While life seems to be flourishing on this oxygen-rich planet for now, scientists predict that the atmosphere will return to a rich source of methane and low levels of oxygen in the future.
This is unlikely to happen in the next billion years. However, when it does, it will happen very quickly, as the study earlier this year indicates.
This shift will return the planet to the condition it was before the Great Oxidation Event (GOE), which occurred around 2.4 billion year ago.
The researchers behind the study also believe that atmospheric oxygen will not be a permanent feature on habitable worlds. This has implications for our efforts in finding signs of life elsewhere in the Universe.
The researchers wrote in a published paper that the model projected that an atmosphere deoxygenation, with atmospheric O2 dropping sharply, to levels reminiscent the Archaean Earth. This will most likely be triggered prior to the inception of moist climate conditions in Earth's Climate System and before the substantial loss of surface water.
It will be the end for humans and all other life forms that depend on oxygen. Let's hope that we can figure out a way to leave the planet in the next billion years.
The researchers created detailed models of Earth’s biosphere to reach their conclusions. They considered changes in the brightness and carbon dioxide levels as well as heat levels. A lower level of carbon dioxide would mean fewer plants and other photosynthesizing organisms, which would lead to less oxygen.
Scientists had previously predicted that increasing radiation from the Sun would wipe the oceans off our planet in about 2 billion years. However, the new model, which is based on just under 400,000 simulations, says that the decrease in oxygen will kill all life.
"The drop is very, very severe," Chris Reinhard, an Earth scientist from the Georgia Institute of Technology told New Scientist earlier in the year. "We are talking about a million times more oxygen than what is currently available."
The study's relevance to today is due to our ongoing search for habitable planets beyond the Solar System.
Scientists want to be able find the right information in the data being collected by these powerful telescopes.
Researchers believe that it is possible that we must be searching for other biosignatures than oxygen in order to have the best chance at finding life. The NASA NExSS (Nexus For Exoplanet Science) project is examining the habitability and potential hazards of other planets.
Reinhard and Kazumi Ozaki (environmental scientist at Toho University, Japan) calculated that Earth's oxygen-rich habitable history could last for only 20-30% of its entire lifespan. Microbial life will continue to exist long after our departure.
Ozaki stated that the atmosphere following the great deoxygenation will be characterized by high levels of methane and low-levels CO2 but no ozone layer. "The Earth system will likely be populated by anaerobic life forms."
Nature Geoscience published the research.
This article was published for the first time in March 2021.