Last week, the U.S. Fish and Wildlife Service announced its intention to strip federal Endangered Species Act protections from Yellowstone’s grizzly bears. This process is called “delisting” and it means that the feds think the grizzly population around Yellowstone is safe from threats to their survival that date back to 1975. If this proposal is successful, bear management will be turned over to the surrounding states, and they will issue hunting permits.

The decision is required by law to be based on “the best available science.” Nonetheless, tremendous controversy remains concerning the wisdom of delisting Yellowstone’s great bear. Considerable debate rages among independent scientists and conservationists about what constitutes the best science, and how the federal government has interpreted that science. Delisting is not a done deal.

Yellowstone’s grizzlies are currently facing two great threats to their survival: global warming and delisting.

At the time that Lewis and Clark dragged their keelboats up the Missouri River, some 50,000-to-100,000 grizzly bears roamed the West from the Arctic Sea to the Sierra Madre Mountains of Mexico. Today, as few as 1,500 grizzly bears survive south of Canada, most of them in or around Glacier and Yellowstone national parks. The Yellowstone population is isolated, an island ecosystem cut off geographically and genetically from bears along the Canadian border. The feds claim about 700 grizzlies may live in the Yellowstone ecosystem.

Yellowstone’s grizzlies are currently facing two great threats to their survival: global warming, which has already decimated the most important grizzly food in Yellowstone; and delisting, with the attendant plans to open up trophy hunting in Montana, Idaho, and Wyoming.

For centuries, the grizzlies of Yellowstone have fed on nuts from whitebark pine trees. The nut is highly caloric, and the trees grow at a high elevation pine in remote places, serving to separate vulnerable young and mother bears from armed hunters at lower elevations outside the park during hunting season. Mother grizzlies who fed on pine nuts had more cubs and better survival rates. You’d have to go to Siberia to find another such unique relationship.

That symbiosis ended a decade ago. Around 2002, global warming began to heat up the winter temperature around Yellowstone to the point where the larva of the mountain pine beetle could overwinter at higher elevations in the pine trees’ bark. Within five years, 95 percent of the mature, cone-bearing trees were dead. Whitebark pine nuts, the Yellowstone grizzly’s most important food sources were gone and they will not come back in our lifetime.

Nor will it stop there: global warming is the hot wind challenging all species of plants and animals in the Northern Rockies. In Yellowstone, we can expect hot dry weather, a terrifying drought that will bring weeds and diminish the habitat, the carrying capacity for bears. Grizzlies will be forced to forage far afield.

The only certain outcome of delisting the Yellowstone grizzly bears is that it will result in a trophy bear hunt.

The threat of global warming should be enough in itself to preclude delisting. But the federal government is not impressed by climate change. As evidenced by a recent lawsuit over wolverines, Fish and Wildlife administrators dismiss the predictions of climate models as unreliable. The government wants accurate climate predictions out to 2085 before they act. That’s crazy: Nobody has a clue if the bears, or their human constituencies, will even be around in 2085. You can’t dismiss climate change.

The only certain outcome of delisting the Yellowstone grizzly bears is that it will result in a trophy bear hunt. The three states have pushed the feds hard for delisting in anticipation of the revenue such a hunt will bring. But once an isolated group of bears, like Yellowstone’s, begins to die off faster that they are born, they are on the road to extinction.

The growth of the grizzly population has leveled off; the current population estimate is down six percent from 2014. Mortality from all causes, as reported by the government, was 59 dead grizzlies in 2015. Reported mortality is about half of actual dead bears—an accepted rule of thumb. Start adding in the bears that will be shot in the trophy hunt and you could easily approach 200 dead grizzlies in a single year. Even a population of 700 grizzly bears would be doomed to extinction by that much mortality.

Fish and Wildlife pledges to monitor grizzly deaths, but has no funding to do so. With delisting, the federal government will turn over grizzly management decisions outside of the park’s boundaries to three states that everyone knows will show no restraint in killing grizzlies.

The Yellowstone grizzly is marooned, making a last stand against global warming and the guns of autumn. Stripping the great bear of its Endangered Species Act protections will directly contribute to its demise.

Doug Peacock is a former Green Beret medic who has been writing and lecturing about Yellowstone’s bears for more than 40 years. He is the author of five books, including Grizzly Years: In Search of the American Wilderness, and The Essential Grizzly.