Three-hundred-million years ago, the planet repeatedly lost control of its carbon cycle and suffered 90m years of mass extinctions, including two of the biggest global catastrophes of all time – both CO2-driven nightmares. In one case, it nearly died. It was felled, in the words of the palaeontologist Paul Wignall, by “a climate of unparalleled malevolence”. At the very end of the Permian period (252m years ago), enough lava erupted out of Siberia and intruded into the crust that it could have covered the lower 48 US states a kilometre deep.

A kilometre deep.

(,,,) the best estimate is that we’re emitting carbon perhaps 10 times faster than even the mindless, undirected Siberian volcanoes that brought about the worst mass extinction ever.