Tens of millions of trees have died in the Rocky Mountains over the past 15 years, victims of a triple assault of tree-killing insects, wildfires, and stress from heat and drought. Global warming is the driving force behind these impacts, bringing hotter and drier conditions that amplify existing stresses, as well as cause their own effects. If climate change is allowed to continue unchecked, these impacts will significantly increase in the years ahead, dramatically reduce the ranges of iconic tree species, and fundamentally alter the Rocky Mountain forests as we know them.
Tree-killing insects have infested and killed more trees, at a faster pace, for longer periods, and over more acreage in western North America than any other known infestation.
Large wildfires have increased throughout the Rocky Mountains in recent decades. Wildfire season is now much longer — more than two months longer — than it used to be.
Extreme heat and drought have stressed trees, and scientists have observed a doubling in tree mortality in recent years, even in areas undisturbed by insects and wildfires.