world will be able to leave this burden behind and live in a cleaner world.