Pine Beetle Attacks are Warming Canada
It is known that mountain pine beetle infestations have the potential to raise nearby air temperatures by killing off trees that provide a natural refrigerator effect for forests. Now, researchers are releasing hard numbers documenting how the pests' invasions affected a specific place.In a study published in Nature Geoscience, scientists at the University of Toronto and the University of California, Berkeley, reported that the beetle scourge in British Columbia raised surface temperatures in affected areas by 1 degree Celsius on average in the summer. In the worst-hit areas where provincial forests were wiped out, the summer temperature increase was several degrees higher.Large red patches in the tree cover of Manning Park in British Columbia show the trees killed by the mountain pine beetle. Photo courtesy of Flickr."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 Holly Maness, a study co-author and a postdoctoral fellow in the department of earth and planetary science at UC Berkeley. When the numbers are scaled provincewide, the beetle infestations likely raised temperatures on average by half a degree Celsius, even outside forested areas, she said. The scientists examined the period between 1999 and 2010, using satellite and provincial forest data. The work is distinctive because it translates theory to a specific and very large region, according to Maness. It also raises questions about how beetle infestations may affect precipitation patterns in Canada, she said. The team found that bark beetle infestations increased outgoing heat in the forests -- via air flows -- by roughly 8 percent. This could interact with cloud formations, Maness said, although the exact way the 8 percent increase could influence weather, air circulation and precipitation is not fully understood. Outgoing forest heat via radiation "fluxes" increased by 1 percent in beetle-infested areas, the study said.