I’ve read about frozen methane deposits that lie off California’s coast. How is this possible? These deposits exist at 2000m (or ft, I forget how deep they are). Is the ocean really cold at that depth? How does the ocean manage to trap methane and freeze it? Would this methane still be frozen if it were brought to the surface? Could I hold the deposits in my hand (I assume they’re solid; correct me if I’m wrong).
Methane hydrate is solid bcause of the pressure–more precisely, it’s cold enough at depth to keep it frozen at the pressure down there. If you try to bring it to the surface, the methane boils away. This is one theory of why the Permean Extinction 250 million years ago was so bad; it is thought by some that a global termperature rise caused by some combination of vulcanism and/or asteroid impact raised the sea temps enough to thaw out huge amounts of submarine methane hydrates releasing methane ( a powerful greenhous gas) into the atmosphere to further raise the golbal temperature. Double whammy.
Also, and perhaps more importantly, the global temperature. The golbal temperature is only really important to the golbs and if they bitch about it, well, they can just go pound sand.
Q, you just scared the shit out of me. How much would the mean temperature have to rise for significant quantities of frozen methane to start bubbling up?
IIRC, the temperature rise needed to start unthawing large amounts of methane hydrates was calculated to have been around 5 degrees C. The atmospheric methane was then believed to have been responsible for an additional 5-degree rise.
I understand (perhaps wrongly) that these are crystaline structures which would be very tricky to harvest without causing undersea collapses but there is enough energy there to forget about oil.
If anyone needs me, I’ll be in my bunk…er.
Let me be the first to welcome our new golbal overlords.
And that methane release/temperature rise will give birth to more and more severe storms – even a Mother of Storms.
That would, of course, be the sand found in the Golbi Desert? 
I sometimes encounter methane hydrate at work. We’ll open up a gas well and chunks of frozen methane hydrate will fall out and sit on the ground and hiss, bubble and boil away to nothing.
I’ve seen video of “burning ice” - a chunk of methane clathrate with the methane burning away and the water melting. The Wikipedia article has a cool picture, too.
There is a theory that sudden methane release may be responsible for some ship sinkings in places like the North Sea or the Bermuda Triangle. A large volume of clathrate melts, releasing methane. The methane bubbles round the ship (or the ship sails into the bubbling region), reducing the density of the water (and thus the buoyancy), and the ship goes straight down in seconds - no warning, no alarm.
Harvesting these clathrates could provide energy for years to come, but the technical problems to be overcome have so far prevented anyone from harvesting the energy available. And doing so while avoiding the risk of a catastrophic release of methane (either as a greenhouse gas in the upper atmosphere or as a fuel-air explosive when it catches alight at the surface) into the atmosphere adds significantly to the complexity.
Si
The Straight Dope on methane under the sea:
So what happens if global warning melts the methane? how much can the temperatures rise? and how much will it take to make the planet inhabitable?