Earth Has Survived Extinctions Before, IT'S HUMANS WHO ARE FRAGILE
- Opinion: Earth Has Survived Extinctions Before, It's Humans Who Are Fragile- *RADIO NPR, Scott Simon, Sept. 7, 2019.
It takes only a few paragraphs in Genesis for the Earth to take shape, sprout with life, and then human beings. Of course, that development actually took millions of years. But this week, as the world watched a huge hurricane gather in the Earth's warming waters, and wreak terrible destruction on life in the islands of the Bahamas and other places, there was another humbling reminder that human beings really only play a supporting role in the history of the Earth.
Scientists have uncovered what they call the Great Oxidation Event. They say it destroyed almost all life on Earth about 2 billion years ago, even before the rise and extinction of the dinosaurs, a mere millions of years ago..Scientists say the Earth's only living inhabitants about 2 billion years ago were microorganisms. But when they photosynthesized, that process that turns light into chemical energy, the tiny organisms saturated the Earth with oxygen — too much oxygen. The excess essentially poisoned the atmosphere for 80 to 99.5% of the organisms that then thrived on Earth; and left the planet almost lifeless.
Malcolm Hodgskiss told CNN, "Even our most conservative estimates would exceed estimates for the amount of life that died off during the extinction of the dinosaurs approximately 65 million years ago." ..A new scientific study and actual events reminded us this week that the Earth endures. It's us, all the living things that inhabit it for a while, who are fragile; and who know our time is fleeting...
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https://www.npr.org/2019/09/07/758448991/opinion-earth-has-survived-extinctions-before-its-humans-who-are-fragile
- A gas flare from the Shell Chemical LP petroleum refinery illuminates the sky on Aug. 21 in Norco, La.
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There was virtually no oxygen; as it was produced by photosynthesis, it dragged iron out of the oceans and produced the banded iron formations that provided the means for the industrial revolution and modern steel manufacturing.
Since the O2 was produced in the water, you see the problem in trying to make any kind of guesses as to what the actual atmosphere and circulation patterns of the dissolved or gaseous oxygen were.
The Earth's atmosphere was reducing way back then. Think modern-day anaerobic bacteria. Many species die upon exposure to oxygen, which is toxic to them. Now make that true for almost all species on Earth.
Granted, this was a couple billion (not "a few millions"
of years ago, long before the Cambrian explosion and its precursors. All life was pretty much microscopic or lumps of microscopic things that weren't well differentiated as to their roles. Perhaps some symbiosis, but if we got up to little lumpy squishy things that could locomote by then it would be surprising.
I heard the sermonette this morning while on the road. (And that's what it struck me as. Preaching.) My first annoyance was that the radio host seemed to think this was some new discovery of an extinction event, as opposed to just quantifying one that was well known and placing the level of extinction higher than the mostly hypothetical guesses available when I taught this stuff in a high school science class years ago.
