what sea temperature is required for methane clathrate deposits to become unstable?

Question

at the present rate of temperature rise, when will this happen?
would a slow and gradual release over many millenia ameliorate its effects?
what would be the effect on global temperature of a sudden release?

Answer 1

I don't know much about the exact sea temperature required to de-stabilize methane hydrates, but from what I can gather, (a) the sea bed temperature would not have to rise too much, and (b) once started, the effect would trigger a catastrophic runaway greenhouse effect.

We might expect in a short period of time a climate similar to that which prevailed in the early Eocene, when the London /Thames Valley was submerged under a crocodile infested sea, steamy mangrove swamps covered the coastlines of Britain, and deciduous trees could grow in Polar regions (they evolved seasonal leaf fall to cope with the dark but balmy winter days!).

Answer 2

where you would find methane deposits in the sea the temperature always stays around 4 degrees C