(CNN) -- The setting aside of 187,000 square miles in Alaska as "critical habitat" for polar bears could have an impact on oil and gas drilling, federal and environmental officials said Wednesday.
The U.S. Fish and Wildlife Service (FWS) designated the land along the north coast of Alaska as part of a partial settlement in a lawsuit filed by environmental groups.
"This critical habitat designation enables us to work with federal partners to ensure their actions within its boundaries do not harm polar bear populations," Tom Strickland, assistant secretary of the Interior for Fish, Wildlife and Parks, said in a statement. "Polar bears are completely dependent upon Arctic sea-ice habitat for survival."
The decision does not create a refuge or affect land ownership and private property, but it does give federal authorities leeway when deciding on a project that could negatively affect polar bears.
"It will provide an additional level of consultation," said FWS spokesman Bruce Woods in Anchorage, Alaska. Critical habitat is a specific area where policies can assist a species in recovery.
Environmental groups, including Greenpeace and the Natural Resources Defense Council, welcomed the announcement, but sounded some concerns.
"The critical habitat designation clearly identifies the areas that need to be protected if the polar bear is to survive in a rapidly melting Arctic," Brendan Cummings, senior counsel with the Center for Biological Diversity, said in a statement. "However, unless the Interior Department starts to take seriously its mandate to actually protect the polar bear's critical habitat, we will be writing the species' obituary rather than its recovery plan."
The U.S. government currently considers polar bears as "threatened" rather than the more restrictive "endangered." Officials face a December 23 deadline to explain the designation. The FWS considers the "threatened" label appropriate, given other protective measures, Woods told CNN.
The FWS initially planned to set aside 200,541 square miles, but reduced that to 187,151 due to corrections designed to accurately reflect the U.S. boundary for proposed sea-ice habitat.
The agency said the habitat designation includes areas where offshore drilling occurs. Federal agencies must give approval for much of the drilling.
"If a federal action may affect the polar bear or its critical habitat, the permitting or action agency must enter into consultation with the [Fish and Wildlife] Service," according to an agency statement.
"Polar bears are slipping away," said Andrew Wetzler, director of the Natural Resources Defense Council's land and wildlife program. "But we know that there are crucial protections that can keep them around. Today's designation is a start, especially in warding off ill-considered oil and gas development in America's most important polar bear habitat."
Woods estimates the United States, Russia and Canada have up to 4,500 polar bears between them. Polar bears cover huge territories, so many will be in the critical habitat area at one time or the other.
Another federal agency, the U.S. Geological Survey, has reported a "rapid decline" in Arctic sea ice over the past three decades. It cites global warming as one of the factors.
The Geological Survey's Alaska Science Center is collaborating with the Russia Academy of Sciences and the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, "in developing new satellite remote sensing methods to detect sea ice changes and to elucidate the underlying mechanisms of change."
CNN's Phil Gast contributed to this report.