Siberia is home to some of the coldest inhabited places in the world. But a few days ago, the small Russian town of Verkhoyansk recorded a temperature of 38C. It was a record high temperature locally and, probably, for the Arctic Circle. What made the heatwave all the more alarming, however, is that it is not a one-off.

While the world’s attention has been on the health and economic crisis wrought by the coronavirus pandemic, much of Siberia has been experiencing unusual heat. In May, surface temperatures in parts of the vast Russian region were up to 10C above average. The immediate consequences have been all too visible: accelerated melting of ice and snow, early outbreaks of large wildfires and a thawing permafrost.

What happens in Siberia matters to the rest of the world; the temperatures, together with above-average heat elsewhere, ensured that May 2020 tied with 2016 as the warmest May on record. There is an additional, alarming, effect from the Siberian heatwave: the thawing of the permafrost releases large amounts of carbon dioxide and methane into the atmosphere, promising to accelerate global warming.