The Heat Is On
The Bush administration has an important decision to make by Thursday. It must decide whether polar bears deserve protection under the Endangered Species Act.
The U.S. Fish and Wildlife Service has asked that polar bears be listed as endangered because global warming is affecting their habitat. But some businesses are against the proposal because of how it might affect their future operations.
Polar bears are almost completely dependent on Arctic sea ice for survival. They use the ice as a platform from which to hunt and feed on seals, to seek mates and to travel long distances. However, the annual sea ice in the Arctic is now melting earlier in the spring and forming later in the fall.
Why Does This Matter?
Polar bears, the world's largest land carnivores, have no natural enemies. Their diet consists mostly of ringed and bearded seals. Rifts in the ice, called leads, act as breathing holes for seals. A polar bear will crouch near such a hole and wait patiently -- from hours to days -- for a seal to surface. When it does, the bear will reach into the hole with a forepaw and drag the seal out onto the ice to attack it.
As the southern edge of the Arctic ice cap melts in the summer, most polar bears move north with the retreating sea ice to continue their hunting. Some bears get stranded on land and spend their summers living off body fat stored from hunting in the spring and winter.
Higher annual temperatures, which scientists say are likely caused by greenhouse gases, are shrinking this ice that the bears depend on for survival.
How Serious Is the Problem?
Using satellite images, the National Snow and Ice Data Center in Boulder, Colorado, estimates that the Artic ice cap has shrunk by one-fifth since 1979. The U.S. Department of the Interior reports a decline in late-summer Arctic sea ice by as much as 7.7 percent per decade since 1978. Scientific observations in some areas also have shown a thinning of the ice by almost a third from the 1960s to the 1990s.
All of these changes leave polar bears with less time on the sea ice to hunt for food and build up their fat stores. When they spend more time on land, where hunting is not possible, polar bears end up eating less. The reduction in sea ice also forces bears to swim longer distances, which further depletes their stored energy.
The number of polar bears worldwide is estimated at 20,000 to 25,000. The U.S. Geological Survey predicts that two-thirds of the population could vanish with the melting habitat by 2050.
What a Change Would Mean
Only two species -- elkhorn coral and staghorn coral in the Caribbean Sea -- have gotten Endangered Species Act protection because of global warming.
In theory, a listing for the polar bear could trigger a plan with wide-reaching consequences.
Opponents say that protecting polar bears could block new oil and gas drilling in one of the prime polar bear habitats in the Chukchi Sea off Alaska. Others say that proposed coal-fired power plants, which would be used to meet the United States' growing energy needs, would not be built.
-- Brenna Maloney