The Earth’s current atmosphere, rich in oxygen, is essential for the survival of complex life. However, scientists predict that in about a billion years, atmospheric conditions will shift back to methane-rich and low-oxygen levels, reminiscent of the planet before the Great Oxygenation Event (GOE) around 2.4 billion years ago. This significant transition may occur rapidly, as highlighted in a 2021 study involving models of the Earth’s biosphere.
Muzumino Waguchi from Toho University emphasized that continuous carbon dioxide declines and warming, influenced by the sun’s brightness, will lead to this deoxygenation. The study suggests that as atmospheric oxygen dramatically decreases—potentially to levels a million times lower than today—most life forms, particularly those reliant on oxygen, will perish long before significant seawater loss occurs.
Researchers modeling these changes noted that with decreasing CO2, photosynthetic organisms will dwindle, further reducing oxygen levels. This emphasis on oxygen depletion is crucial for understanding habitable conditions on other planets, as indicated by the NASA Nexss project. Insights from the study suggest oxygen-rich conditions may only last 20-30% of Earth’s total lifespan, ultimately giving way to an environment dominated by anaerobic life forms. This research was published in Nature Geoscience.
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