So far, reactions have been mixed. The state of Alaska and Alaska Native corporations, which rely heavily on oil and gas dollars, say the red tape and the habitat’s vast size will spell huge revenue losses. Environmentalists cheer the move but fear it won’t be enforced. To save polar bears, they say, list them as endangered, not threatened. That would bolster legal protections and leave more room to tackle the chief threat to the animals’ territory: the greenhouse gas emissions causing climate change. —Jeremy Berlin