The amount of methane being released from permafrost in the Siberian Arctic could rival that being vented from the entire world ocean, suggests new research. The study confirms what scientists have suspected for some time — that substantial quantities of the potent greenhouse gas are being released from sub-sea sites as the Arctic warms.
Between 2003 and 2008, Natalia Shakhova of the University of North Carolina and colleagues measured methane levels at 1,080 locations in the sea above the East Siberian Arctic Shelf, a vast area of shallow sea floor off Russia's northeast coast. From more than 5,000 at-sea observations, they found that more than 80 per cent of the bottom waters, and over 50 per cent of the surface waters, are supersaturated with methane. The researchers detected methane in rising bubble clouds and trapped within the annual sea ice, suggesting that the gas escaped from sub-sea sediments. Combining these measurements, they estimate the annual release of methane from the East Siberian Arctic Shelf at just below 8 million tonnes per year.
The authors note that atmospheric methane levels have risen in recent years, providing further evidence of methane escape.