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.
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.