Polar bears were added to the list of threatened species and will receive special protection under U.S. law. In his statement, Secretary of the Interior Dirk Kempthorne noted that the decline of Arctic sea ice is the greatest threat to the bears.
Polar bears live in the Arctic and hunt seals and other fatty marine mammals from sea ice. They also travel, mate, and sometimes give birth on the ice. But sea ice is melting as the planet warms, and it is predicted to continue to do so for several more decades.
"Because polar bears are vulnerable to this loss of habitat, they are—in my judgment—likely to become endangered in the foreseeable future," Kempthorne said.
Although many scientists say that human activity is directly responsible for the melting sea ice, the new polar bear protections will not change U.S. climate policy.
The U.S. classifies the polar bear as a marine mammal, which means that the bear's new threatened status will not stop oil exploration within its habitat. Hunting of polar bears as a food source by certain native people and trade in native handicrafts made from polar bears will also continue. However, importing polar bear products from Canada (where trophy hunting is legal) will be banned.
Scott Bergen is a landscape ecologist with the New York-based Wildlife Conservation Society and a contributing author to U.S. Geological Survey studies released in 2007 that found two-thirds of the world's polar bears could go extinct by 2050. He and other WCS staff are "almost elated" with the decision, he said.
"Even though it doesn't directly influence carbon emissions so to speak, we think it is a definite decision in the right direction and we're pleased to see the Fish and Wildlife Service is supporting the best science on this species," he added.
Bergen noted that saving the polar bear will depend on international cooperation. Permanent sea-ice habitat is likely to remain in areas outside of the U.S., particularly in Canada and Greenland.
Scientists view these areas as refuges that could allow some polar bear populations to survive over the long term and repopulate the Arctic if temperatures decrease and sea ice returns.
"If you take a long-term view—meaning a hundred-year view into the future," he said, "polar bears' existence is not necessarily totally dependent on what happens in the United States."