Naturally occurring forest fires, especially in warm and dry years, also release methane into the air. (discovermagazine.com)
And the structures that remain apparently release methane gas for some time — as is evidenced by continued high methane concentrations found at crater sites and by observed emissions from crater lake surfaces. (robertscribbler.com)
However, the breakdown of organic matter in wetlands can also release methane, a much more potent greenhouse gas. (eos.org)