How we view national parks -- what we see, what we expect to see -- will surely change as time goes on and the climate continues to alter accepted notions of how national parks appear.

"If you’re talking about forests, or certain kinds of mountain ecosystems, or river ecosystems, I think that the biology has a lot to do with the landscape form," Dr. Philippe Cohen, executive director of the Jasper Ridge Biological Preserve at Stanford, told me in May 2009 while I was researching climate change and the national parks. "And if you see a real significant biological shift, you will also see real significant shifts in how those landscapes are experienced and appear."

Dr. Cohen was convinced that there was nothing to be done about the fallout from human-caused climate change for the next 50 years.

"When all is said and done," he said, "it’s not what happens in the next 50 years, it’s whether there’s going to be anything worth having in 100 years. So, yeah, I think it’s serious stuff. And humans are terrible at long-term thinking, but this is a long-term issue. There’s no doubt in my mind that my son’s life is not going to be as good as mine was. No doubt at all. It’s not something I say to him. It pains me to no end. I take him to places that aren’t going to be around for him to see again. I show him things, (tell him) 'see them now, because when you’re my age they’re not going to be around.'"

Despite this past winter's heavy snowfall in the Northern Rockies, a new report underscores Dr. Cohen's belief, predicting that by mid-century new regime of wildfire in the Rockies will change the face of Yellowstone National Park.

Rising temperatures and more frequent, and larger, wildfires will clear much of Yellowstone's lodgepole forests and replace them with more meadows, shrub vegetation, and open woodlands.

“What surprised us about our results was the speed and scale of the projected changes in fire in Greater Yellowstone,” Professor Anthony Westerling said Monday in a press release from the University of California, Merced. “We expected fire to increase with increased temperatures, but we did not expect it to increase so much or so quickly. We were also surprised by how consistent the changes were across different climate projections.”

The conclusions were based on statistical models based on climate data and wildfire occurrence in the Northern Rockies between 1972 and 1999.

"Our findings indicate that Greater Yellowstone Ecosystem forests are rapidly approaching a threshold beyond which fire occurrence and extent are likely to change the ecosystem qualitatively," a section of their report states. "Recent history shows that a shift in spring and summer temperature of just over 0.5 degrees Celcius above the 1961-1990 average distinguished extreme fire years from most others in the Northern Rockies, and increases in average spring and summer temperatures predicted by 2099 are (about) 4.5-5.5 degrees Celcius for the Global Climate Model scenarios explored here.

"The projected changes in temperatures and fire are not consistent with persistence of the suite of conifer species that have dominated the Yellowstone landscape throghout the Holocene. Rather, the projected climate-fire regime is consistent with lower montane woodland or nonforest vegetation and implies a shift from a climate-limited to a fuel-limited system by mid-century."

One of Professor Westerling's colleagues on the study, which is to be published online this week in the Proceedings of the National Academy of Sciences, Professor Monica Turner from the University of Wisconsin, said the statistical projections indicate that there will be more frequent large fires in the Yellowstone ecosystem.

“Large, severe fires are normal for this ecosystem. It has burned this way about every 100 to 300 years, for thousands of years,” said Professor Turner. “But if the current relationship between climate and large fires holds true, a warming climate will drive more frequent large fires in the Greater Yellowstone Ecosystem in the future."
 

In the researchers’ simulations, years with no large fires — very common in the recent past — become extremely rare by 2050 and are all but eliminated after 2050. The projections show that after 2050, the average annual area burned is about 100,000 hectares, or nearly 400 square miles. By 2075, the average yearly burn exceeds that of the historic season of 1988, when fires claimed more than 1,200 square miles.

    
 
Professor Westerling and his coauthors -- Erica Smithwick, an assistant professor of geography and ecology at the Pennsylvania State University; Mike Ryan, a research ecologist in the U.S. Forest Service, based at the Rocky Mountain Station; Bill Romme, a professor emeritus at Colorado State University; as well as Professor Turner -- said warming alone is likely to lead to a decline in suitable habitat for tree species currently found in greater Yellowstone.

The projected increase in frequency and severity of wildfires could accelerate that process "to a tipping point at which the trees may no longer regenerate," they said.
 
“The climatic conditions projected for the second half of this century are similar to what we see in areas of the west today that have different forest types from Yellowstone’s,” Professor Westerling said. “We don’t know how fast those species will migrate in response to climate change, though, so the immediate response of the ecosystem is hard to predict. Because of its pristine condition, Yellowstone provides an unparalleled natural laboratory to monitor and learn from fire and ecosystem responses to climate change.”