New findings challenge decades-held theories about Earth’s early atmosphere

New findings about Earth’s early atmosphere directly challenge decades-held belief about the type of atmosphere out of which life on our planet arose.

New findings about Earth’s early atmosphere directly challenge decades-held belief about the type of atmosphere out of which life on our planet arose.

Image credit: Kevin Dooley

Instead of being filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia, as scientists have believed for decades, the atmosphere of Earth just 500 million years after its creation was dominated by the more oxygen-rich compounds that are found in our current atmosphere — including water, carbon dioxide, and sulfur dioxide. That’s according to a group of scientists in the New York Center for Astrobiology at Rensselaer Polytechnic Institute, whose paper on the subject appears in the Dec. 1 edition of the journal Nature.

Bruce Watson, Institute Professor of Science at Rensselaer, thinks his group’s discoveries may reinvigorate theories that perhaps the building blocks for life were not created on Earth, but delivered from elsewhere in the galaxy.

The researchers used the oldest minerals on Earth to reconstruct the atmospheric conditions present on Earth very soon after its birth. The findings are the first direct evidence of what the ancient atmosphere of the planet was like soon after its formation and directly challenge years of research on the type of atmosphere out of which life arose on the planet.

For decades, scientists believed that oxygen was greatly limited in the atmosphere of early Earth. Such oxygen-poor conditions would have resulted in an atmosphere filled with noxious methane, carbon monoxide, hydrogen sulfide, and ammonia. To date, there remain widely held theories and studies of how life on Earth may have been built out of this deadly atmosphere cocktail.

Now, scientists at Rensselaer are turning these atmospheric assumptions on their heads with findings that prove the conditions on early Earth were simply not conducive to the formation of this type of atmosphere, but rather to an atmosphere dominated by the more oxygen-rich compounds found within our current atmosphere — including water, carbon dioxide, and sulfur dioxide. Watson said:

We can now say with some certainty that many scientists studying the origins of life on Earth simply picked the wrong atmosphere.

Bottom line: New findings, published December 1 in the journal Nature, suggest that the atmosphere of Earth just 500 million years after its creation was dominated by the oxygen-rich compounds that are found in our current atmosphere — including water, carbon dioxide, and sulfur dioxide. These findings directly challenge decades-held belief that Earth’s early atmosphere was filled with noxious methane, carbon monoxide, hydrogen sulfide.

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