Water over the Siberian site averages minus 1.8 to 1 degree Celsius, 12 to 17 degrees warmer than the air that helps permafrost on land stay frozen.
Martin Heimann, a scientist at the Max Planck Institute in Germany, said the amount of methane now escaping there is "negligible," though that could change.
"Will this persist into the future under sustained warming trends?" he said in a commentary published in Science. "We do not know."
Warming rivers melt the permafrost
News of methane escaping at the Siberian site follows a similar report last year, when British researchers said they found 250 plumes of methane rising from the seafloor in the Barents Sea north of Norway.
Speaking with reporters yesterday, Shakhova said it appears that river runoff flowing into the area she studied is getting warmer and raising the temperature of water near the ocean floor, where the permafrost lies.
She also noted that water over the East Siberian Arctic Shelf is unusually shallow, with an average depth of just 148 feet. That means the methane that escapes from the ocean floor has little chance of dissolving or oxidizing as it rises to the sea surface.
"It just escapes," she said.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500