"Methane is a much more powerful greenhouse gas than carbon dioxide, so a big and rapid release of methane from wetland deposits would represent a huge and rapid positive feedback," said Dave Reay, a climate scientist at Edinburgh University who was not affiliated with the research.
Study author Pancost agreed that methane from wetlands could play a key role in modern warming.
"There is a great deal of methane generated in wetlands by microbial activity. Warming or more precipitation could cause rates of microbially mediated methane production to increase," he said.
Methane already appears to be seeping out of once frozen bogs in Siberia.
"Our measurements have revealed methane-emission hot spots from the bogs in eastern Siberia," said Sergey Kirpotin, from Tomsk State University in Siberia, Russia, who wasn't involved with the study.
"The situation is quite serious and needs urgent investigation," he said.
Siberian permafrost has begun to melt, creating large lakes, Kirpotin explained.
"The frozen peat bogs used to be covered by white lichen, which reflected back sunlight. Now there is more brown surface water, which warms and stimulates the release of methane," he said.
Warmer, wetter weather is likely to promote methane release in wetlands worldwide, and scientists are concerned that this may make it almost impossible to keep a lid on greenhouse gas emissions.
"The wetland methane feedback effect could be equivalent to wiping out all the emissions cuts set out in the [1997 greenhouse gas reduction treaty] Kyoto Protocol," Edinburgh's Reay said.
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