Privileged Planet: short early days and oxygen levels (Introduction)

by David Turell , Tuesday, August 03, 2021, 15:22 (1208 days ago) @ David Turell

A new theory estimating early days short length and how that may have related to staggered oxygen production from cyanobacteria mats:

https://www.sciencemag.org/news/2021/08/totally-new-idea-suggests-longer-days-early-ear...

"Now a research team has proposed a novel link between how fast our planet spun on its axis, which defines the length of a day, and the ancient production of additional oxygen. Their modeling of Earth’s early days, which incorporates evidence from microbial mats coating the bottom of a shallow, sunlit sinkhole in Lake Huron, produced a surprising conclusion: as Earth’s spin slowed, the resulting longer days could have triggered more photosynthesis from similar mats, allowing oxygen to build up in ancient seas and diffuse up into the atmosphere.

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"Microbes that became cyanobacteria evolved the molecular machinery for photosynthesis early on, letting them convert carbon dioxide and water into sugars and oxygen. Researchers have long thought these microbes provided Earth’s initial supply of oxygen, over the eons creating an environment that favored the evolution of aerobic life in all its forms. But they always puzzled over why about a billion years passed between the first photosynthetic microbes, which fossils indicate arose about 3.5 billion years ago, and the first good geological evidence for a buildup of oxygen.

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"Many agree that 4.5 billion years ago, a day was only about 6 hours long. By about 2.4 billion years ago, the models predict, the pull of the Moon had slowed that spin to about a 21-hour day. Earth’s rotational speed then stayed constant for about a billion years, as its gravitational pull countered the Moon’s drag. Those forces fell out of balance about 700 million years ago, because the resonance cycle between Earth and the Moon is not completely stable, and the planet’s spin slowed to its current speed, creating a 24-hour day, according to the models.

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"...oxygen first jumped during what’s called the Great Oxygenation Event, some 2.4 billion years ago, and then again during the Neoproterozoic era, more than a billion years later. During the Paleozoic, about 400 million years ago, there was a final major increase in atmospheric oxygen.

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"Models suggest the amount of oxygen on Earth increased in a stepwise fashion, starting with the Great Oxygenation Event (GOE) about 2.4 billion years ago, followed by a plateau for a "boring billion" years. Oxygen rose again in the Neoproterozoic Oxygenation Event (NOE) and Palaeozoic Oxidation Event (POE). Day length rose in the same stepped pattern, suggesting that the added light boosted photosynthetic microbes, fueling increases in oxygen.

"This “elegant” idea helps explain why oxygen didn’t build up in the atmosphere as soon as cyanobacteria appeared on the scene 3.5 billion years ago, says Timothy Lyons, a biogeochemist at the University of California, Riverside. Because day length was still so short back then, oxygen in the mats never had a chance to build up enough to diffuse out. “Long daytimes simply allow more oxygen to escape to the overlying waters and eventually the atmosphere,” Lyons says.

"Still, Lyons and others say, many factors likely contributed to the rise in oxygen. For example, Fischer suspects free-floating cyanobacteria, not just those in rock-affixed mats, were big players. Benjamin Mills, an Earth system modeler at the University of Leeds, thinks the release of oxygen-binding minerals by ancient volcanoes likely countered the early buildup of the gas at times and should be factored into oxygen calculations."

Comment: The Earth evolved to its present state over time. The universe evolved to its present state after the BB. Life evolved from simple Archaea. Our reality has appeared to reach its present state by processes of evolution. If God is in charge He uses evolution to reach His goals.