sub-ocean methane leaking

I'm surprised this news hasn't gotten more coverage: there's preliminary news that, as the permafrost is melting, methane that was previously trapped beneath the Arctic Sea is bubbling to the surface and escaping to the atmosphere. Methane is about 20 times as powerful a greenhouse gas as carbon dioxide. It's not yet clear just how much methane is escaping, but it does raise the concern of a positive feedback loop, where more methane escapes, warms the climate, causing more permafrost melting, more methane escaping, and so on.