As CO2 continues to increase, a NASA study has estimated the point at which Earth will run out of oxygen.
According to the research published in Nature Geoscience, Earth’s oxygen-rich atmosphere will eventually shift to a methane-rich one, wiping out life as we know it.
NASA scientists have linked the reason for this to the Sun's increasing brightness, the deceleration of the carbonate-silicate cycle, and changes in atmospheric carbon dioxide levels.
While some controversial experiments are attempting to dim the Sun and combat the effects of climate change, the US space agency assures us that Earth being deprived of oxygen is still a long way off.
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Kazumi Ozaki, Assistant Professor at Toho University and Christopher Reinhard, Associate Professor at Georgia Institute of Technology, created a model of Earth on a computer to simulate climate and biochemical processes.
From their findings, they claimed that in one billion years, Earth's oxygen could plummet to less than 10% of its current concentration.
"It's generally thought Earth's biosphere will come to an end in 2 billion years due to the combination of overheating and CO2 scarcity for photosynthesis," said Ozaki. "If true, one can expect atmospheric O2 levels will also eventually decrease in the distant future. However, it remains unclear exactly when and how this will occur."
The study, partially funded by NASA's Astrobiology program, explains that as the Sun gets hotter over time, it can trigger solar flares, which release intense energy and can significantly disrupt our planet's atmosphere and magnetosphere. As a result, our oxygen and ozone concentrations are affected.
"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 Ozaki and Reinhard in the study.
"We find that future deoxygenation is an inevitable consequence of increasing solar fluxes, whereas its precise timing is modulated by the exchange flux of reducing power between the mantle and the ocean–atmosphere–crust system."
Given that atmospheric oxygen is a biosignature for life on Earth, the study used a complex model that merges biogeochemistry and climate data to predict how the atmosphere will change.
Furthermore, scientists have long studied atmospheric oxygen as a potential sign of life on distant planets in our solar system.
By studying how Earth’s atmosphere became oxygen-rich and how those levels change over time, astrobiologists can gain insights into using oxygen as a biosignature to detect life elsewhere.