Smoke billows forth from wildfires blazing in the forests of the Rocky Mountains, in the state of Colorado, USA. These fires have already consumed 125 square miles and are zero percent contained.
What’s propelling these fires are dry conditions made worse by strong winds and an ongoing spruce-beetle infestation. The beetles tunnel under bark, laying eggs that will eventually kill trees. Scientists have reached a consensus that climate change is to blame:
North America is witnessing the largest pine-beetle epidemic in recorded history. From Canada’s Yukon Territory to New Mexico, pine trees by the hundreds of millions are succumbing to a fungus that the beetles carry. The pine needles of infected trees first turn a violent red, then they fall, and, finally, the dead tree topples over. Year by year, communities have watched a scourge advance across mountainsides and through neighborhoods, trees turning from green to red to gray. The beetles now attack 12 pine species, from the high-elevation whitebark pine to the lower-elevation ponderosa and piñon. The blight has devastated 3.3 million acres in Colorado alone since the 1990s.
Beetles kill, die off, and regenerate, all of which is part of a lodgepole pine forest’s natural life cycle. But human activity helped set the stage for the current epidemic. Decades of fire suppression have left the West with dense stands of vulnerable, elderly trees. Climate has also played a role. Frigid winters that usually kill the beetles have become, over the past 20 years, the exception rather than the rule. Earlier snowmelt and longer summers have altered the beetles’ range and life cycle; they now attack pines at higher altitudes and latitudes, and they reproduce twice a year instead of once. Earlier springs and a series of dry years have also weakened trees, turning them into ideal beetle food (click here for more information).