At Risk: America's National Parks

Glaciers, wildlife and forests could disappear entirely from Western national parks because of what a new report by environmental advocacy groups calls the single greatest threat: global warming.

Higher temperatures could make Glacier National Park glacier-free by 2030, and Joshua trees could disappear from Joshua Tree National Park. Mountaintop animals like the furry pika and desert bighorn sheep are on track to become extinct as they run out of terrain while looking for cooler ground.

"This is an across-the-board alarm that some of our most special places are really at risk," said co-author Theo Spencer of the Natural Resources Defense Council Climate Center.

The report was released today by the National Resources Defense Council and the Rocky Mountain Climate Organization. It does not contain new scientific research but summarizes the latest studies into a report that is mostly bad news for America's parks.

"Our Western national parks are really our best example of America's most spectacular natural resources," Spencer said, "but the threat of global warming is going to present many challenges to the parks."

Among the findings: High temperatures and drought could eliminate entire forests in the American Southwest, including those in Mesa Verde National Park. Beaches could become vulnerable to sea-level rise and erosion in places like Golden Gate National Recreation Area and Olympic National Park. And invasive plant species are likely to spread further into Western parks, "causing environmental and economic damage."

Temperatures Climb in the West

Global average temperatures have risen by about one degree Fahrenheit over the last century, which climate scientists agree is a result of heat-trapping greenhouse gases released by burning fossil fuels. But the report notes that in the American West, temperatures have risen twice as fast. Recent studies have linked global warming directly to a pattern of more frequent and more intense wildfires across the West, especially in forests above elevations of 5,000 feet. Scientists cite the forest fires that devastated Yellowstone National Park in the summer of 1988 as a prime example of how global warming can make fires more intense.

Glacier and Grand Teton National parks are also at high risk for increased wildfires. It's a problem that starts with a warmer spring.

"The snow is melting earlier in the year at very regular intervals now, and we're getting much longer fire seasons," said scientist Anthony Westerling of the Scripps Institute of Oceanography. "It dries out much more than before."

Since 1970, warming trends have on average seen snowpack areas melting out as much as three weeks earlier than normal, Westerling said. Water rushes down the gullies and canyons, causing new flooding problems and leaving much of the West high and dry by mid- and late summer. Previously, the areas received enough moisture through August to protect more forests from fire and more species from heat stress.

It's not just at the national parks. Hydrologists estimate that three-quarters of the water supply in the West comes from melting snowpacks, so its increasingly early disappearance will have an increasingly widespread impact on national parks, as well as on most private wilderness areas and Western population centers.

Call to Action

The report calls on the National Park Service and Congress to work to limit global warming pollution and mitigate the damage to parks.

"There is a void of federal action," Spencer said. "We need federal efforts to limit global warming pollution in the near term to slow, stop and reverse global warming pollution from power plants and vehicles. It's as simple as that."

The National Park Service told ABC News today it is reviewing the report, but a representative did not have any immediate comment.

The report lists the 12 national parks most as risk from climate change. The effects range from loss of beaches, wildlife extinction, overcrowding and, in the case of Death Valley, intolerable heat.

The parks include:

Yellowstone National Park in Wyoming, Montana and Idaho

Yosemite National Park in California

Glacier National Park in Montana

Rocky Mountain National Park in Colorado

Bandelier National Monument in New Mexico

Death Valley National Park in California

Glen Canyon National Recreation Area in Utah and Arizona

Golden Gate National Recreation Area in California

Grand Teton National Park in Wyoming

Mesa Verde National Park in Colorado

Mount Rainier National Park in Washington

North Cascades National Park in Washington