From Huffington Post: http://www.huffingtonpost.com/2013/02/22/permafrost-melting-rate-2013_n_2741486.html
From Climate Central’s Michael D. Lemonick:
02/22/2013
Nearly a quarter of the Northern Hemisphere’s land surface is covered in permanently frozen soil, or permafrost, which is filled with carbon-rich plant debris — enough to double the amount of heat-trapping carbon in the atmosphere if the permafrost all melted and the organic matter decomposed.
According to a paper published Thursday in Science, that melting could come sooner, and be more widespread, than experts previously believed. If global average temperature were to rise another 2.5°F (1.5°C), say earth scientist Anton Vaks of Oxford University, and an international team of collaborators, permafrost across much of northern Canada and Siberia could start to weaken and decay. And since climate scientists project at least that much warming by the middle of the 21st century, global warming could begin to accelerate as a result, in what’s known as a feedback mechanism.
How much this will affect global temperatures, which are currently projected to rise as much as 9°F by 2100, is impossible to say. It all depends on how quickly the permafrost melts, and how quickly bacteria convert the plant material into carbon dioxide and methane gas, and nobody knows the full answer to that. But since climate scientists already expect a wide range of negative consequences from rising temperatures, including higher sea level, more weather extremes and increasing risks to human health, anything that accelerates warming is a concern.
While the rate at which melting permafrost will add carbon to the atmosphere is largely unknown, a study released February 11 in Proceedings of the National Academy of Sciences at least begins to tackle the problem. It shows that when the permafrost does melt, carbon dissolved in the meltwater decomposes faster after it’s been exposed to the ultraviolet component of sunlight.
In any case, there’s no doubt that the permafrost will melt, at least in part, since it’s already starting to do so. In some parts of the Arctic, trees, buildings and roadways have started listing to one side, or even collapsing, as soil that was once hard as a rock has softened from the warming that’s already taken place.
Continue reading at: http://www.huffingtonpost.com/2013/02/22/permafrost-melting-rate-2013_n_2741486.html
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