Marshes. Flickr

World - 90 percent of Earth's salt marshes will be underwater by the year 2100

Salt marshes have been a key component of coastal ecosystems for centuries, acting as carbon sinks, playing a significant role in nitrogen cycling, and providing critical habitats and nurseries for many fish, shellfish, and coastal birds.

These low-lying wetlands are some of the most biologically productive ecosystems on the planet, and their loss could have a profound impact on coastal communities and economies.

New research from the Marine Biological Laboratory at the University of Chicago warns that over 90 percent of the world’s salt marshes could be underwater by the end of the century, with Great Sippewissett Marsh in Falmouth, Massachusetts, serving as an example of what is to come.

The study, published in the journal Science of the Total Environment, is based on a 50-year investigation of the salt marsh and has been supported by the U.S. National Science Foundation.

Francisco (Paco) Moore, a program director in the NSF’s Division of Environmental Biology, commented on the research:

“Salt marshes shape our coastlines and create an ecological foundation for coastal economies both directly and indirectly. The direct impacts of saltmarsh loss would be staggering; the indirect effects may be larger still. These marshes are fundamental to coastal commercial and recreational fisheries and are a living buffer stabilizing our coastlines.”

How the study was done

The researchers have been mapping vegetative cover in experimental plots in the Great Sippewissett Marsh since 1971, examining whether increased nitrogen in the environment would affect the species of marsh grass. Due to the length of the study, they were also able to detect the effects of climate change on the ecosystem, particularly those resulting from accelerating sea-level rise.

According to the study’s lead author, Ivan Valiela, “Even under conservative sea-level estimates, more than 90% of the salt marshes of the world will likely be submerged and disappear or be diminished by the end of the century.”

What the researchers learned

The researchers discovered that increased nitrogen favored higher levels of vegetation and marsh surface accretion but that no matter how much nitrogen they applied to the marsh, these ecosystems would not be able to outpace submergence from global sea-level rise.

Valiela warns, “This is not a prediction from isolated scientists worried about little details. Major changes are going to be taking place on the surface of the Earth that will change the nature of coastal environments.”

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