According to a study published in the Proceedings of the National Academy of Sciences, conducted by researchers at the University of Irvine, California, extensive pockets of Carbon in U.S. forest soils could be released by rising global temperatures.

When scientists heated Wisconsin and North Carolina woodlands only to discover carbon-dioxide emissions increased by up to eighteen times the normal amount, they used carbon-isotopes to concluded 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."

The study reports that forest lands contain about 104 billion carbon reserves and has been one of the biggest unknowns in climate change predictions. Because soil stores more than twice as much carbon as does the atmosphere, suctioned from decaying leaves and roots (form which it get's it brown color), scientists worry that trees and soils could become sources of greenhouse gas emissions rather than repositories.

"Our results suggest that large stores of carbon that built up over the last century as forests recovered will erode with rising temperatures," said Susan Trumbore of the Max Planck Institute for Biogeochemistry and UCI, who led the research team, In collaboration with Margaret Torn, head of the Climate & Carbon Sciences Program at Lawrence Berkeley National Laboratory.

Unfortunatley, this is one factor of climate change that human intervention can not alleviate.

Hopkins asserts to UCI, "We could control how much gasoline we burn, how much coal we burn, but we don't have control over how much carbon the soil will release once this gets going."