[font face=Serif][font size=5]Global warming threat seen in fertile soil of northeastern US forests[/font]
[font size=4]In ‘vicious cycle,’ heat may boost carbon release into atmosphere, UCI-led study finds[/font]

— Irvine, Calif., June 11, 2012 —

[font size=3]Vast stores of carbon in U.S. forest soils could be released by rising global temperatures, according to a study by UC Irvine and other researchers in today’s online Proceedings of the National Academy of Sciences in Washington, D.C.

The scientists found that heating soil in Wisconsin and North Carolina woodlands by 10 and 20 degrees increased the release of carbon dioxide by up to eight times. They showed for the first time that most carbon in topsoil is vulnerable to this warming effect.

“We found that decades-old carbon in surface soils is released to the atmosphere faster when temperatures become warmer,” said lead author Francesca Hopkins, a doctoral researcher in UCI’s Earth system science department. “This suggests that soils could accelerate global warming through a vicious cycle in which man-made warming releases carbon from soils to the atmosphere, which, in turn, would warm the planet more.”

Soil, which takes its rich, brown color from large amounts of carbon in decaying leaves and roots, stores more than twice as much of the element as does the atmosphere, according to United Nations reports. Previously, it wasn’t known whether carbon housed in soil for a decade or longer would be released faster under higher temperatures, because it’s difficult to measure. The team, using carbon isotopes, discovered that older soil carbon is indeed susceptible to warming.

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