Climate change is a familiar term to most, and the associated sea level rise has been one on the trademarks of this environmental threat. While rising seas remain a danger to coastal populations and can damage coastal ecosystems, some ecosystems appear to be building themselves up as the water rises.
A team of researchers that includes Professor of Geology, Environmental Science at University of South Florida’s (USF) St. Petersburg campus, Dr. Joseph Smoak and USF post-doctoral student Joshua L. Breithaupt, recently collaborated on a study that quantifies how rates of carbon burial have changed in southwest Florida coastal wetlands in the past century.
The study, which was published in Journal of Geophysical Research: Biogeosciences, hypothesizes that coastal mangroves and marshes use photosynthesis to change carbon dioxide into plant material like leaves, wood, and roots, and as these materials die over time, they do not decompose the same way they might in a dry soil environment. Instead, daily ocean tides flood the soil, removing the oxygen and allowing dead plant materials to be buried and preserved for hundreds to thousands of years or more.
This "carbon burial" process is a global benefit because it means that carbon dioxide, a greenhouse gas, is stored below ground where it can no longer warm the atmosphere. Mangroves and marshes bury carbon more quickly than most other ecosystems, but little is known about how burial rates change over time.
The team found that carbon burial is 2.5–4.5 times greater today than it was a century ago in mangroves and 1.9–2.3 times greater in marshes. Following the study, the team proposes sea‐level rise as the most likely cause of increased carbon burial.
Rising seas provide the means and opportunity for wetlands to bury more carbon, but if sea level rises too quickly, these wetlands may drown.