Methane Discovered Bubbling Up From Arctic Sea Floor
Scientists have discovered the potent greenhouse gas methane seeping from the from the floor of the Arctic Ocean off Spitsbergen, Norway, the BBC reports. Writing in Geophysical Research Letters, the researchers say they did not expect to discover this predicted positive feedback of climate change already beginning: 
Plumes Found at Deeper Depths as Ocean WarmsThe scientists have discovered more than 250 plumes of methane, at depths of 150-400m. The gas is normally trapped as methane hydrate, and kept stable by low temperature and high pressure. So far it doesn't appear that the methane is breaking the surface and getting into the atmosphere, but the researchers say they don't out this happening in the future.
In the past 30 years the ocean has warmed 1°C in the area being studied. At the beginning of that period, data shows that methane hydrate was stable at depths of 360m.
Tens of Megatons Could Be ReleasedThe BBC quotes Graham Westbrook, professor of geophysics at University of Birmingham on the future implications of this discovery:
If this process becomes widespread along Arctic continental margins, tens of megatons of methane a year -- equivalent to 5-10% of the total amount released globally by natural sources -- could be released into the ocean.Atmospheric Methane Levels Rising AgainThough atmospheric methane levels had remained stable for nearly a decade, last October it was discovered that they were rising again. One suspected cause is increased melting of Siberian permafrost, where the gas is normally kept stable frozen in the ground.
More: BBC Newsphoto and map: WikipediaMethane Major Source of Atmospheric Methane Identified Near Arctic LakesMethane Extracted from 'Ice' + Carbon Sequestration = Green Fossil Fuel?Permafrost Holds Twice as Much GHGs as Previously Thought: Over 1500 Billion Tons of CO2 and Methane
