Amid heated debate on climte change, global warming that may push sea levels to rise affecting the coastal areas and small island nations across globe, here is a news that should soothen the environmental critics. The coastal marshes are more resilient than previously believed to the sea-level rising, says a new Duke University study.
The research shows that there is significant boost in marsh plant productivity whenever the elevated levels of atmospheric carbon dioxide are witnessed and the marshes trap more sediment and create more organic soil, which results in increased rates of accretion and corresponding increase in thresholds for marsh drowning by up to 60 percent.
Coastal marshes absorb and store large amounts of carbon dioxide from Earth’s atmosphere; they help filter out pollution in coastal waters; provide habitat for wildlife; help protect coastlines from erosion and storm surge; and can store huge amounts of floodwater, reducing the threat of flooding in low-lying coastal areas.
"Essentially, we found it’s a self-rising mechanism marshes use to build themselves up," said Marco Marani, professor of ecohydrology at Duke’s Nicholas School of the Environment and Pratt School of Engineering. "As levels of atmospheric carbon dioxide increase, more CO2 gets taken in by marsh plants. This spurs higher rates of photosynthesis and biomass production, so the plants produce more sediment-trapping growth above ground and generate more organic soil below ground."
The so-called "CO2 fertilization effect" may also contribute to a stabilizing feedback in the climate system as increased biomass production and organic deposition in marshes sequester larger amounts of carbon dioxide, says the study.
However, this will not stop another serious threat faced by marshes from sea-level rise, sediment starvation, which will remain, cautions Katherine M. Ratliff, a doctoral student at Duke’s Nicholas School, who was lead author of the study.
The study has been published in the Proceedings of the National Academy of Sciences.
An aerial image with false colors shows marsh elevations in the Venice lagoon. (Photo: Marco Marani, Duke University)