Arctic methane leakage cause for concern.

• Position: Greenhouse Effect

A section of the Arctic Ocean seafloor that holds vast stores of frozen methane is showing signs of instability and widespread venting of the powerful greenhouse gas, according to the findings of an international research team led by scientist Natalia Shakhova of the University of Alaska, Fairbanks, and the International Arctic Research Center.

Results show that the permafrost under the East Siberian Arctic Shelf, tong thought to be an impermeable barrier sealing in methane, is perforated and leaking large amounts into the atmosphere. Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming. "The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world's oceans. Subsea permafrost is losing its ability to he an impermeable cap," warns Shakhova.

Methane is a greenhouse gas mere than 30 times more potent than carbon dioxide. It is released from previously frozen soils in two ways. When the organic material--which contains carbon--stored in permafrost thaws, it begins to decompose and, under oxygen-free conditions, gradually release methane. Methane also can be stored in the seabed as gas or hydrates and then released when subsea permafrost thaws. These incidents can be larger and more abrupt than those that result from decomposition. The East Siberian Arctic Shelf encompasses more than 2,000,000 square kilometers of seafloor in the Arctic Ocean. It is mere than three times as large as the nearby Siberian wetlands, which have been considered the primary Northern Hemisphere source of atmospheric methane. Shakhova's research results show that the...