BILLINGS, Mont. — U.S. wildlife officials are withdrawing proposed protections for the snow-loving wolverine in a course reversal announced Tuesday that highlights lingering uncertainties over what a warming climate means for some temperature-sensitive species.
Wolverines, or "mountain devils," are rarely seen members of the weasel family that need deep, late-season snow to den.
But while there is broad consensus climate change will make the world warmer, drilling down to determine what that means for individual species remains difficult. That's stoking sharp disagreement over the fate of wolverines, with one researcher calling Tuesday's withdrawal a travesty of science.
U.S. Fish and Wildlife Service Director Dan Ashe said in an interview with The Associated Press that predictions about climate change's localized impacts remain ambiguous.
Rejecting the conclusions of most outside experts and some of the agency's own scientists, Ashe said the uncertainty made it impossible to determine whether less snow cover would put wolverines in danger of extinction in coming decades.
The decision carries potential ramifications for other species affected by climate change — including Alaska's bearded seals, the Pacific walrus and dozens of species of corals — as scientists and regulators grapple with limits on computer climate models.
"Climate change is a reality," Ashe said. "What we don't know with reliability is what does climate change mean for denning habitat that wolverines prefer."
He added that evidence of an expanding population means "it's possible wolverines are adapting and continuing to adapt."
A leading wolverine expert whose work has been cited extensively by the Fish and Wildlife Service said any suggestion that wolverines can adapt to the absence of snow was "preposterous."
"What's happened today is nothing less than a travesty of science," said Jeff Copeland, a research biologist and executive director of The Wolverine Foundation in Idaho. "This was not a scientific process. It was a political process."
Federal wildlife officials last year said future temperature increases could melt the snowfields occupied by wolverines in some high elevation mountain ranges in the Lower 48 states. They called for increased protections to keep the species from going extinct.
The first indication the government's stance had changed came last month, in a leaked memo from a Fish and Wildlife regional director in Denver, who overturned her staff's recommendations for wolverine protections.
Wildlife advocates blamed the reversal on pressure from state wildlife agencies. Attorneys representing more than a dozen groups on Tuesday pledged to sue Ashe's agency to force it to adopt protections.
Officials from western states including Montana, Wyoming, Utah and Idaho had opposed federal protections, saying the animal's population has increased in some areas in recent decades.
That's similar to what happened to the bearded seal. It received protections from the National Marine Fisheries Service in 2012 only to lose them last month, when a federal judge sided with Alaska officials and said 100-year projections of sea ice losses were based on "speculative" climate model forecasts.
At least two other species, the American pika and black-footed albatross, were denied protections after the government concluded some of the animals might die off because of climate change, but enough would survive to keep the populations viable.
Yet Ashe said when the evidence is clear, his agency will act. He cited a 2008 decision to list the polar bear as a threatened species because of Arctic sea ice losses from global warming.
For wolverines, the withdrawal also means an end to the federal government's proposal to reintroduce the species to the southern Rocky Mountains of Colorado, Wyoming and New Mexico. Ashe said he will encourage the states to pursue reintroductions on their own.
Once found throughout the Rocky Mountains and in California's Sierra Nevada mountain range, wolverines were wiped out across most of the U.S. by the 1930s due to unregulated trapping and poisoning campaigns, said Bob Inman, a wolverine researcher with the Wildlife Conservation Society.
In the decades since, they largely have recovered in parts of the West, where 250 to 300 of the animals live, but not in other parts of their historical range.
Steve Running, a University of Montana ecology professor and member of the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change, said computer models used to predict future temperatures and precipitation amounts become less accurate as they go further out in time. That makes it hard to localize potential impacts.
But Running added climate trajectories over recent decades give an accurate depiction of what's in store and should be used by wildlife managers to make long-term decisions. Over the past 50 years, he said, snow melt in the Northern Rockies has shifted two weeks earlier in the spring.
"If you take 50 more years and think of it as two more weeks earlier, wolverines are probably one of the classic poster children of a highly temperature-sensitive animal," he said.