Want an oxygen-rich atmosphere? Stuff oxygen’s friends in the mantle.

A PNAS study says Earth’s oxygen-rich atmosphere was shaped by cold subduction deep in the planet.

As supercontinents formed and broke apart, more efficient plate tectonics buried carbon- and sulfur-rich sediments in the mantle.

That reduced the return of these materials to the surface, helping oxygen accumulate in the atmosphere over time.

The finding links long-term oxygen buildup to deep-Earth tectonics and the conditions that made complex life possible.