The results of a study on the duration of the oxygenated atmosphere of our planet indicate this: “The decline will be very extreme, about a million times less oxygen than there is today”.
In the future, our atmosphere will once again be rich in methane and poor in oxygen. When this change comes, probably a few billion years from now, it will all happen fairly quickly, returning our planet to something similar to the Great Oxygenation Event of about 2.4 billion years ago. This was stated by a research team from Toho University in Funabashi, Japan, which believes that atmospheric oxygen is unlikely to be a permanent feature of habitable worlds in general.
According to the researchers’ calculations, the habitable history of the oxygen-rich planet could represent only 20-30 percent of the lifespan of the Earth as a whole. “The model predicts that a deoxygenation of the atmosphere, with atmospheric O2 dropping abruptly to levels reminiscent of the Earth Archea, will most likely be triggered before the onset of wet greenhouse conditions in the Earth’s climate system and before the vast loss of surface water from the atmosphere”The researchers write in their article published in Nature Geoscience. At that point it will be the end for humans and most other life-forms that rely on oxygen, while microbial life will likely continue to exist for a long time to come.
To reach these conclusions, the researchers performed detailed models of the Earth’s biosphere, taking into account the changes in the Sun’s brightness and the corresponding drop in carbon dioxide levels, as the gas is broken down by rising heat levels. Less carbon dioxide means fewer photosynthesizing organisms such as plants, which would result in less oxygen within the next billion years.
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Scientists previously predicted that increased solar radiation would wipe out ocean waters from Earth within about two billion years, but the new model – based on an average of just under 400,000 simulations – claims that oxygen depletion it will kill life first. “The oxygen drop is very, very extreme – said a New Scientist earlier this year, Earth scientist Chris Reinhard, of the Georgia Institute of Technology. We are talking about approx a million times less oxygen than there is today”.
What makes the study relevant are its implications for finding habitable planets outside the Solar System. “Our data underscores the need for robust atmospheric bio-signatures, beyond oxygen, applicable to atmospheres of weakly oxygenated and anoxic exoplanets”The scholars observe, highlighting the potential of atmospheric organic haze during the terminal phases of planetary habitability. “After a deoxygenation event, the atmosphere is characterized by a high level of methane, low levels of CO2 and no ozone layer – the researchers indicate -. When that happens, the Earth system will likely be a world for anaerobic life forms ”.