Methane didn’t warm ancient Earth, new simulations suggest | Science News

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Methane didn’t warm ancient Earth, new simulations suggest

Alternative explanation needed for why planet didn’t freeze despite dim sun

By
3:00pm, September 26, 2016
illustration of ancient earth

DIM SUN  Scarce oxygen and abundant sulfate prevented methane concentrations from getting high enough to explain why Earth didn’t freeze over around 1.8 billion to 800 million years ago when the sun was dimmer, researchers say.

Methane wasn’t the cozy blanket that kept Earth warm hundreds of millions of years ago when the sun was dim, new research suggests.

By simulating the ancient environment, researchers found that abundant sulfate and scant oxygen created conditions that kept down levels of methane — a potent greenhouse gas — around 1.8 billion to 800 million years ago (SN: 11/14/15, p. 18). So something other than methane kept Earth from becoming a snowball during this dim phase in the sun’s life. Researchers report on this new wrinkle in the so-called faint young sun paradox (SN: 5/4/13, p. 30) the week of September 26 in the Proceedings of the National Academy of Sciences.

Limited oxygen increases the production of

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