At the end of the Permian, Siberia would turn inside out, burbling lava over millions of square miles and swamping the atmosphere with volcanic gases. One gas in particular stands out as the primary killer in what would become the greatest mass death in earth history. Researchers don’t study the worst catastrophe ever purely out of academic, or even morbid, curiosity. The End-Permian mass extinction is the absolute end-member—the worst-case scenario—for what happens when you jam too much carbon dioxide into the atmosphere.
