“Scientists Predict Earth’s Atmosphere Will Revert Back to Methane-Rich, Oxygen-Poor State In The Future”
New research published in 2021 suggests that in the future, Earth’s atmosphere will transition back to a state rich in methane and low in oxygen, similar to conditions before the Great Oxidation Event around 2.4 billion years ago.
While this shift isn’t expected to occur for another billion years or so, the research indicates that the change will happen fairly rapidly once it begins. This has significant implications for the future of life on Earth and our understanding of habitable worlds in the Universe.
The study, published in Nature Geoscience, used detailed models of Earth’s biosphere to predict the deoxygenation of the atmosphere. The researchers factored in changes in the brightness of the Sun and the corresponding decrease in carbon dioxide levels, which would lead to a reduction in oxygen due to fewer photosynthesizing organisms such as plants.
According to the researchers, this significant drop in oxygen levels could precede the loss of ocean waters from our planet, ultimately leading to the end of life as we know it. Earth scientist Chris Reinhard noted, “We’re talking around a million times less oxygen than there is today.”
The findings also have implications for our search for habitable planets outside of the Solar System. With the possibility that oxygen may not be a permanent feature of habitable worlds, scientists may need to look for other biosignatures to detect signs of life.
The study is part of the NASA NExSS (Nexus for Exoplanet System Science) project, which explores the habitability of planets beyond our own. The researchers estimate that Earth’s oxygen-rich habitable history may only last for 20-30 percent of the planet’s lifespan, with microbial life continuing to exist long after the atmosphere transitions to an anaerobic state.
As we continue to explore the Universe and search for signs of life, these findings highlight the importance of understanding the potential changes in planetary atmospheres and the need to broaden our search for habitable worlds beyond the presence of oxygen.