Giant craters on the Arctic sea floor were formed when methane gas previously trapped in ice was released with such force it blew through bedrock, Norwegian researchers say. "To disturb the bedrock that much, we feel pretty certain that it's not something that can be done by gas bubbles just seeping up. This August 2009 photo shows methane gas bubbles in the Mackenzie River Delta in the Northwest Territories. Whether the phenomenon also pushes greenhouse gases out of the water and into the atmosphere is an area requiring further research, the Norwegian study says. But the Beaufort Sea shelf is more shallow, he said, so it's possible for methane bubbles to reach the atmosphere.

Source: CBC News June 02, 2017 09:00 UTC