But the evidence that Mitton and his colleagues are piecing together has yet to persuade many people in the U.S. Forest Service and the National Park Service, let alone the average Coloradoan, that climate change has driven the pine-beetle epidemic.
“There’s a lot of discussion” about whether climate change influenced the epidemic, said Cal Wettstein, the Forest Service’s incident commander who coordinates the regional response to the epidemic. “Of course, I’m not an expert on it. It’s possible that it might be a factor. It’s not the driving factor.”
Mack says, “There’s no question that we’re seeing changes in different aspects” of ecological life at Rocky Mountain National Park. But he warned that the shifts aren’t “the dramatic effects that people tend to associate with climate change.”
Mack and Wettstein remain focused on dealing with an immediate consequence of the outbreak: keeping people and infrastructure safe from falling trees. Wettstein estimates that 100,000 dead trees will fall every day for the next 10 years in northern Colorado and southern Wyoming. A falling tree could kill a hiker, take out a power line, or block a back road.
It’s tough to connect an ecological phenomenon to a single factor. It’s also tough to predict the local manifestation of global warming in a mountainous state that sees a lot of weather variation. “I think that what’s uncertain are the details,” said professor William Bowman, director of the lab that Mitton and others use for studies of ecology and climate change. “What I see is not so much disagreement over whether climate change will occur; it’s how it will be manifest.”
Coloradoans have noticed that species are shifting their ranges, snows are melting earlier, and—particularly this year—warm weather is coming mighty early. Set aside the polarized climate-change debate, and you’ll find communities dealing with a set of conditions that aren’t obviously linked to rising global temperature and that don’t, on a day-to-day basis, constitute a catastrophe. They’re not yet seeing evidence that could spur action on carbon emissions. But if the climate models are correct, the changes that Coloradoans are already experiencing herald a very challenging future for the West.
THE FIRE THIS TIME
The best way to view the effects of climate change in Colorado, it turns out, is from a car. Take Interstate 70 west from Denver toward Glenwood Springs, and you’ll move from the Great Plains to high-altitude pine forest in an hour. As mountains unfurl and you drive into areas dense with lodgepole pines, the full visual impact of the epidemic asserts itself. New growth and untouched species amidst the devastation don’t make the skeleton pines any less spooky.
The steep descent into Dillon presents perhaps the most dramatic sight on the highway. Cars shoot through the Eisenhower Tunnel, bored straight through solid mountainside, and pop out into a valley where in some places 70 percent of the trees are dead. Residents of Summit County have been grappling with a changing forest for almost a decade, and that has meant wrestling with fear, confusion, misinformation, apathy, and a sense of helplessness. In some ways, their experience is a microcosm of the larger climate-change debate.
A bum knee doesn’t stop Howard Hallman, an earnest man kitted out in the Colorado uniform of fleece vest and sturdy boots, from clambering over the land that separates I-70 from Straight Creek. On one side of the stream, the mountainside is designated wilderness; on the other, it’s designated roadless, making it almost impossible to drive tree-removal equipment in. A wildfire on either side could send dirt and debris tumbling into Dillon’s only water source, but there’s little residents can do—legally or logistically—to protect the creek.
“We have human habitat, we have housing, we have recreation, so we can’t really let things run their course,” Hallman said. Like a lot of Coloradoans, he worries that the dead trees heighten fire risk. Scientists dispute the extent to which beetle-kill trees affect fire behavior, but laypeople and experts alike are certain of one thing: In a dry year, the forest will burn. And this year looks to be extremely dry.
Hallman’s community group, the Forest Health Task Force, worked with the Forest Service to clear-cut a 60-acre patch near Straight Creek, hoping to mitigate the fire hazard. The patch of bare ground looks pathetically small measured against the surrounding mountains.
“Does climate change play a role in it? For sure, I think.... Scientists are still really studying it.” —Dan Gibbs
From the brewpub where the task force meets each month, patrons can look out the window and see the Dillon Reservoir. The fact that the towns of Dillon, Frisco, and Silverthorne lie clustered around a reservoir that none of them can draw water from is a testament to the quirks of Western water appropriation. Constructed in the 1960s by Denver Water, the public utility for the state’s capital, the Dillon Reservoir is Denver’s property. Runoff from snows that blanket Summit County flows into the reservoir and then courses through the mountains for 70 miles to the sprawling metropolitan area on the plains. Summit County snowmelt that doesn’t get siphoned off to local towns, Denver, or Colorado Springs eventually joins the Colorado River, the primary water source for close to 40 million people across the western United States.