That is bad, bad news. Methane is what ancient anaerobic bacteria in the 'dead zones' of the oceans eat, which spew hydrogen sulfide. That will provide them a nigh limitless supply of food, and when bacteria have limitless food...

Well, I was hoping for a while that we could mine the methane hydrates, use them as an energy source. Burning it converts it into CO2, not good, but better than methane and waaaaay better than hydrogen sulfide. But it's too late for that, obviously; no time to ramp up infrastrucure for that now.

So, what are the choices? We could arm subs with powerful lasers and purposely detonate the methane hydrate deposits as they begin to dissociate (melt). That would produce some HUGE explosions. I kinda wonder if that wasn't what caused that Virginia quake. Not sure we have enough subs though. We could use nukes too, and that'd probably burn off the methane more effectively, but has the obvious drawback of needing to nuke most of the coastlines in the northern hemisphere (which is where most methane hydrate deposits are located).

Or we could just let the Earth do her thing, as she has before, and then we end up with a deadly poisonous and explosively flammable atmosphere for the next few million years.

Tough call there.