Bear Facts
Climate Change
The Arctic's climate is changing, with a noticeable warming trend that is affecting polar bears. The region is experiencing the warmest air temperatures in four centuries. The Intergovernmental Panel on Climate Change, the U.S. EPA, and the Arctic Climate Impact Assessment all report on the effect of this climatic change on sea-ice patterns. A recent report notes that more than 20% of the sea ice in the Far North has disappeared over the past two decades. Scientists predict a mostly ice-free Arctic summer by 2040 if present trends continue. Many scientists believe that the Arctic will continue to grow warmer as a result of human activity, namely, the introduction into the atmosphere of increasing quantities of carbon dioxide and other greenhouse gases. Although the Arctic has experienced warm periods before, the present, rapid shrinking of the sea ice coverage in the Arctic is unprecedented.
Anecdotal evidence indicates that polar bears may be leaving the sea ice to den on land in winter. In Russia, large numbers of bears have been stranded on land by long summers that prevent the advance of the permanent ice pack. Some Inuit hunters in Canada say they can no longer hunt polar bears in the spring because of early ice melts. In the Western Hudson Bay area, permafrost has declined, leaving polar-bear denning areas susceptible to destruction by forest fires in the summer. A warm spring might also lead to increased rainfall, which can cause dens to collapse.
Polar bears depend on a frozen platform from which to hunt seals, the mainstay of their diet. Without ice, the bears are unable to reach their prey. A shorter hunting season has already adversely affected the polar bears of Western Hudson Bay (the population near Churchill in the Province of Manitoba, Canada). Scientists have documented a 22% drop in the Western Hudson Bay polar bear population since the early 1980s. The decline directly correlates with a longer ice-free season on the bay.
A new study of the Southern Beaufort Sea population, which is shared by the U.S. and Canada, has revealed a drop in cub survival rates as well as the weight and skull size of adult males, when compared with data collected 20 years ago. This is a cause for concern because such declines were observed in the Western Hudson Bay population before it dropped.
In a warming Arctic, the bears may not be able to swim the distances required to reach solid ice if reduced ice coverage leads to more open water. In 2004, four polar bears drowned off the coast of Alaska when trying to swim to the pack ice.
Because polar bears are a top predator in the Arctic, changes in their distribution or numbers could affect the entire Arctic ecosystem. There is little doubt that ice-dependent animals such as polar bears will be adversely affected by continued warming in the Arctic. It is therefore crucial that all factors which may affect the well-being of polar bears be carefully analyzed. Scientists believe that we have about 10 years in which it is still possible to reverse the effects of human-induced climate change.
Anecdotal evidence indicates that polar bears may be leaving the sea ice to den on land in winter. In Russia, large numbers of bears have been stranded on land by long summers that prevent the advance of the permanent ice pack. Some Inuit hunters in Canada say they can no longer hunt polar bears in the spring because of early ice melts. In the Western Hudson Bay area, permafrost has declined, leaving polar-bear denning areas susceptible to destruction by forest fires in the summer. A warm spring might also lead to increased rainfall, which can cause dens to collapse.
Polar bears depend on a frozen platform from which to hunt seals, the mainstay of their diet. Without ice, the bears are unable to reach their prey. A shorter hunting season has already adversely affected the polar bears of Western Hudson Bay (the population near Churchill in the Province of Manitoba, Canada). Scientists have documented a 22% drop in the Western Hudson Bay polar bear population since the early 1980s. The decline directly correlates with a longer ice-free season on the bay.
A new study of the Southern Beaufort Sea population, which is shared by the U.S. and Canada, has revealed a drop in cub survival rates as well as the weight and skull size of adult males, when compared with data collected 20 years ago. This is a cause for concern because such declines were observed in the Western Hudson Bay population before it dropped.
In a warming Arctic, the bears may not be able to swim the distances required to reach solid ice if reduced ice coverage leads to more open water. In 2004, four polar bears drowned off the coast of Alaska when trying to swim to the pack ice.
Because polar bears are a top predator in the Arctic, changes in their distribution or numbers could affect the entire Arctic ecosystem. There is little doubt that ice-dependent animals such as polar bears will be adversely affected by continued warming in the Arctic. It is therefore crucial that all factors which may affect the well-being of polar bears be carefully analyzed. Scientists believe that we have about 10 years in which it is still possible to reverse the effects of human-induced climate change.
Climate Change - Related Topics
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