University of Alaska, Fairbanks scientists reported the alarming news at the AGU meeting:

A team led by International Arctic Research Center scientist Igor Semiletov has found data to suggest that the carbon pool beneath the Arctic Ocean is leaking.

The results of more than 1,000 measurements of dissolved methane in the surface water from the East Siberian Arctic Shelf this summer as part of the International Siberian Shelf Study show an increased level of methane in the area. Geophysical measurements showed methane bubbles coming out of chimneys on the seafloor.

“The concentrations of the methane were the highest ever measured in the summertime in the Arctic Ocean,” Semiletov said. “We have found methane bubble clouds above the gas-charged sediment and above the chimneys going through the sediment.”

We first heard about this research when Semiletov talked to the U.K.’s Guardian in September. These observations are extremely worrisome for four reasons. First, many fear that a huge methane release is what happened during the Permian-Triassic extinction event and the Paleocene-Eocene Thermal Maximum. Second, releasing even a small fraction of the sub-sea methane would make stabilizing greenhouse gas emissions at non-catastrophic concentrations all but impossible.

Third, as NOAA reported earlier this year, levels of methane rose sharply last year for the first time since 1998:

methane2.jpg

Fourth, the findings are apparently based on very new and credible in situ measurements: “Semiletov said this year’s expeditions used both chemical and geophysical measurement techniques, a first in the area.”

The new data indicates the underwater permafrost is thawing and therefore releasing methane. Permafrost can affect methane release in two ways. Both underwater and on land, it contains frozen organic material such as dead plants and animals. When permafrost thaws, that organic material decomposes, releasing gases like methane and carbon dioxide. In addition, methane, either in gas form or in ice-like methane hydrates, is trapped underneath the permafrost. When the permafrost thaws, the trapped methane can seep out through the thawed soil. Methane, a greenhouse gas 20 times more powerful than carbon dioxide, is thought to be an important factor in global climate change.

The East Siberian Arctic Shelf is a relatively shallow continental shelf that stretches more than 900 miles into the Arctic Ocean from Siberia. The area is a year-round source of methane to the globe’s atmosphere. However, until recently, scientists believed that much of the area’s carbon pool was safely insulated by underwater permafrost, which is, on average, 11 degrees Celcius warmer than surface permafrost.

Since 1994, Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences “has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane “hotspots,” which have now been confirmed using more sensitive instruments.” Why now?

Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia’s rivers due to the melting of the permafrost on the land.

This, of course, would be an amplifying feedback of the very worst kind.

The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.

And, in fact, the NSIDC reported at the AGU that the early autumn Arctic was warming up thanks to the open ocean.

The time to act is January 20, 2009.

This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.