In a groundbreaking simulation study, scientists at Japan’s Toho University have forecast a stark future for Earth: our planet’s oxygen-rich atmosphere could disappear in just one billion years, making life as we know it impossible. The study, conducted using NASA’s planetary modelling tools and published in Nature Geoscience, explored how Earth’s atmosphere will evolve as the sun ages and grows hotter.
What the Simulation Found
Researchers ran 400,000 simulations to model the long-term climate and atmospheric changes on Earth. The study predicts that around 1 billion years from now, Earth’s oxygen levels will plunge drastically. This deoxygenation will make complex life unsustainable, with ecosystems collapsing due to the absence of breathable air.
How and Why Will Oxygen Disappear?
As the sun gradually becomes hotter and brighter, it will:
Increase Earth’s surface temperatures
Cause more water to evaporate
Disrupt the global carbon cycle, killing plants
Halt photosynthesis, the primary source of atmospheric oxygen
Eventually, without plant life to produce oxygen, Earth’s atmosphere will revert to a state rich in methane—similar to conditions before the Great Oxidation Event over 2.4 billion years ago.
A Shift from Long-Held Beliefs
While earlier theories estimated that Earth’s biosphere might survive for two billion more years, this new model significantly shortens that timeline. The simulation suggests rapid oxygen loss will occur halfway through that period, radically changing life on Earth much earlier than expected.
According to lead researcher Kazumi Ozaki, the decline of oxygen will not be gradual throughout the entire two-billion-year span—it will be a sudden drop, leading to a fast and irreversible transition in atmospheric composition.
What Will Earth Be Like After Oxygen Is Gone?
Though life may still be possible in some form, it would look nothing like today’s biodiversity. The new atmosphere would be Rich in methane, Low in oxygen, Hostile to aerobic life, including humans and most animals.
This transformation would essentially return Earth’s atmosphere to its pre-oxygenated state, dominated by microbes capable of surviving in extreme environments.
A Glimpse Into Distant Future
This research provides new clarity on the long-term fate of Earth’s biosphere. While the oxygen crisis is still a billion years away, it offers valuable insights into:
How planetary atmospheres change over time
What to expect in the search for habitable exoplanets
The ultimate life span of oxygen-dependent ecosystems on Earth
The findings serve as a reminder of Earth’s place in the evolving cosmos and how even the most stable elements of our environment are subject to cosmic forces beyond our control.