Common throughout the Arctic and Antarctic – and in some high-altitude regions such as the Tibetan plateau – permafrost is frozen soil that has been at a temperature below freezing all year round for at least two years.
It is estimated that the frozen organic matter trapped in these icy soils contains more carbon than the total amount now in the atmosphere.
As the world warms and permafrost thaws, this organic matter starts to decompose, releasing greenhouse gases such as carbon dioxide and methane which go on to further increase global temperatures.
New research by English, Swedish and Norwegian researchers, published today in Nature Climate Change, suggests that each degree of warming the Earth undergoes will cause an additional 4 million km2 of permafrost – an area larger than India – to thaw.
