Methane gas is emerging from the seafloor from at least 570 locations along the East Coast that range from near Cape Hatteras, N.C., to the Georges Bank southeast of Nantucket, Mass., according to scientists.
The seepage is widespread, but researchers estimated that the amount of gas was tiny, compared with what is released from all sources each year, the New York Times reported.
In a paper published online Sunday in the journal Nature Geoscience, the scientists, including Adam Skarke, of Mississippi State University, and Carolyn Ruppel, of the United States Geological Survey, reported evidence that the seepage had been going on for at least 1,000 years.
They said the depths of the seeps suggested that in most cases the gas did not reach the atmosphere, but dissolved in the ocean, where it could affect the acidity of the water, at least locally, but methane is a potent, if relatively short-lived, greenhouse gas. The discovery should aid the study of an issue of concern to climate scientists: the potential for the release of huge stores of methane on land and under the seas as warming of the atmosphere and oceans continues.
“It highlights a really key area where we can test some of the more radical hypotheses about climate change,” said John Kessler, a professor at the University of Rochester who was not involved in the research.
Methane seeps occur in many places, but usually in areas that are tectonically active, such as off the West Coast, or that connect to deep petroleum basins, as in the Gulf of Mexico. The Atlantic margin, as the region where the shelf meets the deeper oceanic crust is known, is tectonically quiet and most of the seeps are not thought to be linked to oil and gas deposits.
“This is a large amount of methane seepage in an area we didn’t expect,” Skarke said. “That raises new questions for us.”