Permafrost soils store large quantities of organic carbon and are often portrayed as a critical tipping element in the Earth system, which, once global warming has reached a certain level, suddenly and globally collapses. Yet this image of a ticking timebomb, one that remains relatively quiet until, at a certain level of warming, it goes off, is a controversial one among the research community. Permafrost soils store large quantities of organic carbon and are often portrayed as a critical tipping element in the Earth system, which, once global warming has reached a certain level, suddenly and globally collapses. Yet this image of a ticking timebomb, one that remains relatively quiet until, at a certain level of warming, it goes off, is a controversial one among the research community. Earth Sciences Environment Phys.org – latest science and technology news stories