Among polar bear experts and climate scientists, the move has near unanimous support and is the first time the administration identified climate change as the main threat to a species’ potential extinction.
“As the sea ice disappears, we very much believe that the polar bears will disappear,” said Andrew Derocher, who chairs the International Union for Conservation of Nature and Natural Resources’ Polar Bear Specialist Group and is a professor at the University of Alberta. “Polar bears are a highly specialized carnivore that has adapted an Arctic marine lifestyle. Expecting them to turn around a hundred thousand years of evolution in a hundred years is not realistic.”
Global warming, scientists have concluded, is causing Arctic sea ice to melt earlier in the spring and freeze later in the fall, disrupting the polar bears’ habitat. Polar bears are the largest land predator and perched at the top of the food chain, they use the sea ice as a platform for hunting seals, traveling, mating and denning.
Over the last several decades, scientists have observed a 7.7 percent decline per decade of the Arctic’s sea ice in late summer and a 9.8 percent decline per decade in the perennial sea ice area. Polar bears do most of their feeding — primarily on ringed seals — from March to June and as the sea ice melts, this window of time is becoming shorter.
Scientists have observed recent indications of stress among some polar bear populations as a result of depleting sea ice and longer periods without access to food.
The first sign is a decline in body condition as the polar bears find it harder to find food. In turn, reproductive rates decrease and the survival rate of pups drops. The polar bear population in Canada’s Western Hudson Bay was the first to suffer the impacts of climate change, and scientists have documented a 22 percent decline in the area’s polar bear population. Scientists identified this pattern in populations of southern Hudson Bay and the southern Beaufort Sea and suspect it is occurring in other areas.
Among some populations, polar bears are resorting to unusual tactics to survive.
In the Alaskan polar bear population in the Beaufort Sea, polar bears have attempted to swim the distance between ice and land — gaps that are widening as the ice melts more — causing some to drown. Other bears driven by hunger have resorted to cannibalism.
The proposal to list polar bears as “threatened” came as part of a settlement with the Center for Biological Diversity, the Natural Resource Defense Council and Greenpeace, three conservation groups that sued the U.S. government in December 2005 for failing to protect the polar bear.
The three groups hope to use the listing as an opportunity to force the Bush administration to respond further to greenhouse gas emissions that cause global warming.
“The plight of the polar bear has become a phenomenon in the past couple of years,” said Kassie Siegel at the Center for Biological Diversity. “Keeping the polar bears in the news is useful in climate policy.”
But using the polar bear as the face of global warming could distract from the larger issue, some say.
“Polar bears are a charismatic species. That’s a double-edged sword,” said Brendan Kelley, the associate vice president for research at the University of Alaska and the National Science Foundation’s program director for Arctic biology. “It is good to force the debate about climate change … but the downside is that it could be a distraction of a more pressing issue that this very important ecosystem is melting away.”
Until the government’s decision is announced on Jan. 9, 2008, the Fish and Wildlife Service will collect comments and data from the scientific community and general public to assess whether to list the polar bear and what can be done to help the species survive. If listed, the FWS would draft a recovery planning process and require federal agencies to consult the service for any action that could affect polar bears, including greenhouse gas emissions such as coming from coal-powered power plants, electricity generators and automobiles.
Worldwide there are around 20,000 to 25,000 polar bears that live in 19 subpopulations in Alaska, Canada, Russia, Denmark, Greenland and Norway. Alaska is home to approximately 4,700.
A listing under the Endangered Species Act would help protect polar bears from direct impacts, such as industrial activity associated with oil and gas exploration and the release of contaminants. Pollution also can harm the polar bears, though international conventions in recent years have helped reduce this risk.
The polar bear is already on the Marine Mammal Protection Act, which prevents hunting except by native Alaskans. Protective measures — such as re-routing oil and gas pipelines — have already been taken in Alaska to lessen the human impact on the polar bears. A joint U.S.-Russian treaty works to manage the polar bear population shared by the two countries.
The polar bear is listed on the International Union for Conservation of Nature and Natural Resources’ Red List of Threatened Species based on predictions that the global population could decline 30 percent within 45 years as a result of declining habitat quality. Canada and Russia have both acknowledged that the polar bear is a “species of concern.”
By definition, a “threatened” listing under the Endangered Species Act means a species is likely to become endangered in the foreseeable future. An “endangered” listing means a species is likely to go extinct within a significant portion of its range.