Research from the University of Maryland, the University of St. Andrews, NASA’s Jet Propulsion Laboratory, the University of Leeds, and the Blue Marble Space Science Institute (USA) suggests that more than 2.4 billion years ago, Earth’s atmosphere was inhospitable, filled with toxic gases that caused fluctuating surface temperatures. With this toxic mixture full of methane, our atmosphere passed up to a million years and would be one of the causes of activation of the Great Oxidation that occurred 2.4 billion years ago, when oxygen concentrations in the Earth’s atmosphere increased by more than 10,000. times.
Discovering the history of the Earth
The toxic haze expelled a large amount of hydrogen from the atmosphere, clearing the way for massive amounts of oxygen to fill the air. This transformation resulted in an atmosphere very similar to the one that sustains life on Earth today, as oxygen would pave the way for the emergence of more complex microorganisms such as eukaryotes and, later, complex animal life.
“The transformation of Earth’s air from a toxic mixture to a more welcoming, oxygen-rich atmosphere happened in an instant on the geological scale. With this study, we finally have the first complete picture of how the methane haze made this happen. “, clarifies James Farquhar, co-author of the work.
The researchers used detailed chemical recordings and sophisticated atmospheric models to reconstruct the chemical composition of the atmosphere during the period immediately preceding the Great Oxidation Event. Their results suggest that bacteria – the only life on Earth at the time – produced massive amounts of methane that reacted to fill the air with a thick haze, similar to the current atmosphere of Saturn’s moon Titan.
“High levels of methane meant that much more hydrogen, the main gas that prevents oxygen build-up, was able to escape into outer space, paving the way for global oxygenation. Our new dataset constitutes the highest resolution record in chemistry. archaic atmospheric atmosphere ever produced , and it paints a dramatic picture of the conditions of the Earth’s surface before the oxygenation of our planet “, comments Aubrey Zerkle, co-author of the work.
Thus, this methane haze persisted for about a million years ; After enough hydrogen had escaped from the atmosphere, the right chemical conditions took over and the oxygen boom kicked in, allowing all multicellular life to evolve.
The article has been published in the journal Proceedings of the National Academy of Sciences (PNAS).
