There is an enormous amount of methane (CH4) on earth frozen into a type of ice called methane hydrate. Hydrates can form with almost any gas and consist of a ‘cage’ of water molecules surrounding the gas. (The term ‘clathrate’ more generally describes solids consisting of gases are trapped within any kind of cage while hydrate is the specific term for when the cage is made of water molecules). There are CO2 hydrates on Mars, while on Earth most of the hydrates are filled with methane. Most of these are in sediments of the ocean, but some are associated with permafrost soils.
Methane hydrates would seem intuitively to be the most precarious of things. Methane hydrate melts if it gets too warm, and it floats in water. Methane is a powerful greenhouse gas, and it degrades to CO2, another greenhouse gas which accumulates in the atmosphere just as fossil fuel CO2 does. And there is a lot of it, possibly more than the traditional fossil fuel deposits. Conceivably, climate changes could affect these deposits. So what do we know of the disaster-movie potential of the methane hydrates?
David Archer is a computational ocean chemist at the University of Chicago. He has published research on the carbon cycle of the ocean and the sea floor, at present, in the past, and in the future. Dr. Archer has worked on the ongoing mystery of the low atmospheric CO2 concentration during glacial time 20,000 years ago, and on the fate of fossil fuel CO2 on geologic time scales in the future, and its impact on future ice age cycles, ocean methane hydrate decomposition, and coral reefs. Archer has written a textbook for non-science major undergraduates called “