Methane hydrates: formation, distribution, and climate implications

¶ … Methane Ices

Methane ice is crystalline solids which look like ice, and which occur when water molecules form a cage-like structure around smaller methane molecules producing methane ices (Thomas).

Researchers have known for a long time that a mixture of water and a gas such as methane, in the right circumstances, form an ice-like substance called a clathrate, or gas hydrate, at temperatures above normal freezing point (The Economist). The term 'clathrate' more generally describes solids consisting of gases that are trapped within any kind of cage, while hydrate is the specific term for when the cage is made of water molecules (Robertson).

How Did They Form?

Ice has an open molecular structure. Add a bit of pressure and that openness structure will accommodate gas molecules. These, in turn, lend support to ice crystals that would otherwise melt. Pressure is one of the things that the bottom of the sea is famous for. So, if you add a source of methane, conditions there are often ideal for the formation of methane ice (The Economist).

Methane ice occurs naturally wherever the conditions within the sediments are in the methane-clathrate stability field, and where methane and water are available (Thomas).

This stability is limited by temperature and pressure: gas hydrates are stable at low temperatures and/or high pressures. Because of the requirements of pressure and temperature, and because of requirement of relatively large amounts of organic matter for bacterial methanogenesis, methane ice is mainly restricted to two regions: high latitudes and along the continental margins in the oceans (Thomas).

What Impact may they have on Global Warming?

Key to understanding the gravity of climate destabilization is the wide array of catastrophic irreversible impacts that could amplify damage. One area of concern is methane hydrates ices (Robertson).

Methane hydrates can be destabilized by warming ocean temperatures. When they are destabilized, they release trapped methane into the oceans, and eventually into the atmosphere. Methane has 8 times the greenhouse effect as carbon dioxide, meaning a massive release would significantly accelerate climate change related to global warming (Robertson).

Today's concerns are focused on the potential harm from allowing any of the methane trapped in methane hydrates to escape into the atmosphere, whether from burning or melt-induced release (Robertson).

The accumulation of methane ice leads to ice ages and the rapid melting and effervescence of this ice and gas leads to an equally rapid global warming (Methane Hydrate Ice).