Alaska’s permafrost may begin to thaw before the end of the century

BBC : Permafrost, soil that has been below 0 °C for at least two years, covers about 25% of the Northern Hemisphere near the Arctic and is also found in the Antarctic and in some mountain regions. It ranges from just the top 1 m of soil to depths of up to 1500 m. Trapped in the soil is methane gas; some estimates put the volume of gas as twice the amount of carbon currently in the atmosphere. Vladimir Romanovsky of the University of Alaska Fairbanks and the Global Terrestrial Network for Permafrost has found that the permafrost in northern Alaska has been warming at one-tenth of a degree per year since the mid 2000s. If that rate continues, Romanovsky says it could thaw as soon as 2070. The warming has already caused trees to topple, roads to buckle, and sinkholes to form. If the permafrost melts completely, much of the methane would be released and would exacerbate the effect of growing levels of greenhouse gases.