Climate change drives boom in tree-killing beetle population: study

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Climate change is causing a population boom in a species of tree-killing beetles across a major swath of north America, according to new research published in The Proceedings of the National Academy of Sciences.

The higher-than-usual temperatures and light rainfall over the last decade have allowed the mountain pine beetle to flourish from Mexico to northern Canada, but the National Park Service says it’s especially bad in Rocky Mountain National Park. The beetles burrow deep inside trees and leave cones of sap and sawdust along its side, ultimately killing the trees and creating hazards to park visitors.

While this phenomenon is well known, the beetles mostly focus on the lodgepole pine. However, researchers at the University of Wisconsin-Madison explained Monday that the beetles are now attacking whitebark pine forests in the northern Rocky Mountains as well. This is alarming because those trees grow in a much higher elevation and in areas once thought to be too cold for the beetles to inhabit.

“Warming temperatures have allowed tree-killing beetles to thrive in areas that were historically too cold for them most years,” Professor Ken Raffa said in an advisory. “The tree species at these high elevations never evolved strong defenses.”

The study warns that loss of a significant portion of the whitebark pine forests could lead to decreased flow in nearby streams throughout the warmer, drier months as snow begins to melt sooner due to a lack of shade. That could cause other cascading ecological effects scientists have not yet anticipated.
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