New research published in Nature Communications sheds light on how Earth kept oxygen in the atmosphere after the Great Oxidation Event over 2 billion years ago. Scientists led by UC Riverside's Andrey Bekker found that phosphorus recycling in ancient oceans created a self-sustaining cycle that maintained oxygen levels. By separating biologically available phosphorus from mineral-bound forms in rocks from South Africa, they showed that sulfate from oxygen allowed microbes to break down organic matter more efficiently, releasing phosphorus that fueled more life and more oxygen production. The findings also suggest oxygen levels swung more dramatically than previously thought, which may have influenced early life evolution. The study has modern relevance: as climate change deoxygenates the oceans, phosphorus availability could decline, reducing marine productivity and making ecosystems less resilient. Understanding these ancient cycles helps scientists model future ocean health and the search for habitable exoplanets.
