Permafrost melting a growing climate threat

SINGAPORE (Reuters) - The amount of carbon locked away in frozen soils in the far Northern Hemisphere is double previous estimates and rapid melting could accelerate global warming, a study released on Wednesday says.

Large areas of northern Russia, Canada, Nordic countries and the U.S. state of Alaska have deep layers of frozen soil near the surface called permafrost.

Global warming has already triggered rapid melting of the permafrost in some areas, releasing powerful greenhouse gases carbon dioxide and methane.

As the world gets warmer, more of these gases are predicted to be released and could trigger a tipping point in which huge amounts of the gases flood the atmosphere, rapidly driving up temperatures, scientists say.

"Massive amounts of carbon stored in frozen soils at high latitudes are increasingly vulnerable to exposure to the atmosphere," said Pep Canadell, executive director of the Global Carbon Project at Australia's state-funded Commonwealth Scientific and Industrial Research Organization.

"The research shows that the amount of carbon stored in soils surrounding the North Pole has been hugely underestimated."

The study is published in the latest issue of Global Biogeochemical Cycle.

Canadell said a four-year study of the latest research on permafrost, data from new drilling projects as well as the release of previously unpublished data from the Russian Academy of Sciences had led to a rethink of carbon levels.

"Projections show that almost all near-surface permafrost will disappear by the end of this century exposing large carbon stores to decomposition and release of greenhouse gases," he said in a statement.