Duke University scientists have discovered a previously unknown dual mechanism that slows peat decay and may help reduce carbon dioxide emissions from peatlands during times of drought. "This discovery could hold the key to helping us find a way to significantly reduce the risk that increased drought and global warming will change Earth's peatlands from carbon sinks into carbon sources, as many scientists have feared," said Curtis J. Richardson, director of the Duke University Wetland Center and professor of resource ecology at Duke's Nicholas School of the Environment.

The naturally occurring mechanism was discovered in 5,000-year-old pocosin bogs in coastal North Carolina. Preliminary field experiments suggest it may occur in, or be exportable to, peatlands in other regions as well.

"When we took peat extracts from the southern peatlands and put them into Canadian peatlands, they slowed down decomposition there, too," said Richardson.

Peatlands are wetlands that cover only 3 percent of Earth's land but store one-third of the planet's total soil carbon. Left undisturbed, stored carbon can remain locked in their organic soil for millennia due to natural antimicrobial compounds called phenolics that prevent the waterlogged peat from decaying.

If the peat dries out, however, many scientists have theorized peatlands would switch from storing carbon to pumping it out instead.

"The accepted scientific paradigm is that prolonged drought, coupled with global warming and increased drainage of peatlands for agriculture and forestry, will lower water levels. This could cause peatlands to dry out, decay and release massive amounts of carbon back into the atmosphere," Richardson said. "Our research supports a less dire scenario. It finds that moderate long-term drought might have less impact on the release of carbon dioxide from peatlands than expected."

The reason, he said, lies buried in the peatland soil itself.