Early Earth had a hazy, methane-filled atmosphere

March 13, 2017 by Matthew Wright
A new research paper describes a period more than 2.4 billion years ago, when Earth's atmosphere was filled with a thick, methane-rich haze much like Saturn's moon Titan, seen here in an image taken by NASA's Cassini spacecraft in 2013. Credit: NASA/JPL-Caltech/Space Science Institute

More than 2.4 billion years ago, Earth's atmosphere was inhospitable, filled with toxic gases that drove wildly fluctuating surface temperatures. Understanding how today's world of mild climates and breathable air took shape is a fundamental question in Earth science.

New 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 Institute of Science suggests that long ago, Earth's spent about a million years filled with a methane-rich haze. This haze drove a large amount of hydrogen out of the atmosphere, clearing the way for massive amounts of oxygen to fill the air. This transformation resulted in an atmosphere much like the one that sustains life on Earth today.

The group's results, published March 13, 2017 in the early online edition of the Proceedings of the National Academy of Sciences, propose a new contributing cause for the Great Oxidation Event, which occurred 2.4 billion years ago, when oxygen concentrations in the Earth's atmosphere increased more than 10,000 times.

"The transformation of Earth's air from a toxic mix to a more welcoming, oxygen-rich atmosphere happened in a geological instant," said James Farquhar, a professor of geology at UMD and a co-author of the study. Farquhar also has an appointment at UMD's Earth System Science Interdisciplinary Center. "With this study, we finally have the first complete picture of how methane haze made this happen."

The researchers used detailed chemical records and sophisticated atmospheric models to reconstruct atmospheric chemistry during the time period immediately before the Great Oxidation Event. Their results suggest that ancient bacteria—the only life on Earth at the time—produced massive amounts of methane that reacted to fill the air with a thick haze, resembling the modern-day atmosphere of Saturn's moon Titan.

Previous studies by many of the same researchers had identified several such haze events early in Earth's history. But the current study is the first to show how rapidly these events began and how long they lasted.

"High methane levels meant that more hydrogen, the main gas preventing the build up of oxygen, could escape into outer space, paving the way for global oxygenation," said Aubrey Zerkle, a biogeochemist at the University of St. Andrews and a co-author of the study. "Our new dataset constitutes the highest resolution record of Archean atmospheric chemistry ever produced, and paints a dramatic picture of Earth surface conditions before the oxygenation of our planet."

The methane haze persisted for about a million years. After enough hydrogen left the atmosphere, the right chemical conditions took over and the oxygen boom got underway, enabling the evolution of all multicellular life.

The key to the researchers' analysis was the discovery of anomalous patterns of sulfur isotopes in the geochemical records from this time. Sulfur isotopes are often used as a proxy to reconstruct ancient atmospheric conditions, but previous investigations into the time period in question had not revealed anything too unusual.

"Reconstructing the evolution of atmospheric chemistry has long been the focus of geochemical research," said Gareth Izon, lead author of the study, who contributed to the research while a postdoctoral researcher at St. Andrews and is now a postdoctoral researcher at the Massachusetts Institute of Technology. "Our new data show that the chemical composition of the atmosphere was dynamic and, at least in the prelude to the Great Oxidation Event, hypersensitive to biological regulation."

The research paper, "Biological regulation of en route to planetary oxygenation," Gareth Izon, Aubrey Zerkle, Kenneth Williford, James Farquar, Simon Poulton, and Mark Claire, was published March 13, 2017 in the Proceedings of the National Academy of Sciences.

Explore further: Early Earth forecast calls for periodically hazy skies

More information: Biological regulation of atmospheric chemistry en route to planetary oxygenation, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1618798114

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8 comments

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dudester
not rated yet Mar 13, 2017
So did the subsequent oxygen build-up result from symbiont species of bacteria and mitochondria or do the researchers propose some other pathway?
Osiris1
not rated yet Mar 14, 2017
That early Earth looks in the pic like Venus now. It has been said that long ago the Sun was hotter and more active in other ways. Perhaps Venus was seared then as now, and Earth was not far behind. However, Venus has no magnetic field now, and a near retrograde rotation generating its very long day. Maybe then Mars was much more habitable, and having no magnetic field to protect its atmosphere slowly lost if. Possibly it had life as well, and conditions caused it to leak life into the Solar System at a prodigious rate. Some of that life maybe came here to earth. It would have had long odds to survive, but then If you play the same game at the lottery twice daily for a million years it is logical to assume you might win.
FredJose
1 / 5 (4) Mar 14, 2017
More than 2.4 billion years ago, Earth's atmosphere was inhospitable, filled with toxic gases that drove wildly fluctuating surface temperatures

Firstly, the times given are pure thumbsuck, there's no concrete proof that it happened the way this article speculates. No observations, no way to repeat it and hence no way to verify it. It is pure non-science.
Secondly, there are strong contradictions that state that life first arose on earth 3.5 billion years ago. So how can this "date" be valid? Would life have miraculously sprung up all by itself in such a hostile environment? Or would it have perished after springing up 3.5 billion years ago and then sprung up again after the hostile environment passed?

Just the FACT that life cannot spring up all by itself from purely random naturalistic chemical and physical processes without any outside intelligent help should tell one that this story has more holes than a sieve.
FredJose
1 / 5 (4) Mar 14, 2017
@Osiris1
Possibly it had life as well,

Where and how did the life arrive or arise on Mars by purely materialistic processes? That is not possible. Has never been shown to happen and quite to the contrary we KNOW from about 6000 years of history that once something dies it cannot come back to life again all by itself.
434a
5 / 5 (3) Mar 14, 2017


Just the FACT that life cannot spring up all by itself from purely random naturalistic chemical and physical processes without any outside intelligent help should tell one that this story has more holes than a sieve.


Hi Fred, that's amazing! You know this for a FACT!! You have actual evidence of aliens seeding the Earth with life for a FACT!!! Wow!!!! I'm really excited to read your paper, is it in Nature this month? I bet it is!!!!!! You must be so proud!!!!!!

I had a look online for your paper Fred, it's not there :(
I don't understand. You said it was a FACT, with caps lock and everything.
You didn't lie did you Fred?
That would be terrible if you lied Fred, that you knew something for a FACT and you really didn't, you just made it up and said it because you were angry that people were saying stuff you didn't like. I can't believe that about you Fred, show me the evidence, please!
antialias_physorg
5 / 5 (3) Mar 14, 2017
Hi Fred, that's amazing!

I think my sarcasm-o-meter just 'sploded.
434a
5 / 5 (3) Mar 14, 2017
Hi Fred, that's amazing!

I think my sarcasm-o-meter just 'sploded.


Sarcasm? Moi? How very dare you!?
Fred knows stuff for a FACT. He'll be along in a minute with all of the evidence......in a minute......all of the evidence.....
cortezz
not rated yet Mar 14, 2017
Hey Fred, even the pope has announced that big bang and evolution are real things. And he is basicly next to god if you really believe in those things.

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