Scientists predicted wetland soil accretion (or growth) rates in relation to predicted sea level riseusing a model and data from numerous tidal salt and freshwater wetlands around the United States. The model results, published in Earth's Future , suggestedthat, on average, softer organic components of East Coast marsh sediments do not accretefast enough in volume and height to keep marshes from drowning in the face of predicted sea level rise without additional mineral sediment inputs.

Tidal salt marshes like this one in South Carolina may not be able to keep pace with long-term rising sea levels according to a new NCCOS study. Credit:University of South Carolina

Led by the University of South Carolina, the multi-institutional team used a statistical mixing model and data from 5,075 wetland soil samples taken from 33 varied wetland sites in estuaries from 14 states to predict wetland soil accretion rates.The model suggests the maximum steady state organic soil accretion is less than or equal to 0.3 cm per year, while current rates of sea level rise range from 0.18-0.60 cm per year. This indicates primary production will likely fail to keep marshes above predicted accelerated sea level rise and result in long-term elevation loss and eventual drowningwithout mitigation or marsh restoration efforts.

The research is from the NCCOS-sponsored Ecological Effects of Sea level Rise in the Northern Gulf of Mexico project, involving scientists from 11 institutions.

For more information, contact David.Kidwell@noaa.gov.