Common sense and science tells us that trees are one of the few things that has helped bear the brunt of increased carbon dioxide levels, but could trees also be a major source of global warming? New research from the Yale School of Forestry & Environmental Studies show that trees exposed to fungal rot have an abnormally high amount of methane that could be contributing to climate change and rising temperatures.
"If we extrapolate these findings to forests globally, the methane produced in trees represents 10 percent of global emissions," said co-author of the study Xuhui Lee. "We didn't know this pathway existed."
Normal methane concentrations in the air run around 2 parts per million (ppm). Concentrations of methane in the diseased trees are as high as 15,000 ppm.
"These are flammable concentrations," said lead author, Kristofer Covey, who is working on his Ph.D. at Yale.
Methane is a highly potent greenhouse gas that is "20 times more effective in trapping heat in the atmosphere than carbon dioxideover a 100-year period," according to the EPA.
The reason for the high levels of methane is due to a fungal rot that slowly hollows out the insides of the trees, usually aged between 80 and 100 years, and creates a favorable environment for methane-producing organisms to grow.
The impact of these diseased, methane-producing trees is significant enough to cause the researchers some concern.
"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," said Covey.
To arrive at the results, the researchers looked at more than 60 trees in the Yale-Myers Forest in northeastern Connecticut. The species of trees with the highest level of methane was the red maple, followed by the oak, birch, and pine.
Levels of methane also seemed to be 3.1 times higher in the summer, suggesting that rising temperatures feed the methane-producing process, which in turn creates higher temperatures in a vicious cycle.
"These findings suggest decay in living trees is important to biogeochemists and atmospheric scientists seeking to understand global greenhouse gas budgets and associated climate change," said Covey.