The article discusses the future of Earth’s atmosphere, predicting a return to a methane-rich, low-oxygen environment in about a billion years, similar to conditions before the Great Oxidation Event (GOE) 2.4 billion years ago. Researchers from Toho University in Japan highlight that the lifespan of Earth’s biosphere has been debated, focusing on the geochemical cycles of carbonate silicates and atmospheric CO2 levels as factors influencing global warming over geological timescales.
Models indicate a rapid decline in atmospheric oxygen, suggesting that oxygen-rich conditions are not permanent. This deoxygenation is significant, with predictions indicating oxygen levels could drop dramatically—about a million times less than present levels. The study emphasizes that as the sun’s brightness increases, photosynthetic organisms will diminish, leading to reduced oxygen levels.
This research is particularly relevant for the search for habitable exoplanets, as scientists may need to consider indicators beyond oxygen when assessing habitability. According to estimates, Earth’s oxygen-rich conditions may only account for 20-30% of its total lifespan. Eventually, the planet is expected to support anaerobic life forms in a methane-rich atmosphere characterized by low CO2 and no ozone layer. This study was published in Nature Geoscience.
