March 30, 2009

Climate change: Good and bad for wetlands

U.S. scientists say rising levels of carbon dioxide might result in a rise in seal levels but might also help coastal wetlands survive such an event.

Rising atmospheric carbon dioxide is largely responsible for recent global warming and the rise in sea levels, researchers from the Smithsonian Environmental Research Center in Edgewater, Md., and the U.S. Geological Survey said in a paper. But they said they also determined the increase in CO2 might counterbalance some of its negative effects on wetlands.

Coastal wetlands, the researchers said, must build upward through an accumulation of mineral and organic matter to maintain a constant elevation relative to water levels, otherwise they will drown and disappear. Climate change, however, is causing acceleration in the rise of sea level, which would seemingly put wetlands at risk of excessive flooding.

Our findings show that elevated CO2 stimulates plant productivity, particularly below ground, thereby boosting marsh surface elevation, said Adam Langley, the paper's lead author.

The researchers said their findings are important because the loss of wetlands threatens critical services the ecosystems provide, such as supporting commercially important fisheries, providing wildlife habitat, improving water quality and buffering human populations from oceanic forces.

The study that included Patrick Megonigal appears in the March 23 issue of the Proceedings of the National Academy of Sciences.