When people think of the end of the world, they often imagine cataclysmic events—asteroids, nuclear war, or sudden climate collapse. But according to a groundbreaking joint study by NASA and Japan’s Tōhō University, Earth’s real doomsday won’t come in a dramatic explosion, but in silence—as the planet slowly runs out of oxygen.
Using advanced supercomputer simulations, scientists project that by the year 1,000,002,021, Earth will no longer be able to support complex life. The reason? Not external impact, but a gradual transformation caused by the Sun’s evolution, disrupting Earth’s atmosphere and stripping it of oxygen, the very foundation of all known animal life.
Supercomputer Simulations Reveal Earth’s Slow Death
This scientific forecast is based on simulations that track atmospheric and biological interactions over geological timescales. The models, led by Kazumi Ozaki from Tōhō University and Christopher Reinhard from Georgia Institute of Technology, include variables such as ocean chemistry, carbon cycles, and solar radiation.
“We found that Earth’s oxygen-rich atmosphere is not a permanent feature,” said Ozaki. “Eventually, the biosphere will collapse due to a lack of oxygen.”
Their models show that the decline may begin as soon as 10,000 years from now, and by the billion-year mark, oxygen will fall to levels too low to sustain animals and plants.
The Sun: Life-Giver Turned Life-Taker
At the core of this scenario is the Sun. As it ages, the Sun’s brightness and energy output will increase. This increase will destabilize the carbon dioxide levels in Earth’s atmosphere. Since CO₂ is vital for photosynthesis, plants will lose their ability to generate oxygen.
Without photosynthesis, oxygen production halts, and Earth’s oxygen supply dwindles. As Reinhard noted, “Oxygen loss is an inevitable consequence of solar evolution. We may be closer to the end of Earth’s habitability than we thought.”
A Return to a Primitive Atmosphere
Without plants and photosynthesis, the ozone layer will disappear, removing the shield that protects life from ultraviolet radiation. UV rays will hit Earth’s surface directly, making it extremely hostile—even for microbes.
At the same time, the atmosphere will begin to resemble Earth’s ancient past: dominated by methane and nitrogen, instead of oxygen. It will mirror the toxic conditions of early Earth before the Great Oxidation Event more than 2 billion years ago. In such an environment, only anaerobic bacteria—microbes that do not need oxygen—might survive.
Yet even these microbes will face extinction as temperatures rise and UV radiation intensifies. This transition marks the final stage in Earth’s habitability: a once-living world, now barren and breathless.
Confirmed by Models and Planetary Data
This is no mere theoretical thought experiment. The study integrates a wide array of real-world data—from geological records to atmospheric models and solar physics.
Recent space weather events like powerful solar storms, which briefly disrupted Earth's magnetic field, have already offered minor previews of how solar activity can influence atmospheric stability. These short-term events offer validation of the long-term processes predicted by the models.
Humanity’s Options: Adapt or Leave?
While the end is billions of years away, the beginning of this decline could be visible to future generations. The study urges serious consideration of technological adaptation and planetary migration. From building sealed biospheres to terraforming Mars, researchers believe we must prepare for Earth’s eventual loss of habitability.
NASA, ESA, and private companies like SpaceX are already advancing missions focused on long-term space habitation. These efforts gain renewed relevance as studies like this highlight the finite lifespan of our biosphere.
“This is not just about Earth,” said Reinhard. “It’s about understanding the limits of planetary life—and what it takes to extend it elsewhere.”
Changing How We Search for Habitable Planets
This research also shifts how we search for life beyond Earth. Traditionally, oxygen has been considered a key biosignature in exoplanet exploration. But if oxygen is only present for a fraction of a planet’s life, we may need to broaden our criteria.
Scientists are now considering other atmospheric gases like methane or ammonia, as well as indirect indicators of microbial activity. The quest to find another “Earth” becomes more complex—and more urgent.
References:
- Ozaki, K., & Reinhard, C. T. (2021). The future lifespan of Earth’s oxygenated atmosphere. Nature Geoscience, 14(2), 138–142. https://doi.org/10.1038/s41561-020-00693-8
- Ferguson, M. (2025). NASA and Tōhō University Predict Earth’s Distant Doomsday. OpenTools & 3DVF.
- Edwin O. (2025). Earth Is Running Out of Oxygen — Experts Already Talk About This Date. The Cleveland American.
- El Adelantado. (2025, May 12). NASA confirms that the end of life on Earth will be due to loss of oxygen. https://eladelantado.com/news/earth-oxygen-loss-nasa-study/
