Study: Diseased trees may be major cause of global warming

Study: Diseased trees may be major cause of global warming

08 August 2012

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USA– A newly released study finds that diseased trees in forests may be a significant new source of methane that causes climate change, according to researchers at the Yale School of Forestry & Environmental Studies in Geophysical Research Letters.

The study finds that the estimated emission rate from an upland site at the Yale forest is roughly equivalent to burning 40 gallons of gasoline per acre per year. The team noted that diseased trees in northeastern Connecticut contain concentrations of methane that were as high as 80,000 times ambient levels.

“These are flammable concentrations,” said Kristofer Covey, the study’s lead author and a Ph.D. candidate at Yale. “Because the conditions thought to be driving this process are common throughout the world’s forests, we believe we have found a globally significant new source of this potent greenhouse gas.”

The findings could shift attention to combating methane levels released by forests. Researchers say that study is the first to examine the relationship between diseased trees and global warming, and the results are likely to receive additional attention and analysis in the coming months.

“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.”

The trees producing methane are older—between 80 and 100 years old—and diseased, said researchers. While they are mainly outwardly healthy, they are being hollowed out by a common fungal infection that slowly eats through the trunk. The process allows for methane-producing microorganisms called methanogens.

The study comes as a series of recently released studies from NASA suggest that global warming continues to wreak havoc on the U.S. James Hansen of NASA’s Goddard Institute for Space Studies (GISS) in New York and colleagues examined the role of global warming in recent high profile heat waves, such as those in Texas and Oklahoma in the summer of 2011 and in Moscow in 2010.

In a piece published on Monday, Mr. Hansen, who has blamed global warming on carbon emissions, said that previous calculations failed to predict the increasingly prominent role higher temperatures play in feeding extreme weather.

“In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present,” wrote Mr. Hansen.



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