Oxygen is the key to life on Earth. But studies show that oxygen levels on Earth are dropping dramatically. Chances are, Earth will again be rich in methane and low in oxygen.
This shift will bring the planet back to the state it was in before what is known as the Great Oxidation Event (GOE) or the extraordinary oxidation event that occurred about 2.4 billion years ago.
What's more, the researchers behind the new study say that oxygen in the atmosphere will most likely no longer be a permanent feature to make Earth a habitable world forever.
The model projects that atmospheric deoxygenation, with atmospheric O2 dropping sharply, will most likely be triggered before the onset of greenhouse conditions and before the extensive loss of surface water from the atmosphere.
To arrive at that conclusion, the researchers ran detailed models of Earth's biosphere taking into account changes in the Sun's brightness and corresponding decreases in carbon dioxide levels -- as the gas is broken down as heat levels increase. Less carbon dioxide means fewer photosynthetic organisms like plants, which will produce less oxygen.
Scientists had previously estimated that increased radiation from the Sun would remove seawater from the face of our planet in about 2 billion years, but the new model says depletion of oxygen will first become a threat to life.
"The drop in oxygen is very, very extreme," Earth scientist Chris Reinhard, of the Georgia Institute of Technology, told New Scientist earlier this year.
With this discovery, there is hope that humans can look for something new besides oxygen to live life, the researchers said. Their study is part of NASA's NExSS (Nexus for Exoplanet System Science) project, which investigates the habitability of planets.
According to calculations carried out by Reinhard and environmental scientist Kazumi Ozaki, of Toho University in Japan, Earth's oxygen-rich habitable history could end within 20-30% of the planet's overall lifespan.
"The atmosphere after severe deoxygenation is characterized by increased methane, low CO2 levels, and no ozone layer. The Earth system will probably become a world with anaerobic life forms," said Ozaki. This research has been published in Nature Geoscience as extracted from Science Alert, Saturday (16/10/2021).
