Polar bears (Ursus maritimus) are marine mammals found throughout ice-covered seas in the Northern Hemisphere that live on sea ice but spend significant time on land and have endured through previous periods of global warming. In the late 1960s, some 8,000-10,000 polar bears were known to exist, but today there are 20,000-25,000 polar bears worldwide. In the last few years, the worldwide population has not declined significantly.
Nonetheless, in response to a petition by the Center for Biological Diversity to list the polar bear under the ESA, the FWS, in January 2007, published a finding that listing of the polar bear was warranted and a draft rule to list the polar bear as "threatened." In May 2008, the Secretary of Interior published both a final rule determining polar bears to be threatened and regulations to protect the polar bear.
The FWS opined that polar bear habitat—sea ice—is declining over the species' range, that this decline is expected to continue for the foreseeable future, and that this loss threatens the species throughout all of its range. According to the FWS, productivity, abundance, and availability of ice seals—the polar bear's primary prey—will be diminished by the loss of sea ice and polar bears will be required to expend more energy to obtain food. The FWS concluded that existing regulations are inadequate because they were not effective in "counteracting the worldwide growth of" greenhouse gasses.