Methane hydrates are thought to be responsible for between 5 and 10 million tonnes of methane emissions to the atmosphere each year. Globally, there are huge amounts of methane stored as hydrates. It is estimated that there is about 3000 times more methane locked up as hydrates than is currently to be found in our atmosphere.

Methane hydrates occur as solid deposits in marine sediments and in polar regions. They are made up of a mixture of methane and water (about 70% methane) which can quickly break down with changes in temperature and pressure to release the trapped methane.

The large scale breakdown of methane hydrate deposits has been blamed for huge underwater landslips and the creation of massive Tsunami waves in the Earth's history.

Human Impact

Methane hydrates represent one of the greatest potential dangers of human-induced global warming. With increasing temperatures large methane hydrates deposits may become unstable, threatening to cause freak and damaging waves. Furthermore, increased rates of methane release from hydrates to the atmosphere would further exacerbate global warming.

Potential for control

The hard to predict, but potentially catastrophic consequences, of global warming on the huge global deposits of methane hydrate underline the need for immediate action on man-made greenhouse gas emissions. Though there is little potential for direct control of methane emission from methane hydrates, limiting further global warming may be crucial to prevent a run-away scenario of methane release and warming.