Scientists have found out when Earth might lose its oxygen atmosphere

There are several possible reasons for the disappearance of life on Earth, including climate change, rising carbon dioxide levels, asteroid impacts, and the gradual increase in the Sun's luminosity. However, in this case, researchers focused on another process – the future loss of oxygen in the atmosphere.

Approximately 2.5 billion years ago, the so-called Great Oxygenation Event occurred. During this period, oxygen levels in Earth's atmosphere and oceans significantly increased. It is believed that single-celled organisms played a key role in this, although the exact causes of the event are still debated by scientists. The accumulation of oxygen became an important stage in Earth's evolution and allowed numerous complex forms of life to develop.

Researchers Kazumi Ozaki from Toho University and Christopher Reinhard from the Georgia Institute of Technology created a computer model of Earth that accounted for climatic and biochemical processes. The study was published in the scientific journal Nature Geoscience.

Scientists conducted 400,000 computer simulations, each time varying different parameters of the model. As a result, they concluded that Earth's oxygen atmosphere will persist for approximately the next billion years.

After that, according to the modeling, a rapid deoxygenation of the atmosphere will occur. It will become similar to the atmosphere of early Earth, which existed before the Great Oxygenation Event.

After a sharp decrease in atmospheric oxygen levels, there will be more methane, and little carbon dioxide will remain. The ozone layer will also disappear. Researchers suggest that Earth will transform into a world dominated by anaerobic life forms, capable of existing without oxygen.

Previously, scientists believed that Earth's biosphere could exist for about two billion years. This was linked to the gradual increase in the Sun's luminosity, global warming, and a decrease in the amount of carbon dioxide needed by plants for photosynthesis. The new study allows for a more accurate estimation of the possible duration of the oxygen atmosphere's preservation, although predictions spanning billions of years carry significant uncertainty.

The results of the study are important not only for understanding the future of our planet but also for the search for life beyond the Solar System. Oxygen is considered one of the possible biosignatures – chemical substances in a planet's atmosphere that can indicate the existence of biological processes.

However, an oxygen-rich atmosphere is not a permanent sign of life on a planet. According to researchers, it may persist for only 20-30 percent of Earth's history. Therefore, astronomers should also look for signs of life on planets with low oxygen content or its complete absence. This could increase the chances of detecting extraterrestrial life.

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