Produced by: Tarun Mishra Designed by: Manoj Kumar
Scientists have projected a significant atmospheric transformation, resembling conditions before the Great Oxidation Event (GOE) 2.4 billion years ago, which ushered in the era of oxygen-rich environments crucial for aerobic life.
Recent 2021 research indicated a potential looming deoxygenation event within the next billion years, leading to an atmosphere dominated by methane, reminiscent of the Archaean Earth, posing a threat to oxygen-dependent life forms.
The study suggested a rapid decline in oxygen levels, estimated to be a million times less than current levels, potentially rendering the planet inhospitable to aerobic organisms, including humans, unless alternative solutions are developed.
Scientists utilised complex models considering the Sun's increasing luminosity and declining carbon dioxide levels. As heat broke down CO2, photosynthetic organisms like plants diminished, causing a drastic reduction in oxygen production.
Contrary to previous predictions of evaporating oceans in 2 billion years, the new model, based on nearly 400,000 simulations, revealed that oxygen depletion preceded the loss of surface water, proving more immediately fatal to life on Earth.
Earth scientist Chris Reinhard highlighted the severity of the predicted oxygen decline, emphasising estimates indicating levels a million times less than current, posing a grave threat to the majority of life forms thriving then.
The research had significant implications for the search for extraterrestrial life, suggesting that oxygen may not be the sole biosignature for habitable planets. Alternative biosignatures needed consideration in the quest to detect alien life.
The study was part of NASA's NExSS project, advising astronomers to consider alternative biosignatures as they utilised powerful telescopes in the search for habitable planets beyond our solar system.
In the projected scenario, Earth's atmosphere post-deoxygenation would feature elevated methane levels, low CO2, and the absence of a protective ozone layer. Anaerobic life forms would dominate, continuing the cycle of life after oxygen-dependent species vanished.
The research suggested that Earth's oxygen-rich era, critical for supporting current life forms, only lasted for 20-30 percent of the planet's total lifespan. As humanity confronts climate change, this glimpse into the distant past serves as a reminder of the planet's ever-changing nature and the transient conditions supporting life as we knew it.