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But it is unclear if the emissions are new or have been going on unnoticed for centuries - since before the Industrial Revolution of the 18th century.
The study, which appears today in the journal Science, says about 8 million tonnes of methane a year, equivalent to the annual total previously estimated from all of the world's oceans, were seeping from vast stores long trapped under permafrost below the seabed north of Russia.
"Subsea permafrost is losing its ability to be an impermeable cap," says study co-author Dr Natalia Shakhova, a scientist at the University of Fairbanks, Alaska.
The experts measured levels of methane, a gas that can be released by rotting vegetation, in water and air at 5000 sites on the East Siberian Arctic Shelf from 2003 to 2008. In some places, methane was bubbling up from the seabed.
Comment: The Climate Change scam is steadily unravelling, at long last. You can see the progress being made when a business publication such as Business Investors Daily has seen through the scam, is alerting its business readers to the scam and is calling out Al Gore, the High Priest of the movement, on his lies.