Melting Arctic Sea Ice Threatens Polar Bears

By Crystal Davis on Monday, January 8, 2007.

Arctic perennial sea ice is disappearing at a rate of nearly nine percent per decade as a result of global warming. If this trend continues, summer ice could be completely melted as early as 2040, meaning that arctic ice would no longer be a year-long phenomenon. The implications of this loss could be devastating for polar bears, which rely on ice floes for shelter, hunting and breeding. In response, the Bush administration recently announced a proposal to list polar bears as a "threatened" species under the Endangered Species Act.

Extent of September Sea Ice

Source: The National Snow and Ice Data Center

Threats to Polar Bears
Polar bears are threatened by oil and gas exploration, pollution, overhunting, development, and even tourism. Global warming, however, presents the most serious risk to the estimated 20,000 polar bears existing in the wild. In the bear's southernmost habitat, summer ice is melting earlier and returning later, which has substantially reduced hunting opportunities. Scientists have documented significant weight loss and a 15 percent drop in birth rates among bears in these regions. Researchers have also documented multiple drowning deaths of polar bears swimming long distances in search of the receding Arctic ice shelf. As warming increases these trends will likely spread to the northernmost populations.

Projected Changes in Arctic Ice Pack

Map Designer: Hugo Ahlenius, UNEP/GRID-Arendal

Government Action
Interior secretary Dirk Kempthorne's proposal to list polar bears as a "threatened" species was a response to legal pressure from several environmental groups: the Center for Biological Diversity, the Natural Resources Defense Council, and Greenpeace. If the proposal is accepted, federal agencies must ensure that government actions do not jeopardize polar bears or their habitat. This could include decisions related to cutting back greenhouse gas emissions and other actions to combat global warming.

Distribution of Polar Bear Populations in the Arctic

Map Designer: Philippe Rekacewicz, UNEP/GRID-Arendal

Polar bears are not the only species threatened by global warming. A major international study published in the peer-reviewed journal Nature found that 15 to 35 percent of species worldwide may be at risk of extinction by 2050. The survival of these species will depend in part on the climate change policies adopted by the world's largest greenhouse gas emitters.