WASHINGTON – Methane is leaking into the atmosphere from unstable permafrost in the Arctic Ocean faster than scientists had thought and could worsen global warming, a study said Thursday.

From 2003 to 2008, an international research team led by University of Alaska-Fairbanks scientists Natalia Shakhova and Igor Semiletov surveyed the waters of the East Siberian Arctic Shelf, which covers more than 772,200 square miles (two million square kilometers) of seafloor in the Arctic Ocean.

“This discovery reveals a large but overlooked source of methane gas escaping from permafrost underwater, rather than on land,” the study said.

“More widespread emissions could have dramatic effects on global warming in the future.”

Earlier studies in Siberia had focused on methane escaping from thawing permafrost on land.