Researchers from Toho University and NASA’s Nexus for Exoplanet System Science have utilized computer models to foresee that Earth’s oxygen-rich atmosphere will start to deteriorate in approximately one billion years. Their findings, published in Nature Geoscience, are presented by Kazumi Ozaki and Christopher Reinhard, detailing the simulation and outcomes. All experts concur that life on Earth is not eternal. Eventually, the Earth will meet its end when the sun depletes its fuel.
Experts have set a timeline for life as we know it
Rising temperatures will complicate survival long before that fiery fate becomes reality. The aim of this study was to pinpoint the precise moment when most plants and animals will be unable to thrive on Earth. They sought to identify the specific instant when life risks suffocation. In around a billion years, as the sun intensifies and emits more energy towards Earth, carbon dioxide levels are predicted to start diminishing. This decline occurs because CO₂ captures heat and eventually disintegrates. The ozone layer would also be severely affected and would deteriorate.
Given that plants rely on CO₂ for food production, they would struggle to survive as levels decline. Within about 10,000 years—a fraction of a blink in geological history—vegetation would completely vanish. Terrestrial and aquatic animals would also face extinction if plants ceased producing oxygen. Methane concentrations would rise, worsening the scenario and accelerating the extinction of oxygen-breathing organisms. Ultimately, the only life forms that would persist on Earth would be microscopic bacteria capable of surviving without oxygen—the same entities that existed prior to the emergence of larger plants and animals. Essentially, Earth would revert to its isolated microbial origins, completing a full cycle.
The study’s researchers emphasize that Earth’s oxygen-rich atmosphere has approximately 1.08 billion years left before it is depleted. For context, oxygen began accumulating in the atmosphere around 2.5 billion years ago during the Great Oxidation Event. It wasn’t until around 400 million years ago, when terrestrial plants began to evolve, that oxygen levels reached those comparable to today’s; prior to this, these levels were likely quite low throughout much of Earth’s history. Estimations suggest that Earth will remain habitable and retain surface water for about another 7.2 billion years. However, only about 20% to 30% of that time will be when the planet’s atmosphere is genuinely rich in oxygen.
Why is this significant? If we were searching the galaxy for signs of life, we would likely look for indicators such as ozone and oxygen in the atmospheres of other planets. If our telescopes had zeroed in on Earth two billion years ago or will focus on it two billion years in the future, we might not have detected these gases at all. Due to this misconception, we might overlook Earth’s breathable atmosphere during certain timeframes. This implies that even a thriving Earth could experience a “bad day” at some point, meaning the discovery of life may depend on spotting planets at the right moment.
Researchers have recently uncovered oxygen in a distant galaxy
Two expert teams conducted this study: one from the Scuola Normale Superiore University in Pisa, Italy, and another from the Leiden Observatory in the Netherlands. The European Southern Observatory indicates that nascent stars are primarily composed of light elements like hydrogen and helium. Heavier elements, such as oxygen, are synthesized by stars during their life cycles and subsequently dispersed across their galaxies upon their demise. Previously, scientists believed that a galaxy as young as JADES-GS-z14-0, which is merely 300 million years old, could not possibly contain oxygen.
