Satellite study finds marsh greenhouse damage

Satellite study finds marsh greenhouse damage

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Rising sea levels caused by global warming may erode the marshlands in the Chesapeake and Delaware bays by the end of the century, according to a study to be published next week.

If sea levels continue to rise at current rates — or the higher rates predicted in some climate models — the two largest marshes on the East Coast could disappear by 2100, the study said.

Marshes act as sinks for carbon, holding it in solid form so it does not escape as carbon dioxide, a greenhouse gas. They also serve as filters, holding sediments and minerals that otherwise would muddy up the bay.

The erosion also has serious repercussions for fisheries because marshlands are spawning grounds and nurseries for saltwater fish.

Michael Kearney, a professor at the University of Maryland, College Park who led the study, used a technique based on 1993 images from a satellite, updated with more recent aerial photography and field surveys. The information is used to determine the overall health of the marsh.

The study will appear in the April 16 issue of Eos, a publication of the American Geophysical Union.

By 1993, about 70 percent of the marshes in the two estuaries already showed damage from the rising waters.

Bill Street, director of watershed restoration at the Chesapeake Bay Foundation, said the latest information is “another example of how the bay ecosystem is out of whack right now.”

Street said the bay is already plagued with pollution and nutrient runoff from farms and industry, leading to a depletion of sea grasses, which are key habitat for blue crabs and young fish.

He said the erosion makes restoring the health of the bay all the more difficult. But while Street and others agree that stopping the rising waters is practically impossible, “what we really need to do is address those issues that we can have some impact on,” he said.

That includes limiting pollution runoff, replanting underwater grasses and growing oyster beds.