In some places this has pushed the temperature above freezing, meaning soils that may have been frozen for thousands of years begin to decompose and release their carbon. Scientists are worried about the potential for a ‘climate feedback loop’ being created, whereby warming generates emissions which generate more warming and so on.

“The melting of glaciers is a consequence of climate change,” said Dr Steve Gurney, a geomorphologist at Reading University. “But thawing permafrost is a cause not a consequence. The pool of carbon in permafrost is absolutely massive and the more we look at it, the bigger we find it is.”

McGuire’s study found that increasing global temperatures would cause “a gradual and prolonged release of greenhouse gas emissions” from the permafrost.