Climate scientists have long warned that global warming could unlock vast stores of the greenhouse gas methane that are frozen into the Arctic permafrost, setting off potentially significant increases in global warming.

Now researchers at the University of Alaska, Fairbanks, and elsewhere say this change is under way in a little-studied area under the sea, the East Siberian Arctic Shelf, west of the Bering Strait.

Natalia Shakhova, a scientist at the university and a leader of the study, said it was too soon to say whether the findings suggest that a dangerous release of methane looms. In a telephone news conference, she said researchers were only beginning to track the movement of this methane into the atmosphere as the undersea permafrost that traps it degrades.

But climate experts familiar with the new research reported in Friday’s issue of the journal Science that even though it does not suggest imminent climate catastrophe, it is important because of methane’s role as a greenhouse gas. Although carbon dioxide is far more abundant and persistent in the atmosphere, ton for ton atmospheric methane traps at least 25 times as much heat.