Abstract
What are the risks of a runaway greenhouse effect from methane release from hydrates in the Arctic? In January 2013, a dramatic increase of methane concentration up to 2000 ppb has been measured over the Arctic north of Norway in the Barents Sea. The global average being 1750 ppb. It has been suggested that methane normally trapped under the sea ice is now released more easily, especially in areas with reduced sea-ice extent. These high methane concentrations are possibly related to the destabilization of the methane gas hydrates in the Arctic shelf. Is this the start of a runaway greenhouse effect? Methane gas hydrates are solid, ice-like mixtures of water and methane. They are stable under relatively low temperatures and high pressures. These conditions can be found naturally in permafrost regions or under submarine continental slopes. Hydrates accumulate a large amount of gas. One cubic meter can include up to 160 m3 of methane. Their huge amount of stored energy and the wide geographical distribution make hydrates an attractive potential energy source. However, they are also suspected to be a source of global climate change and geological hazard, but the risk is still uncertain. Due to the quasi-stability of methane hydrates, any intervention in the temperature–pressure equilibrium could trigger hydrate dissociation followed by methane emissions, a runaway greenhouse effect, and potential underwater landslides. Here, some consequences for climate change of methane emissions to the atmosphere are analyzed in a scenario study.
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