A new collaborative study conducted by NASA and Japan’s Toho University offers a glimpse into Earth’s distant future. It reveals that our oxygen-rich atmosphere, critical for complex life, won’t last forever.
Earth’s atmosphere is rich in oxygen, which signals the presence of life. However, it’s unclear how long this oxygen-based signature will last. Scientists now estimate that this breathable air will persist for about one billion more years before a dramatic shift alters the planet’s habitability.
According to their findings, the long-term interplay between solar radiation, atmospheric chemistry, and geological processes will gradually erode Earth’s ability to sustain high oxygen levels. As the Sun continues to brighten with age, increased energy from solar radiation will accelerate the breakdown of carbon dioxide, reducing its availability for photosynthetic life forms. As a result, plants will struggle to survive, leading to a steep decline in oxygen production.
Using advanced climate and biogeochemical modeling, researchers ran more than 400,000 simulations to predict the timing of this atmospheric shift. The findings indicate that Earth’s oxygen-rich environment is a temporary phase in its history, lasting just 20–30% of its total lifespan as an inhabited world.
After deoxygenation, Earth’s atmosphere will resemble its ancient past, characterized by elevated methane levels, diminished carbon dioxide, and no protective ozone layer. This transformation will make the planet inhospitable to most modern life forms, leaving microbial ecosystems adapted to low-oxygen conditions behind.
Beyond its implications for Earth’s future, this discovery significantly impacts the search for extraterrestrial life. Oxygen is widely recognized as a biosignature for habitable exoplanets, but the study suggests that a planet’s oxygen-rich phase may be fleeting. Scientists will need to consider additional life markers—especially for worlds in transitional atmospheric states—as they hunt for signs of habitability beyond the solar system.
While humanity won’t witness this transformation firsthand, understanding Earth’s evolving atmosphere offers valuable insights into planetary life cycles, helping researchers refine methods for detecting biosignatures on distant worlds.
Journal Reference:
- Ozaki, K., Reinhard, C.T. The future lifespan of Earth’s oxygenated atmosphere. Nat. Geosci. 14, 138–142 (2021). DOI: 10.1038/s41561-021-00693-5
