The largest frozen peat bog in the world, lying in western Siberia, is melting, according to Russian scientists. The million square kilometre area*, previously permafrost, is becoming a series of increasingly soggy shallow lakes, some already more than a kilometre across.

The melting raises the spectre of vast quantities of methane suddenly being released into the atmosphere. Methane is one of the most potent greenhouse gases, with a warming effect 20 times greater than that of carbon dioxide.

The researchers, Sergei Kirpotin, a botanist at Tomsk State University, Russia, and Judith Marquand at the University of Oxford, told New Scientist that the whole western Siberian sub-arctic region has begun to melt, and that this has only happened in the last four years. Kirpotin said he had witnessed an "ecological landslide that is probably irreversible and is undoubtedly connected to climatic warming".

The frozen peat bogs formed at the end of the last ice age, around 11,000 years ago. One thing peat bogs do is produce methane, a byproduct of rotting organic material. However, since Siberia has been frozen, most of the methane generated over the last 11,000 years has been trapped in the permafrost.

Now that it is melting, and provided the region stays wet, all that methane will be released into the atmosphere. If the bogs dry out, the methane will have a chance to oxidise to form carbon dioxide before it escapes the bogs, which would lessen the impact.

Siberia is particularly vulnerable to climate change, it seem, and the region has warmed faster than anywhere else on the planet. A positive feedback cycle is created when ice melts, exposing more ground which absorbs more solar energy than ice or snow. This, in combination with regional weather shifts, such as the Arctic oscillation, is thought to be behind the region's three degree increase in average temperatures over the last 40 years. ®

Bootnote

*Almost 50 times the size of Wales, for those who like to keep track of these things

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