Friday, September 12, 2008

Permafrost find adds to climate calamity

THE blanket of permafrost covering a fifth of the world's land mass traps twice as much greenhouse gas as previously thought — and is therefore much more likely to trigger rapid climate change as it melts, research says.

A paper published in the journal Bioscience estimates that more than 1500 billion tonnes of carbon dioxide and methane is locked in frozen vegetation at high latitudes. This is more than double the amount of greenhouse gas now in the atmosphere.

CSIRO atmospheric scientist Pep Canadell — part of an international team of 19 scientists that worked on the paper — said while it was not possible to accurately predict how much carbon would escape from the permafrost as it warmed, the release of even a fraction would accelerate climate change dramatically.

"With temperatures in the higher latitude estimated to rise by as much as 8 degrees by the end of this century, the world could experience a major melt of large tracts of permafrost in Canada, Russia, Alaska, Norway, Sweden, Finland and Greenland," he said.

The Bioscience paper is a first on two fronts: its researchers accessed long-term Russian data sets that had never been properly analysed, and dug much deeper cores into frozen regions than previous studies.

More than half the world's permafrost — defined as soil that has remained below zero degrees for at least two years — is in the former Soviet Union. It ranges in thickness from 1450 metres in parts of Siberia to less than a metre further south.

Scientists fear the rapid release of carbon from permafrost could produce a feedback cycle, with skyrocketing atmospheric greenhouse levels quickening global warming, in turn causing more melting and release of gases.

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