How Long Will Oxygen-Rich Atmosphere Sustain On Earth? Study Says...

Oxygen, the invisible elixir of life, is omnipresent on Earth, shaping the very essence of our existence. This life-sustaining gas, constituting about 21 per cent of the Earth's atmosphere, plays a pivotal role in the survival of countless species. But this was not always the case. When the planet was formed around 4.5 billion years ago, the conditions were vastly different. Carbon dioxide, methane and water vapour were dominant in Earth's atmosphere. And scientists have predicted that in future, Earth's atmosphere will revert to one that's low in oxygen.

A study, published in Nature in 2021, describes the scenario when it will happen. That time is still a billion years away, but when the change come, it is going to happen fairly rapidly.

The shift will take Earth back to something like the state it was in before what's known as the Great Oxidation Event (GOE) around 2.4 billion years ago, said the study.

The research is again in news as scientists are searching for habitable planets outside the Solar System. It say that atmospheric oxygen is unlikely to be a permanent feature of habitable worlds in general.

"The drop in oxygen is very, very extreme. We're talking around a million times less oxygen than there is today," Chris Reinhard, from the Georgia Institute of Technology, told New Scientist.

Scientists who predicted the doomsday scenario have said in the research, "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."

Researchers created detailed models of Earth's atmosphere, analysing changes in the brightness of the Sun and the corresponding drop in carbon dioxide levels. Less carbon dioxide means fewer photosynthesizing organisms such as plants, which would result in less oxygen.