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Siberia's melting permafrost fuels climate change Thawing permafrost is releasing greenhouse gases, ruining buildings, and may even be creating massive sinkholes. Lowana Veal | 23 Nov 2015 13:46 GMT | Environment, Climate Change Frost mound in Reindalen, Svalbard formed as permafrost confines groundwater, which is pushed on the surface under hydrostatic pressure and freezes [Alfred Wegener Institute/Jaroslav Obu] Reykjavik, Iceland - Over the past year, a number of giant, mysterious holes have emerged in Siberia, some as deep as 200 metres. Scientists say the craters may be emerging because the frozen ground, or "permafrost", that covers much of Siberia has been thawing due to climate change, allowing methane gases trapped underground to build up and explode. Permafrost is ground that is permanently frozen, where the ground temperature has remained below zero degrees Celsius for at least two years. It covers about a quarter of the northern hemisphere's land surface. When permafrost thaws, microbes digest the plant and animal remains that were locked in the permafrost and release greenhouse gases, carbon dioxide and methane into the atmosphere. The phenomenon is a self-feeding cycle, explained Sarah Chadburn, from the University of Exeter.