Arctic is releasing carbon

A vast outcrop of the Arctic Siberian coast that had been frozen for tens of thousands of years is releasing huge carbon deposits as rising temperatures thaw parts of its coastline, a study warned.

The carbon, a potential source of earth-warming CO2, has lain frozen along the 7,000-kilometre northeast Siberian coastline since the last Ice Age.

But atmospheric warming and coastal erosion are gnawing at the icy seal, releasing about 40 million tonnes of carbon a year – 10 times more than previously thought, said a study in the journal Nature.

Two-thirds of the carbon escapes into the atmosphere as carbon dioxide (CO2) and the rest becomes trapped in higher layers of ocean sediment.

About half the carbon pool in soil globally is held in permafrost in the Arctic, a region that is experiencing twice the global average of climate warming, said the study led by researchers at Stockholm University.

Earlier this week, US scientists said the sea ice in the Arctic Ocean had melted to its smallest point ever.