This was a tough summer for forested states in the United States. Thanks to severe drought, disease and pine beetle infestations spurred on by warming temperatures, thousands of acres of forest land succumbed to wildfires in almost a dozen states. Colorado undoubtedly fared the worst, racking up at least $449.7 million in damages.

Many pointed to the wildfires as evidence that climate change is already having a devastating effect on our environment. Now new research shows that the dry, infested forests may be creating the very conditions that led to their destruction. Researchers at the Yale School of Forestry & Environmental Studies say some diseased trees release methane at a level that may be a globally significant source of the potent heat-trapping gas, according to the study published in Geophysical Research Letters.

After sampling 60 trees in northeastern Connecticut, Yale researchers found concentrations of methane as high as 80,000 times ambient levels. According to Kristofer Covey, the study‚Äôs lead author and a Ph.D. candidate at Yale, this is enough methane to be flammable, which may explain why damaged forests burn out of control so quickly.

Researchers found that red maple, a common North American tree, had the highest methane concentrations, but other common species, including oak, birch and pine were also producers of the gas. The rate of methane emissions was 3.1 times higher in the summer, suggesting that higher temperatures may lead to increasing levels of forest methane that, in turn, lead to ever-higher temperatures. All of the trees sampled were between 80 and 100 years old and infected by a trunk-rotting fungus that creates the perfect environment for methane-producing microorganisms.

“If we extrapolate these findings to forests globally, the methane produced in trees represents 10 percent of global emissions,” said Xuhui Lee, a co-author of the study, and Sara Shallenberger Brown, professor of meteorology at Yale. “We didn’t know this pathway existed.”

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