Rocky Mountain Forests at Risk

The forests of the Rocky Mountains are facing a 'triple assault' of tree-killing insects, wildfires, and heat and drought, all amplified by human-caused global warming. Bark beetle outbreaks killed trees on 46 million acres between 2000 and 2012, while large wildfires have increased in frequency and intensity. Iconic species like whitebark pines, quaking aspens, and piñon pines are in catastrophic decline. Projections suggest that if emissions continue unchecked, average regional temperatures could rise by 10°F by the end of the century, potentially replacing conifer forests with shrublands or grasslands. The report advocates for risk assessment, stakeholder engagement, managing for resilience, increasing agency capacity, addressing community vulnerability, and deep reductions in heat-trapping emissions.

• Bark beetle outbreaks in the western United States killed trees on 46 million acres from 2000 to 2012, an area slightly smaller than the state of Colorado. Mountain pine beetles were responsible for half of this acreage.
• Climate change has amplified beetle outbreaks by creating warmer winters that allow more beetles to survive and higher temperatures that enable faster reproduction, allowing some beetles to produce offspring in one year instead of two.
• The frequency and scale of large wildfires in the Rocky Mountain region have risen significantly; one study found a 73 percent increase in the annual number of large wildfires from 1984 to 2011.
• Higher spring temperatures lead to earlier snowmelt and peak streamflows, which leave forests drier and more flammable during the summer, increasing wildfire risk.
• Whitebark pines are in catastrophic decline across western North America due to a combination of blister rust and mountain pine beetle infestations, with mortality reaching 90 to 100 percent in some areas.
• Quaking aspens experienced abrupt and extensive die-offs between 2000 and 2010, particularly in the Southern Rockies, where 1.3 million acres saw significant decline linked to extreme heat and dryness.
• Piñon pines suffered a mass die-off in 2002–2003 triggered by severe drought and exceptional heat, with some sites in Mesa Verde National Park, northern New Mexico, and near Flagstaff, AZ losing approximately 90 percent of their trees.
• The Rocky Mountain region has warmed by 2.1°F since 1895, which is higher than the 1.9°F increase seen across the continental United States.
• If heat-trapping emissions continue unchecked, average temperatures in the six Rocky Mountain states could rise by approximately 6°F by mid-century and 10°F by the end of the century.
• Climate modeling suggests that by 2060, the areas suitable for widespread conifer species—including lodgepole pine, ponderosa pine, Engelmann spruce, and Douglas fir—could decline by 58 to 90 percent.

APA

Funk, J., Saunders, S., Sanford, T., Easley, T., & Markham, A. (2014). Rocky Mountain Forests at Risk. Union of Concerned Scientists. https://www.ucs.org/sites/default/files/attach/2014/09/Rocky-Mountain-Forests-at-Risk-Full-Report.pdf

Chicago

Funk, Jason, Stephen Saunders, Todd Sanford, Tom Easley, and Adam Markham. Rocky Mountain Forests at Risk. Union of Concerned Scientists, 2014. https://www.ucs.org/sites/default/files/attach/2014/09/Rocky-Mountain-Forests-at-Risk-Full-Report.pdf.

Wikipedia

{{cite report |last1=Funk |first1=Jason |last2=Saunders |first2=Stephen |last3=Sanford |first3=Todd |last4=Easley |first4=Tom |last5=Markham |first5=Adam |title=Rocky Mountain Forests at Risk |publisher=Union of Concerned Scientists |date=September 2014 |url=https://www.ucs.org/sites/default/files/attach/2014/09/Rocky-Mountain-Forests-at-Risk-Full-Report.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{funk2014rocky, author = {Funk, Jason and Saunders, Stephen and Sanford, Todd and Easley, Tom and Markham, Adam}, title = {{Rocky Mountain Forests at Risk}}, institution = {Union of Concerned Scientists}, year = {2014}, month = sep, url = {https://www.ucs.org/sites/default/files/attach/2014/09/Rocky-Mountain-Forests-at-Risk-Full-Report.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }