For now life is thriving on our oxygen-rich planet, but the Earth was not always like that – and scientists have predicted that, in the future, the feeling will return to one that is rich in methane and low in oxygen.
This may not happen for a billion years or so. But when the change comes, it’s going to happen very quickly, the study suggests.
This move will bring the planet back to something like the state it was in before the Big Oxide Event (GOE) was called around 2.4 billion years ago.
In addition, the researchers behind the new study say that air oxygen does not appear to be a permanent feature of the agricultural world at large, which affects our efforts to improve life signals. find further out in the Universe.
“The models may suggest that the atmosphere is disinfected, with atmospheric O2 dropping rapidly to levels similar to Archanean Earth, before the onset of a humid greenhouse in a conventional system. Earth’s climate and before surface water is lost from the atmosphere, “the researchers wrote in their published paper.
At that point it will be the end of the road for humans and most other life forms that rely on getting oxygen during the day, so we hope to find out how that we will get off the planet at some point within the next billion years. .
To reach their conclusions, the researchers ran detailed models of the Earth’s biosphere, including changes in the sun’s brightness and the corresponding reduction in carbon dioxide levels, as the gas is broken down by increasing heat levels. Less carbon dioxide means fewer photosynthesising organisms like plants, which would lead to less oxygen.
Scientists have previously said that more radiation from the Sun would sweep sea waters off the face of our planet within about 2 billion years, but the new model – based on an average of just under 400,000 samples – says that the reduction in oxygen is going to kill off life first.
“The drop in oxygen 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 it is today.”
What makes the study particularly relevant today is our search for arable planets outside the Solar System.
Increasingly powerful telescopes are coming online, and scientists want to be able to figure out what to look for in the data sources that these instruments contain. gathering.
It is possible that we need to hunt for other biosignatures in addition to oxygen to get the best chance of life, the researchers say. Their study is part of NASA’s NExSS (Nexus for Exoplanet System Science) project, which is exploring the potential of planets in addition to our own.
According to the calculations run by Reinhard and environmental scientist Kazumi Ozaki, from the University of Toho in Japan, the history of the Earth’s oxygen-rich arable land could last for only 20-30 percent of its life. ‘planet as a whole – and microbial life will continue to exist long after we leave.
“The atmosphere after the major deoxygenation is characterized by elevated methane, low levels of CO2, or ozone depletion,” Ozaki says. “The Earth system may be a world of anaerobic life forms.”
The research was published in Geology of nature.