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Editor’s summary

Only a few of the many volcanism-driven hyperthermals during the Phanerozoic caused mass extinctions, and none of them approached the level of global species loss seen at the end of the Permian. Why was the end-Permian so different? Sun et al. found that a combination of extreme El Niño events and mean state warming led to deforestation, reef demise, and a plankton crisis, all of which resulted in a positive feedback cycle that led to an even warmer mean climate and still stronger El Niño events. —Jesse Smith

Abstract

The ultimate driver of the end-Permian mass extinction is a topic of much debate. Here, we used a multiproxy and paleoclimate modeling approach to establish a unifying theory elucidating the heightened susceptibility of the Pangean world to the prolonged and intensified El Niño events leading to an extinction state. As atmospheric partial pressure of carbon dioxide doubled from about 410 to about 860 ppm (parts per million) in the latest Permian, the meridional overturning circulation collapsed, the Hadley cell contracted, and El Niños intensified. The resultant deforestation, reef demise, and plankton crisis marked the start of a cascading environmental disaster. Reduced carbon sequestration initiated positive feedback, producing a warmer hothouse and, consequently, stronger El Niños. The compounding effects of elevated climate variability and mean state warming led to catastrophic but diachronous terrestrial and marine losses.