“Volcanoes are not entirely off the hook,” writes Chandler. “They have simply been demoted to accessories to the crime. The reason for the sudden, explosive growth of the microbes, new evidence shows, may have been their novel ability to use a rich source of organic carbon, aided by a sudden influx of a nutrient required for their growth: the element nickel, emitted by massive volcanism at just that time.”

The burst of methane would have increased carbon dioxide levels in the oceans, resulting in ocean acidification — similar to the acidification predicted from human-induced climate change. Independent evidence suggests that marine organisms with heavily calcified shells were preferentially wiped out during the end-Permian extinction, which is consistent with acidification.”