Hum,
The deep sea water Calthrates were probably layed down during the last ice age...within the time scale of less than 50,000 years…
These small pockets of gases are formed in low temperature, high pressure, environments.
When the temperature is increased as it has done so, these pockets are disrupted and the methane will rise into the atmosphere, causing increased temperatures which further increase the release of methane.
Btw, I sure that those old sea dog stories of falling off the sea were just political and economic propaganda to stop others from exploiting trade routes…
