Additionally, a potentially bigger risk is if there is a massive methane release event, it could drastically accelerate global warming.

Methane traps up to 100x more heat in the atmosphere than an equivalent amount of CO2 (over a 5 year period) and 72x more heat over a 20 year period

Source: http://www.onegreenplanet.org/animalsandnature/methane-vs-ca...