Wildlife on the Brink: Polar Bear

SCIENTIFIC NAME: Ursus maritimus

STATUS: Proposed for threatened status

HABITAT: Primarily coastal sea ice

LIFE HISTORY: One of the lowest reproduction rates among mammals; females rear cubs for three years. Bears roam an average of 5,500 miles annually.

THREATS: Habitat loss due to global warming

RANGE: Circumpolar

CURRENT POPULATION: 2,000 to 3,000 in U.S.; global population 20,000 to 25,000

The polar bear's Arctic home was once hardly touched by humans, but now their habitat has become a striking indicator of global warming.

These beautiful, massive bears are strong swimmers, but they need terra firma (in the form of sheets of sea ice) on which to hunt seals, sleep and find mates. If Arctic sea ice continues to shrink—and scientists predict that Arctic summers could be virtually ice-free by 2050—polar bears might have to spend more time and energy in the water, swimming. Warm spells could make it harder to find a good spot to build a den, and hunting could be more difficult if climate change affects populations of favored prey, such as ringed seals.

In response to a petition and lawsuit filed by NRDC, the Center for Biological Diversity, and other groups, the federal government has formally proposed listing the polar bear as a "threatened" with extinction under the Endangered Species Act. NRDC members and other concerned activists have submitted more than 300,000 comments in support of the proposal. The administration will make a final decision by January 2008.

Photo: polar bear © Steve Amstrup, Alaska Image Library, USFWS