. . .

A major concern, a positive feedback loop: (note: approximately 3000 times the current volume of methane in the atmosphere is currently stored in hydrate form).

 

Note, however, that "catastrophic" release of CH₄ during period of Ice Ages may be the natural way that the Earth accelerates out of a glacial period. There is lots of evidence discovered in the last 2-3 years for such sudden warm ups in geologic history.

Known Hydrate deposits. Found typically in continental shelf where marine organisms (microbes) actively feed on carbon and carbon related productes to produce methane in the sediments.

Methane is more directly related to food production and population growth so it could also dominate in the near future