According to a new numerical model of biogeochemistry and climate, developed by researchers at the Georgia Institute of Technology, the Earth will maintain its atmosphere rich in oxygen for a billion years , before rapid deoxygenation makes the atmosphere reminiscent of the early Earth.
The study, published in Nature , has important ramifications not only for the future of Earth’s biosphere, but also for the search for life on Earth-like planets.
Oxygen (and the photochemical by-product, ozone) is the most accepted biological signature for the search for life on exoplanets, and, from the looks of it, the oxygen-rich atmosphere could only be possible for 20-30% of all. the history of the Earth as an inhabited planet .
The atmosphere after the great deoxygenation is characterized by high methane, low CO2 levels and no ozone layer. The Earth system will likely be a world of anaerobic life forms.
Since the modeling of the future evolution of the Earth harbors many uncertainties in geological and biological evolutions, for modeling the future evolution of the Earth it adopted a stochastic approach , which allows researchers to obtain a probabilistic assessment of life. useful of an oxygenated atmosphere.
As explained by Kazumi Ozaki , assistant professor at Toho University and lead author of the research:
For many years, the lifespan of the Earth’s biosphere has been debated based on scientific knowledge about the constant brightness of the sun and the global carbonate-silicate geochemical cycle. One of the corollaries of such a theoretical framework is a continuous decrease in atmospheric CO2 levels and global warming on geological time scales. In fact, it is generally thought that the Earth’s biosphere will come to an end in the next 2 billion years due to the combination of overheating and a shortage of CO2 for photosynthesis. If true, it can be expected that atmospheric O2 levels will also eventually decrease in the distant future. However, it is not clear exactly when and how this will occur.