New research published in Nature Communications explains how early Earth kept enough oxygen in the atmosphere to support life after the Great Oxidation Event around 2.3 billion years ago. Scientists studied rock samples from South Africa and found that oxygen entering the oceans increased sulfate levels. Microbes used that sulfate to break down organic matter more efficiently, which released phosphorus back into the water. More phosphorus meant more biological productivity and more organic carbon buried in seafloor sediments. That burial reduced oxygen consumption and created a feedback loop that sustained atmospheric oxygen. Researchers say the findings also suggest oxygen levels fluctuated after the Great Oxidation Event rather than staying steady. That matters for understanding why complex life appeared so late, and for modern ocean health. Climate change is already cutting oxygen in parts of the ocean, and further loss could disrupt phosphorus recycling and reduce marine productivity.
