"That said, most experts in the field suspect that all traditional sources (natural and anthropogenic) are contributing at least in small part to the surge, and

"That said, most experts in the field suspect that all traditional sources (natural and anthropogenic) are contributing at least in small part to the surge, and that the biggest contributor might be wetlands responding to climate change (though there is some dissent on this point)." New kind of clathrate gun we didn't anticipate?