For nearly the first half of Earth's history, the planet's air and oceans were essentially oxygen-free.
Notes on verification
Confirmed by multiple independent, credible sources including science journalism outlets and press releases citing peer-reviewed research (Nature, Science). Timeline (Great Oxidation Event ~2.4 Ga) aligns well with 'nearly first half' framing given Earth's age of ~4.5 billion years.
Sources
- Interesting facts about Earth from Harvard paleontologist (news.harvard.edu)
- https://www.sci.news/othersciences/geoscience/great-oxidation-event-13012.html (sci.news)
- https://www.science.org/content/article/what-triggered-one-most-dramatic-changes-earth-s-history (science.org)
- https://www.whoi.edu/press-room/news-release/ocean-oxygenation/ (whoi.edu)