The finding is prompting concerns that a new feedback loop that accelerates climate change may have already been triggered.

Russian scientists in the Arctic Ocean said they have discovered the most powerful methane gas fountain ever recorded, highlighting the danger of this greenhouse gas accelerating climate change or causing an oil or gas spill as it erupts from thawing permafrost.

Set against the austere peaks of the Western Brooks Range, the lake, looked like it was boiling. Its waters hissed, bubbled and popped as a powerful greenhouse gas escaped from the lake bed.

Gas bubbles from waters filling crater hole on Yamal peninsula two months after volcanic-style explosion in thawing permafrost.

On a rising tide, a line of bubbles from the mud under the water of Ugashik Bay can be observed rising forcefully to the surface.