Splintered continents help keep a lid on global warming

Every so often Earth's volcanoes come to life in spectacular fashion. Geologists have uncovered ten of these dramatic magma-spewing episodes to date. At least four are thought to be behind mass extinction events, including Earth's most devastating extinction at the end of the Permian period around 250 million years ago. But strangely life on Earth sailed through the most recent eruptive episode, around 60 million years ago, seemingly unscathed. Now a new book sheds light on why some volcanic outpourings are so much more catastrophic to life than others.

In The Worst of Times, Paul Wignall, a geologist at the University of Leeds, explores the connection between supercontinents and mass extinctions. At the end of the Permian, Earth's landmasses were joined into one huge continent, called Pangea. When the volcanoes began to erupt, across what is now Siberia, they spewed out enough lava to cover an area the size of western Europe. The resulting global warming and ocean acidification wiped out 90% of all species. By contrast, the most recent outpouring of lava, in the North Atlantic around 60 million years ago, caused some global warming, but failed to bring about a mass extinction event.