From Lab to Life: How Earth Sustained Its Oxygen

Life on Earth exists, because there is oxygen in the atmosphere. We know how it began. Cyanobacteria figured out how to crack CO₂  into carbon and oxygen, using sunlight, and single cells figured out how to ‘swallow’ cyanobacteria and incorporate their unique skills to produce photosynthesis, which supported plant life.

But how did the world maintain its oxygen?

This new study, reported by Science Daily, reports on new findings to help explain it. **

** Lewis J. Alcott, Benjamin J. W. Mills, Andrey Bekker, Zidong Peng, Simon W. Poulton. A nutrient control on oxygenation dynamics during Earth’s Great Oxidation Episode. Nature Communications, 2026; 17 (1) DOI: 10.1038/s41467-026-76597-y

“Ancient rocks reveal that phosphorus recycling in the oceans created a self-sustaining cycle that helped keep oxygen levels high, even as the planet underwent dramatic environmental changes. The discovery challenges assumptions about Earth’s early atmosphere and raises new questions about why complex life took so long to emerge.”

The research was done by scientists at the University of California—Riverside. It turns out that our oceans played a key role.

“More than 2 billion years ago, Earth underwent a dramatic transformation as oxygen began building up in its atmosphere. But that change left scientists with a major mystery: How did the planet maintain enough oxygen to remain habitable over millions of years?

“Researchers have now uncovered evidence that the answer may lie in an ancient recycling system within Earth’s oceans. By studying rocks from South Africa, they found that changes in ocean chemistry helped create a natural cycle in which biological activity supported the continued accumulation of atmospheric oxygen.

“The research, published in Nature Communications, involved scientists including University of California, Riverside geologist Andrey Bekker. Their findings suggest that phosphorus, a nutrient essential for life, played a central role in sustaining the oxygen levels that would eventually help make more complex organisms possible.”

Here is how the researchers think the process worked:

“The researchers identified a feedback loop that may help explain what happened. As oxygen spread into the oceans, it altered the chemistry of seawater and increased concentrations of sulfate, a compound containing sulfur and oxygen.  Certain microbes used this sulfate to break down organic material more efficiently. In the process, they released phosphorus back into the water, making this vital nutrient available to other organisms. With more phosphorus available, biological productivity increased. That meant more organic carbon could eventually become buried in seafloor sediments rather than being broken down. Because the decomposition of organic matter can consume oxygen, burying more carbon helped favor the continued buildup of oxygen in the atmosphere.” 

Could this same process be occurring as we speak, on other planets?