what we don't know
ABOUT PERMAFROST AND METHANE
Permafrost across the Tibetan plateau varies from frozen sub-surface soil to layers hundreds of metres underground. The Tibetan plateau comprises the largest sub-Arctic permafrost region on the planet. Frozen for millions of years, the permafrost is now in danger of thawing. It is not known how fast, but it is certain that permafrost thawing has been accelerated where human interference is a factor—such as the building of the railway line to Lhasa. By 'interference' here is meant the drilling of 7.6-metre-long steel tubes into the soil to act as 'cooling sticks', designed to refrigerate vulnerable parts of the soil along the railway tracks. These cooling sticks are filled with ammonia—to draw latent heat out of the soil.
In the process of thawing, permafrost could release large amounts of trapped carbon and methane. In permafrost regions, methane hydrate is found trapped in layers between 150 and 2,000 metres deep. As a greenhouse gas, methane is thought to be over 20 times more potent than carbon dioxide in its ability to trap heat in the atmosphere. It is not known what effect the release of large amounts of methane into the atmosphere would have. It would likely set in motion a vicious cycle of even more Earth warming—in turn triggering even more methane release.
Tibetan Plateau Permafrost:
(click to enlarge)