Ten national parks in California could be headed for steep temperature increases over the next century that could alter their ecosystems and drive tourism from some of the more iconic settings in the western United States. This is the conclusion from a new report from the Natural Resources Defense Council and the Rocky Mountain Climate Organization.

The study applied "medium to high" future emissions estimates of heat-trapping gases, as assumed by the California state government, to models designed to assess what effect climate change would have on national parks like Yosemite, Death Valley, Redwood, Joshua Tree and Sequoia.

The predictions are stark.

Yosemite, for instance, would see its average temperature rise by 7.5 degrees by 2070 to 2099 if emissions remain within a medium-to-high range of estimates modeled by the Intergovernmental Panel on Climate Change (IPCC) in 2007. Death Valley, already the hottest spot in the United States, would see a temperature increase of 8.1 degrees under the same scenario.

The spike would also mean that Joshua trees -- which give Joshua Tree National Park its name -- would likely disappear because the trees need freezing temperatures to set seeds. This could eliminate the trees from Death Valley National Park and Mojave National Preserve, as well.

And the increase could mean trouble for redwoods up north, where coastal fog is key to the survival of some of the world's tallest trees. The report says climate change has already diminished fog by 30 percent along the coast, endangering redwoods in Redwood National Park and Muir Woods National Monument. Steady emissions levels could diminish fog levels even further, the report says.

Low-lying areas are submerged

Stephen Saunders, the study's lead author and president of the RMCO, said the changes could mean trouble for tourism in particular. He said national parks in California draw 34 million visitors a year, produce 19,000 jobs and spending of $1.24 billion, all of which could be in jeopardy if the parks themselves lose their appeal and become less hospitable to tourists.

Saunders also defended the study's use of medium-to-high emissions estimates from the IPCC, saying he expects the international body to issue even higher greenhouse gas predictions in its next five-year study, in 2012.

"These estimates could actually be worse," he said in an interview. "I sure hope they're nowhere near that."

The report also pegged likely sea level rise at anywhere from 2 to 4.7 feet, which could inundate low-lying recreation areas like the Point Reyes National Seashore, Golden Gate National Recreation Area and Redwood National Park.

Saunders, a deputy assistant of Interior during the Clinton administration, said the sea level estimates are well within the realm of possibility, again referencing IPCC data and the state-funded California Climate Change Center.

"The sea level rises are taken exactly from California state government," he said. "The range is the range."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500