2.19 > Gas hydrates occur when sufficient methane is produced by organic matter degradation in the sea floor under low temperature and high pressure conditions. These conditions occur predominantly on the continental margins. The warmer the water, the larger the ­water depths must be to form the hydrate. Deep inside he sea floor, however, the temperature is too high for the formation of methane hydrates because of the Earth’s internal heat.

Oxidation Many bacteria use methane to provide energy for their meta­bolism. They take up methane and transform it chemically. In this process the methane releases ­electrons and is thus oxidized. Some bacteria break the methane down with the help of oxygen. This is called aerobic oxidation. Other bacteria do not need oxygen. This kind of oxidation is called anaerobic.