Study Finds Wetlands Can Speed Effect of Carbon Dioxide on Global Warming

Marshes, rice paddies and other wetlands may amplify the global-warming effect of future increases of carbon dioxide in the atmosphere, a study suggests.

Scientists found that when salt marsh sites were subjected to twice the normal concentrations of carbon dioxide, they gave off elevated levels of methane. Methane has more warming potential than an equivalent amount of carbon dioxide.

The increase in carbon dioxide stimulates more photosynthesis and buildup of carbon in the plants, and when the plants die and decompose, more methane is released into the air, researchers said.

The work shows that carbon dioxide has an indirect impact on global warming as well as a direct one, researchers write in the July 7 issue of the journal Nature.

The work was done by researchers at the Woods Hole Oceanographic Institution in Woods Hole, Mass., the Smithsonian Environmental Research Center in Edgewater, Md., and Michigan State University’s Kellogg Biological Station in Hickory Corners, Mich.