Following on its coverage of an expedition to Russia's northern coast that found methane deposits leaking through melting permafrost into the water and atmosphere, The Independent has news that a British expedition to the seas off the coast of Norway has discovered "hundreds of methane plumes". From the article:
Yesterday, researchers on board the British research ship the James Clark Rosssaid they had counted about 250 methane plumes bubbling from the seabed in
an area of about 30 square miles in water less than 400 metres (1,300 feet)
deep off the west coast of Svalbard. They have also discovered a set of
deeper plumes at depths of about 1,200 metres at a second site near by.
The story notes that "It is likely that methane emissions off Svalbard have been continuous for about 15,000 years – since the last ice age." I think it is fascinating that these plumes have only just been discovered. This means the methane budget of the atmosphere is probably still quite poorly understood, even as it is clear new sources of methane are opening due to climate change.