Pine beetle infestations warm Canadian forests; fueled by climate change

The mountain pine beetle has ravaged forests across North America, and it has long been thought that infestations can raise surface temperatures by killing trees that once kept temperatures cool. Hard data about this phenomenon didn't exist, but researchers have now collected actual numbers that document how infestations warm Canadian forests, Christa Marshall of Energy & Environment News reports. Though the study focused on British Columbia, its implications could affect forests in the U.S., too, especially in coniferous forests of the Northwest. 

The study, published in Nature Geoscience by scientists at University of Toronto and the University of California, Berkeley, concluded that pine-beetle infestation in British Columbia raised surface temperatures in affected areas an average of 1 degree Celsius. In the worst-hit areas, summer temperatures increased by several degrees. Across all of British Columbia, beetle infestations likely raised temperatures an average of half a degree, even outside forests. "Previous studies have shown that climate change has allowed the beetle to flourish. Our work shows that beetle infestations in turn feed back on climate, creating yet warmer summertime temperatures," said study co-author Holly Maness of Berkeley.

Scientists used satellite and provincial forest data from 1999 to 2010 to reach conclusions. Maness said "the work is distinctive because it translates theory to a specific and very large region," Marshall reports. Scientists found that mild winters driven by climate change fuel infestations, and hot and dry summers make pine trees more susceptible to attack. (Read more)