Global warming: unwelcome changes at national parks.(up front)(Report)

If you're hoping to see glaciers at Montana's Glacier National Park, don't wait too long, or you might miss them. "Climate change is happening," the National Park Service says in a new brochure for visitors at parks across the U.S. Among the consequences the brochure cites: Stream temperatures and sea levels are rising, coastal erosion is increasing, and changes in weather patterns are leading to drought, heat waves, floods, and fires.

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Those changes have already affected what park visitors can do. For starters, the winter season has been shortened at some parks because of inadequate snow cover for skiing and snowmobiling. Less snow in winter has also created problems for rafters and kayakers in spring and summer.

Climate changes are also affecting what visitors see, according to the brochure. Glacier and Joshua Tree National Parks are losing the very resources for which they're named. At Everglades National Park, rising sea levels could overwhelm mangroves and threaten freshwater wetlands. Yellowstone's grizzlies might be in trouble. In some parks, salmon and trout can't survive in the warming water. Other research, not noted in the pamphlet, warns that desert bighorn sheep in several parks are in danger of extinction, as are Rocky Mountain National Park's white-tailed ptarmigan, a type of grouse.

"The National Parks, because of their location and the unique resources they protect, are places where the effects of these changes are particularly noticeable," said a Dec. 14, 2006, internal park-service memo to Mary Bomar, sworn in as National Park Service director last October. The document describes the service's responses to climate change as "mostly underdeveloped" and requiring "considerable future planning and implementation."

"Climate disruption is the gravest threat the national parks have ever faced," says Stephen Saunders, president of the nonprofit Rocky Mountain Climate Organization and a former deputy assistant secretary of the interior overseeing the park service during the Clinton administration.

What you can do. Before visiting a national park, find its Web site at www.nps.gov/findapark/# and look for information on climate, conditions, and ...