A report released by conservation groups today named Grand Teton, Yellowstone and Rocky Mountain national parks as the most threatened by climate change associated with global warming.

The report compiled dozens of scientific studies to show that national parks, especially in the western United States, have already started changing as carbon emissions begin to heat the earth.

Released by the Rocky Mountain Climate Organization and the Natural Resources Defense Council, the report said Grand Teton and Yellowstone would likely lose glaciers, fishing, winter recreation, wildlife and vegetation. The parks also might become overcrowded and susceptible to closures because of wildfire.

“Global warming is the single greatest threat to national parks,” said Theo Spencer, a contributing author of the study with the Natural Resources Defense Council. “According to scientists, the first half of 2006 was the warmest on record.”

Spencer went on to say that global warming already has begun to affect snowfall in Western national parks, including Glacier and Grand Teton. The increase in temperatures also is pushing vegetation higher onto peaks and warming rivers.

“Our leaders in Washington need to hit the same trail,” Spencer continued. “We have time, but the window is closing to protect these special places for ourselves and our kids.”

Janet Barwick, who works with the Natural Resources Defense Council protecting grizzly bears, said a threat to the animals’ food supply is imminent. Grizzly bears serve as an indicator species for other wildlife.

“Where there are grizzly bears, the landscape is healthy enough to support a wide range of species including fish, elk and deer,” Barwick said.

Warming temperatures have prompted bark beetles to move to higher elevations where they have started to infest whitebark pine. Seeds of the whitebark pine serve as a primary food source for grizzly bears and drive populations in Yellowstone and Grand Teton.

Whitebark pine is especially susceptible to the insects because they usually inhabit cooler climates and haven’t evolved with the beetles.

“They [whitebark pine trees] have not been able to develop a resistance to these beetles moving higher because of warmer temperatures,” Barwick said. “They [grizzly bears] require these seeds to get them through the wintertime.”

“The whitebark pine might go extinct, this is profoundly disturbing,” said Stephen Saunders with the Rocky Mountain Climate Organization, who explained that Grand Teton and Yellowstone likely will lose mountain meadows and wildflowers, too.

“We are in danger of polluting our parks to death,” he said. “Climate change is going to turn out to be the greatest harm inflicted on our national parks.”

Saunders, a primary author of the study, also served as an undersecretary in the Interior Department under the Clinton administration.

“The National Park Service has clear statutory mandates to protect parks, and these parks are in danger,” he said. “One of the things that they [Park Service personnel] can do is speak out about the dangers.”

“There has never been a risk comparable to this one,” Saunders continued. “This is another wake-up call for all of us. This is a large problem that will affect all of our lives.”

Both Saunders and Spencer said the federal government has lost the initiative on reducing carbon dioxide emissions in time to stop global warming. Instead, the hope lies with states like California, Arizona and New Mexico that have taken steps to limit greenhouse gasses on their own.

National parks such as Grand Teton and Yellowstone have already made the switch to more sustainable practices, like using biodiesel to power cars and trucks.

“We are going to start to do things differently,” said Saunders. “Most of the things we can do are going to save us money and have other benefits, too.”

Spencer explained humanity has about 10 years to start leveling off emissions of global warming pollution, and another 40 or so years to reduce carbon dioxide emissions by half.

“When you put it in the context of national parks,” Spencer said, “that brings it home to people. We need to take action soon and in a meaningful way.”