Tropical wetlands store 80 percent more carbon than temperate wetlands, reports a new study that compared ecosystems in Costa Rica and Ohio.
William Mitsch of Ohio State University and colleagues found that the tropical wetland in Costa Rica accumulated around 1 ton of carbon per acre [2.63 t/ha] per year, while the temperate wetland in Ohio accumulated 0.6 tons of carbon per acre [1.4 t/ha] per year.
“Finding out how much carbon has accumulated over a specific time period gives us an indication of the average rate of carbon sequestration, telling us how valuable each wetland is as a carbon sink,” said Mitsch. “We already know wetlands are outstanding coastal protection systems, and yet wetlands continue to be destroyed around the planet. Showing that wetlands are gigantic carbon sequestration machines might end up being the most convincing reason yet to preserve them.”
Mitsch says that while wetlands are a natural source of methane – a potent greenhouse gas – from decomposition, CO2 sequestration appears to balance net carbon emissions.
“A big issue in wetland science is how carbon sequestration balances against the release of greenhouse gases,” Mitsch said. “Methane is a more effective greenhouse gas than is carbon dioxide in terms of how much radiation it absorbs, but it also oxidizes in the atmosphere. Carbon dioxide does not degrade – it is an end product. If you take that into account, I think wetlands are very effective systems for sequestering carbon.”
Mitsch conducted the study with graduate student Blanca Bernal, who presented the findings Wednesday at the Geological Society of America meeting in Houston.