A study published in the journal Nature Geoscience in March details the lifespan of the Earth’s biosphere and how long it will take before the planet becomes uninhabitable.
Christopher Reinhard, associate professor at the Georgia Institute of Technology, and Kazumi Ozaki, assistant professor at the University of Toho, used a model that represents the climate and biochemical processes of the Earth. With this model, the researchers took into account the uncertainties in the Earth’s atmosphere and tested it more than 400,000 times, each test adjusts the parameters of the model.
According to the results of the model’s tests, the researchers found that oxygen levels will be completely depleted in about a billion years, which will prevent Earth from sustaining a life that depends on oxygen for survival. About 2.5 billion years ago, the great oxidation event occurred, spawning new life forms as the atmosphere began to fill with oxygen. Until this time, Earth was only able to support life that did not need oxygen to survive, such as anaerobic life forms.
Ozaki said: “For many years, the lifespan of the terrestrial biosphere has been discussed on the basis of scientific knowledge about the constant brightening of the sun and the global geochemical cycle of carbonate-silicate. One of the corollaries of such a theoretical framework is the continuing decline in atmospheric CO2 levels and global warming on geological time scales.“
Add, “Indeed, it is widely believed that the Earth’s biosphere will end in the next 2 billion years due to the combination of overheating and the scarcity of CO2 for photosynthesis. If this is true, then atmospheric O2 levels can be expected to decline in the distant future as well. However, it’s unclear exactly when and how this will happen.“
“The atmosphere after the great deoxygenation is characterized by high levels of methane, low levels of CO2 and no ozone layer. The Earth system is likely to be a world of anaerobic life forms.“
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