Critical Oxygen Levels Threaten Earth's Life

Scientists predict that in about a billion years, Earth's atmosphere will revert to a methane-rich, low-oxygen state similar to before the Great Oxidation Event, which will likely end most oxygen-dependent life forms, although microbial life may persist. This future deoxygenation is driven by decreasing CO2 levels and increasing solar heat, with implications for understanding planetary habitability and searching for extraterrestrial life.