Bugger. This from New Scientist:
A vast expanse of western Siberia is undergoing an unprecedented thaw that could greatly increase the rate of global warming, climate scientists warn.
Researchers found that an area of permafrost spanning a million square kilometres - the size of France and Germany combined - has started to melt for the first time since it formed 11,000 years ago at the end of the last ice age.
The area, which covers the entire sub-Arctic region of western Siberia, is the world's largest frozen peat bog, and scientists fear that, as it thaws, it will release billions of tonnes of methane, a greenhouse gas 20 times more potent than carbon dioxide, into the atmosphere.
It is a scenario climate scientists have feared since first identifying tipping points - delicate thresholds where a slight rise in the Earth's temperature can cause a big change in the environment that itself triggers a far greater rise in global temperatures.