Enjoy It While You Can: Rapidly Dropping Oxygen Will Eventually Suffocate Most Life on Earth

Currently, life is thriving on our oxygen-rich planet, but this was not always the case, and scientists believe that the atmosphere will return to one that is high in methane and low in oxygen in the future.

This is unlikely to occur during the next billion or so years. However, research from earlier this year indicates that when the transition occurs, it will occur rapidly.

Prior to the Great Oxidation Event (GOE) around 2.4 billion years ago, this change will restore the world to a comparable condition.

In addition, the authors of the current research estimate that atmospheric oxygen is unlikely to be a persistent characteristic of habitable planets in general, which has consequences for our attempts to uncover signs of life in the cosmos.

“The model projects that a deoxygenation of the atmosphere, with atmospheric O2 dropping sharply to levels reminiscent of the Archaean Earth, will most probably be triggered before the inception of moist greenhouse conditions in Earth’s climate system and before the extensive loss of surface water from the atmosphere,” wrote the researchers in their published paper.

At that time, humans and most other life forms dependent on oxygen would perish, so let's hope we can find out a way to escape the planet within the next billion years.

To reach these results, the researchers conducted extensive simulations of the Earth's biosphere, taking into consideration changes in the Sun's luminosity and the associated decrease in carbon dioxide levels as the gas is broken down by rising temperatures. Less carbon dioxide results in fewer photosynthesizing organisms, such as plants, and therefore less oxygen.

Based on an average of slightly under 400,000 simulations, the new model predicts that a decline in oxygen would wipe out life before increasing solar radiation.

“The drop in oxygen is very, very extreme,” Earth scientist Chris Reinhard, from the Georgia Institute of Technology, told New Scientist earlier this year. “We’re talking around a million times less oxygen than there is today.”

Due to our hunt for habitable planets outside the Solar System, the research is particularly pertinent today.

According to experts, we may need to search for biosignatures other than oxygen if we are to have the greatest chance of discovering life. Their research is part of the NASA NExSS (Nexus for Exoplanet System Science) program, which investigates the habitability of extraterrestrial planets.

According to calculations performed by Reinhard and environmental scientist Kazumi Ozaki of Japan's Toho University, Earth's oxygen-rich habitable history may end up lasting only 20 to 30 percent of the planet's total lifespan; however, microbial life will continue to exist long after we are extinct.

“The atmosphere after the great deoxygenation is characterised by an elevated methane, low-levels of CO2, and no ozone layer,” said Ozaki. “The Earth system will probably be a world of anaerobic life forms.”

Reference(s): Peer-Reviewed Research, NewScientist

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