Oxygen is a chemical element that is essential to life, helping some living organisms breathe, fuel our cells, and support our bodies in their physiological processes. The element is also attributed for the proliferation of life and growth of our life from microorganisms, especially since the phenomenon around 2.4 to 2.1 billion years ago called the Great Oxidation Event (GOE).
Also called as the Great Oxygenation Event or the Oxygen Catastrophe, GOE is a phenomenon that allowed the gradual accumulation of oxygen on Earth's atmosphere and oceans. Existing scientific evidence have shown that the historic event occurred when cyanobacteria living in our waters started emitting oxygen through photosynthesis, replacing the chemical compound methane in the atmosphere.
Now, a study shows that Earth will pass through a deoxygenation event or decrease in oxygen in the future, where the amount of oxygen is low with methane being dominant. Scientists predict the dropping of oxygen will suffocate most life on Earth, including humans, animals, and plants. The prediction is based on models which show atmospheric oxygen will drop to levels similar to an Archaean Earth.
Future Deoxygenation
In the study published in the journal Nature Geoscience in March 2021, researchers from the United States and Japan laid out the notion that the future lifespan of Earth's oxygenated atmosphere is uncertain. In addition, they acknowledged the Blue Planet's modern atmosphere is highly oxygenated but indicated oxygen's presence in the surface biosphere is finite.
The study implies that the deoxygenation event will not happen at least in the next billion years, but when it does the depletion of oxygen will occur rapidly. Furthermore, the research team found that atmospheric oxygen is unlikely to be a permanent aspect of habitable worlds in general. This theory may have implications for our struggle to detect signs of life in the Universe, as expounded by Science Alert.
Also Read: Life on Earth Older than Previous Estimates; Traces of Oxygen Found in 3 Billion-year-old Rocks
Stochastic Approach
The authors behind the 2021 paper used a combination of biogeochemistry and climate model to determine the probable timescale of oxygen-rich atmospheric conditions on our planet. Using a method called stochastic approach, the team found that the mean future lifespan of Earth's atmosphere is between 1.08 and 0.14 billion years, with only 1% oxygen levels of our current atmosphere.
The model projects that guided the researchers show that the deoxygenation of the atmosphere will most likely be triggered before the onset of moist greenhouse conditions on the climate and before the loss of surface water from the atmosphere.
The Great Oxidation Event
In reference to GOE, scientists studying the early Earth or prior to the oxygenation event posed a theory that the consumption of oxygen was perhaps faster than the production of oxygen through photosynthesis, according to a study from the Arizona State University.
While the Arizona university study determined that weathering rocks may have also contributed to GOE, it is unclear if a similar event in the future will occur again to alter a planet where oxygen levels are low.
Related Article: Oxygenation on Earth Likely Originated from Microbes and Minerals