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Coastal marsh migration may further fuel climate change

Coastal swamp migration could further fuel climate change

The mid-Atlantic coast study area includes the Blackwater National Wildlife Refuge in Dorchester County, Maryland. Credit: Chesapeake Bay Program

As rising sea levels push swamps inland across six mid-Atlantic states, the coastal zone will not continue to serve as a carbon sink, but release more carbon into the atmosphere, a new modeling study led by researchers at Duke shows. university.

Previous estimates focused on the potential for a wider area of ​​coastal wetlands to capture and remove more carbon from the atmosphere, where it acts as a greenhouse gas in the form of carbon dioxide. But as coastal swamps invade low-lying forests and freshwater swamps, the loss of trees and decomposition will release more carbon into the air than can be captured by the swamps, further contributing to global climate change.

The study was conducted in conjunction with natural resource agencies in North Carolina, New York, New Jersey, Delaware, Maryland and Virginia. Cards of predicted changes in coastal habitats and carbon due to sea level rise were created to support coastal planning.

“This study and our discussions with states raise many questions about coastal landscape management options in light of these changes, highlighting the importance of reducing greenhouse gases and increasing sea level in general, which is the main driver of all this,” says Katie. Warnell, lead author of the study and policy officer at Duke’s Nicholas Institute for Environmental Policy Solutions. “Carbon is part of the picture. There are many other reasons to maintain wetlands, including coastal protection and fisheries nurseries. We need to consider all of these different factors when making decisions about how to manage our coastal habitats.”

The open-access study was published June 23 in the journal PLOS Climate

The modeling runs looked at land changes in coastal areas up to the year 2104 in scenarios predicting intermediate sea level rise. In 16 of the 19 runs of the model, inland migration has converted the country from a net carbon sink to a net carbon source.

“There may be some things that can be done to protect key areas from conversion,” Warnell said. “In North Carolina, berms and pumps have been used to protect farmland and cities from sea-level rise. While these are expensive, they can be worthwhile in certain areas.”

Another possible option, Warnell said, is preventive logging in vulnerable areas to prevent carbon from being released into the atmosphere after decomposition. As sea levels rise and saltwater replaces freshwater, trees in certain low-lying areas die off, forming ominous “ghost forests.” The tree deaths reduce carbon storage and emit carbon through decomposition.

“In this new study, Warnell and others have made initial estimates of the carbon costs associated with the drowning and salinization of coastal wetland ecosystems,” said Emily Bernhardt, a professor at Duke’s Nicholas School of the Environment, who has extensive haunted forests. studied in the eastern United States. “These early estimates suggest that habitat transitions caused by sea level rise across the Mid-Atlantic Coastal Plain will shift coastal ecosystems from carbon sinks to carbon sources without thoughtful intervention.”

Warnell conducted the new study with Lydia Olander of Duke’s Nicholas Institute for Environmental Policy Solutions and the Nicholas School of the Environment, and Carolyn Currin, who is retired from NOAA’s National Centers for Coastal Ocean Science, part of the National Ocean Service.

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More information:
Katie Warnell et al, Sea level rise causes carbon and habitat loss in the US mid-Atlantic coastal zone, PLOS Climate (2022). DOI: 10.1371/journal.pclm.0000044

Provided by Duke University

Quote: Coastal swamp migration may further fuel climate change (2022, June 23) retrieved June 24, 2022 from https://phys.org/news/2022-06-coastal-marsh-migration-fuel-climate.html

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