'Sleeping giant' Arctic methane deposits starting to release, scientists find

Exclusive: expedition discovers new source of greenhouse gas off East Siberian coast has been triggered

Scientists have found evidence that frozen methane deposits in the Arctic Ocean - known as the sleeping giants of the carbon cycle" - have started to be released over a large area of the continental slope off the East Siberian coast, the Guardian can reveal.

High levels of the potent greenhouse gas have been detected down to a depth of 350 metres in the Laptev Sea near Russia, prompting concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global heating.