Biogenic methane is formed by bacterial activity in sediment. This is the most common way that methane is formed. Thermogenic methane is formed when oil reservoirs beneath the sea floor get too hot and pressurized. When methane reaches the seabed through passages provided by geologic faults, it is either contained in ice forms called hydrates, or released into the water and then into the atmosphere, where it may cause damage to the environment. Hydrates hold about 160 times more methane than if the gas were in its free form.
Gas hydrates form and become stable when water reaches a certain temperature and pressure.
As water warms or as pressure decreases, hydrates become unstable and break down, releasing the gas in a process that can be harmful to the atmosphere. Methane contributes to the greenhouse effect 20 times more than carbon dioxide does, Aharon said. If the Earth's oceans warm up as they are predicted to with global warming, increasing amounts of hydrates will become unstable and release methane. The release of gas would contribute to further global warming, and a dangerous cycle would begin. Aharon's research focuses on this cycle and on what has happened to hydrates in the past.