Working to keep the West special

Rocky Mountain Forests at Risk

The Union of Concerned Scientists and the Rocky Mountain Climate Organization on September 10, 2014, released a report documenting how climate change is affecting Rocky Mountain forests, and what those effects may be in the future.

The forests of the Rocky Mountains are at greater risk than ever before in U.S. history. An unprecedented combination of tree-killing insects, wildfire, and heat and dryness is already severely affecting key trees of the Rocky Mountains across six states. Scientific evidence shows that climate change is the major force driving these changes.

If today’s trends continue, even hotter and drier conditions could become common. Climate models suggest that important forest tree species may decline substantially in much of the region, replaced by shrublands or grasslands—fundamentally
changing Rocky Mountain landscapes. This report documents the latest evidence on how climate change is already disrupting these forests, and shows what scientists project for the decades ahead. The authors also outline action steps we can take to preserve these iconic landscapes of the American West.

“So far, we have had relatively modest climate changes, but they have already jolted our forests,” said Stephen Saunders, report co-author and president of RMCO. “If we continue changing the climate, we may bring about much more fundamental disruption of these treasured national landscapes.”

The report presents for the first time quantifications from modeled projections by U.S. Forest Service scientists of how future climate change may greatly reduce the area in the Rocky Mountain that is climatically suitable for the region's major types of trees. (See details to the right.) There are substantial uncertainties in such projections, but they suggest the direction and perhaps the magnitude of possible changes. “We don’t want to make too much of the precise numbers, but the point is if we keep changing the climate the way we are, we’re fundamentally changing the nature and composition of the Rocky Mountain forests,” Saunders said.


The full report is here.

Quick Facts

Bark beetle outbreaks have killed trees on a larger scale than ever recorded. In the past 15 years, the beetles have killed trees on western forest lands nearly equal to the size of Colorado.

Wildfires in the West are burning more land. Between 1984 and 2011, there has been a 73 percent increase in the average annual frequency of large wildfires in the Rocky Mountains, leading to an average of 18 more large fires each year.

More western trees are dying for no apparent cause (such as insect infestations or wildfire), with "background mortality" having doubled in recent decades. Scientists suggest that hotter and drier conditions across the West are driving the increase in mortality.

Although all such projections have inherent uncertainty, modeling projections suggest that with continued medium-high emissions of heat-trapping pollution by 2060 the area climatically suitable in the Rocky Mountains for lodgepole pine could decline by about 90 percent, for ponderosa pine by about 80 percent, for Engelmann spruce by about 66 percent, for Douglas fir by about 58 percent, and for aspens by about 61 percent.