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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.”

As a result of this research, it is clear that salt marshes are more than just beautiful ecosystems. They are an essential component of our planet’s biodiversity and play a vital role in our coastal ecosystems and economies. 

If we do not act quickly to address climate change and its impacts on our environment, we could lose these ecosystems, with disastrous consequences for both our planet and ourselves.

More about salt marshes

Salt marshes are vital coastal ecosystems that have a significant impact on both humanity and the environment. They are characterized by their unique vegetation, which thrives in the saline conditions of coastal estuaries, lagoons, and bays.

One of the most important roles of salt marshes is their ability to act as carbon sinks, sequestering large amounts of carbon from the atmosphere and storing it in the soil. They are also crucial for nitrogen cycling, converting nitrogen from agricultural runoff and other sources into forms that can be used by other plants and animals.

Salt marshes also provide important habitat and nursery grounds for a wide variety of species, including fish, shellfish, and coastal birds. They serve as a natural buffer, protecting coastal areas from storm surges and wave action, and are an important component of coastal tourism and recreation industries.

Under severe threat

However, these important ecosystems are under threat from human activities, including coastal development, pollution, and climate change. 

Rising sea levels and increased storm activity due to climate change are causing salt marshes to become submerged and erode, with potentially devastating consequences for coastal communities and ecosystems.

The loss of salt marshes could have far-reaching impacts on the planet’s biodiversity, food security, and human livelihoods.

Many fish and shellfish species rely on salt marshes as breeding and feeding grounds, and the loss of these ecosystems could lead to declines in important commercial and recreational fisheries. 

Additionally, the loss of carbon sequestration and nitrogen cycling could have far-reaching impacts on global climate change and food production.

Protecting and preserving salt marshes is essential for the health of our planet and our communities. This includes taking steps to reduce greenhouse gas emissions, mitigate the impacts of climate change, and limit human activities that degrade salt marsh ecosystems. 

By taking action now, we can ensure that these vital ecosystems continue to provide benefits to both humanity and the environment for generations to come.


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