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Laughing gas may have helped warm early Earth and given breath to life by Staff Writers Atlanta GA (SPX) Aug 24, 2018
More than an eon ago, the sun shone dimmer than it does today, but the Earth stayed warm due to a strong greenhouse gas effect, geoscience theory holds. Astronomer Carl Sagan coined this "the Faint Young Sun Paradox," and for decades, researchers have searched for the right balance of atmospheric gases that could have kept early Earth cozy. A new study led by the Georgia Institute of Technology suggests that nitrous oxide, known for its use as the dental sedative laughing gas, may have played a significant role. The research team carried out experiments and atmospheric computer modeling that in detail substantiated an existing hypothesis about the presence of nitrous oxide (N2O), a powerful greenhouse gas, in the ancient atmosphere. Established research has already pointed to high levels of carbon dioxide and methane, but they may not have been plentiful enough to sufficiently keep the globe warm without the help of N2O. Jennifer Glass, an assistant professor at Georgia Tech, and Chloe Stanton, formerly an undergraduate research assistant in the Glass lab at Georgia Tech, published the study in the journal Geobiology the week of August 20, 2018. Their work was funded by the NASA Astrobiology Institute. Stanton is now a graduate research assistant at the Pennsylvania State University.
No 'boring billion' "People in our field often refer to this middle chapter in Earth's history roughly 1.8 to 0.8 billion years ago as the 'boring billion' because we classically think of it as a very stable period," said Stanton, the study's first author. "But there were many important processes affecting ocean and atmospheric chemistry during this time." Chemistry in mid-Proterozoic ocean was heavily influenced by abundant soluble ferrous iron (Fe2+) in oxygen-free deep waters.
Ancient iron key In lab experiments, Stanton found that Fe2+ in seawater reacts rapidly with nitrogen molecules, especially nitric oxide, to yield nitrous oxide in a process called chemodenitrification. This nitrous oxide (N2O) can then bubble up into the atmosphere. When Stanton plugged the higher fluxes of nitrous oxide into the atmospheric model, the results showed that nitrous oxide could have reached ten times today's levels if mid-Proterozoic oxygen concentrations were 10 percent of those today. This higher nitrous oxide would have provided an extra boost of global warming under the Faint Young Sun.
Breathing laughing gas The Georgia Tech model provides a plentiful source of nitrous oxide in ancient iron-rich seas for this evolutionary scenario. And prior to the Proterozoic, when oxygen was extremely low, early aquatic microbes could have already been breathing nitrous oxide. "It's quite possible that life was breathing laughing gas long before it began breathing oxygen," Glass said. "Chemodenitrification might have supplied microbes with a steady source of it."
Earth's earliest animals were strange sea creatures millions of centuries ago Washington (UPI) Aug 21, 2018 New fossil analysis suggests the planet's earliest known animals emerged at least 571 million years ago. The new study - published this month in the journal Paleontology - proves members of the Ediacaran biota are indeed animals and were diversifying for several million years before the acceleration of speciation known as the Cambrian explosion. Scientists recovered the first Stromatoveris psygmoglena fossil in the mid-20th century. The frond-like sea creature baffled paleontologists f ... read more
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