You're all overlooking the fact that
1) Fuck-US-Shima is still burning at 3MM plus degrees and has done considerable damage to the ozone over this long period of time (not to mention nuclear shit all over this planet). Burning the ozone then allows certain gases to advance to the next layer of the atmosphere which produces dichoric acid and heats the atmosphere ala methane...where does the methane come from?
2) Gulf where they initiated that little experiment. It's proven that the air from the Gulf flows right up into the Arctic. That air is full of massive amounts of methane that you can bet is not capped.

So there's your explanation of the "accidental" shit that has been carefully orchestrated...all by these bastards