For now, life is flourishing on our oxygen-rich planet, but the Earth was not always like that, and scientists have predicted that in the future the atmosphere will be rich in methane and low in oxygen.
This probably won’t happen for more than a billion years or so. But when the change comes, it will happen pretty quickly, the study suggests.
This change will cause the planet to return to something like the state it was in before what is known as the Great Oxidation Event (GOE) about 2.4 billion years ago.
In addition, the researchers behind the new study say that atmospheric oxygen is unlikely to be a permanent feature of habitable worlds in general, which has implications for our efforts to detect signs of life beyond the Universe.
“The model projects that a deoxygenation of the atmosphere, with atmospheric O2 that will drop sharply to levels reminiscent of the Archaeological Earth, will likely be triggered before the onset of humid greenhouse conditions in the Earth’s climate system and before of the extensive loss of surface water from the atmosphere, ”the researchers write in their published article.
Right now it will be the end of the road for humans and for most other oxygen-dependent life forms to spend the day, so we hope to find out how to get off the planet sometime in the next billion. of years.
To reach their conclusions, the researchers conducted detailed models of the Earth’s biosphere, taking into account changes in the Sun’s brightness and the corresponding drop in carbon dioxide levels, as the gas decomposes as levels increase. of heat. Less carbon dioxide means fewer photosynthesizing organisms like plants, which would result in less oxygen.
Scientists have previously predicted that rising solar radiation would clear the ocean waters of our planet’s surface in about 2 billion years, but the new model, based on an average of just under 400,000 simulations , says reducing oxygen will kill you out of life first.
“Oxygen drop is very, very extreme,” said Earth scientist Chris Reinhard of the Georgia Institute of Technology New scientist. “We’re talking about a million times less oxygen than there is today.”
What makes the study especially relevant to our day is our search for habitable planets outside the solar system.
Increasingly powerful telescopes are coming online and scientists want to know what they should look for in the data scales that these instruments are collecting.
Researchers say we may need to look for other biosignatures, apart from oxygen, to have the best chance of detecting life. His study is part of NASA’s NExSS project (Nexus for Exoplanet System Science), which investigates the habitability of planets other than ours.
According to calculations by Reinhard and environmental scientist Kazumi Ozaki of Toho University in Japan, the Earth’s oxygen-rich habitable history could end up lasting only 20-30 percent of the planet’s life in general, and microbial life will last in existence long after our demise.
“The atmosphere after the great deoxygenation is characterized by high methane, low CO2 levels and no ozone layer,” says Ozaki. “The terrestrial system will probably be a world of anaerobic life forms.”
The research has been published in Geoscience of nature.