US national parks face 'greatest threat', Senate told

Shanta Barley, New Scientist 26 Aug 09;

US national parks could be changed so significantly by global warming that they will be lost forever, senators were warned this week.

"If we continue adding heat-trapping gases to the atmosphere in the way we now are, we could, for the first time, lose entire national parks," Stephen Saunders, president of the Rocky Mountain Climate Organization told the Senate Committee on Energy and Natural Resources, National Parks Subcommittee.

At a subcommittee hearing in Colorado on Monday chaired by John McCain (Rep) and Mark Udull (Dem), senators were presented with a picture of how state parks are likely to be influenced by climate change. Joshua trees, Mexican spotted owls, wildflowers, glaciers and aspen will suffer as snowfall declines and temperature, sea levels, wildfires and pest outbreaks rise, ecologists warned the committee.
Double whammy

Low-lying reserves such as Ellis Island National Monument and Tortugas National Park, which sits less than 90cm above sea level in the Gulf of Mexico, "could be lost to rising seas," Saunders said.

Joshua Tree National Park could lose all its Joshua trees, he warned. The emblematic aspens of the West are already suffering: the area in Colorado affected by "aspen dieback" increased four-fold between 2006 and 2008.

Climate change is causing a "double whammy" of wildfires and pest outbreaks, said Herbert Frost, Associate Director for Natural Resource Stewardship and Science at the National Park Service. Wildfires now take over a month to die out, whereas they used to last no more than ten days, Frost told the committee.
Pest outbreak

Tree-killing pests are also thriving as the harsh winters which used to keep their numbers in check lose their edge: bark beetles have already decimated as much as 90 per cent of Colorado's lodgepole forests, Alice Madden, the Climate Change Coordinator at the Office of the Governor in Denver, Colorado, told the committee.

Climate change will also impact our tundra, warned Saunders. A 5 to 6˚C rise in temperature will wipe out tundra in Rocky Mountain National Park altogether, he said, replacing it with bush and forest.

Mountain meadows, which depend on heavy snow fall and a short growing season to keep tree seedlings from surviving, will also dwindle as temperatures rise, said Saunders. "Scientists have already detected a loss of mountain meadows in Glacier, Olympic, Sequoia/Kings Canyon, and Yosemite national parks," he told the committee.

What's more, the wildflowers which normally carpet alpine meadows are also under threat: experimental warming has demonstrated that a 4˚C rise in temperature causes wildflowers to be replaced with sagebrush, said Saunders.