Catastrophic methane release has been suggested as a possible cause of mass extinction. Methane clathrate is an ice-like substance formed from water and methane in the sea bed, arctic lakes and permafrost. It forms where the temperature is at freezing or a little above and where the pressure of overlying water and sediment creates the right conditions. A temperature rise causes the methane in the clathrate to be released as gas. Global warming results and causes further clathrate heating and methane release. The resultant soaring temperature causes such stress to plant and animal life that mass extinction follows.
Loose ends are tied up at last to explain the Permian mass extinction.
The Permian mass extinction was caused by two things: volcanic eruptions and methane release. This programme was first shown in 2002.
The clathrate gun hypothesis is the popular name given to the hypothesis that rises in sea temperatures (and/or falls in sea level) can trigger the sudden release of methane from methane clathrate compounds buried in seabeds and permafrost which, because the methane itself is a powerful greenhouse gas, leads to further temperature rise and further methane clathrate destabilization – in effect initiating a runaway process as irreversible, once started, as the firing of a gun.
In its original form, the hypothesis proposed that the "clathrate gun" could cause abrupt runaway warming in a timescale less than a human lifetime, and proposed responsible for warming events in and at the end of the last ice age. This is now thought unlikely.
However, there is stronger evidence that runaway methane clathrate breakdown may have caused drastic alteration of the ocean environment (such as ocean acidification and ocean stratification) and the atmosphere of earth on a number of occasions in the past, over timescales of tens of thousands of years; most notably in connection with the Permian-Triassic extinction event, when up to 96% of all marine species became extinct 252 million years ago.