Rising atmospheric carbon dioxide is largely responsible for recent global warming and the rise in sea levels. However, a team of scientists, including two Smithsonian ecologists, have found that this same increase in CO2 may ironically counterbalance some of its negative effects on one of the planet's most valuable ecosystemswetlands. The team's findings are being published in the Proceedings of the National Academy of Sciences the week of March 23.
The team conducted their study for two years (2006 2007), during which they focused on the role that organic matter, both growing and decaying, plays on soil elevation in wetlands and the effect CO2 has on this process. Coastal wetlands must build upward through the 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. Patrick Megonigal, the paper's corresponding author, added "We found that by stimulating root growth, thus raising a marsh's soil elevation, elevated CO2 may also increase the capacity for coastal wetlands to tolerate relative rises in sea level." Both scientists are ecologists at the Smithsonian Environmental Research Center in Edgewater, Md.
These findings bear particular importance given the threat of accelerating sea-level rise to coastal wetlands worldwide. Some evidence suggests that only a two-millimeter increase in the rate of sea-level rise will threaten and possibly eliminate large portions of mid-Atlantic marshes. And the loss of these wetlands threatens critical services that the ecosystems provide, such as support
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