The Planet Has Seen Sudden Warming Before. It Wiped Out Almost Everything.
By Carl Zimmer
Dec. 7, 2018
Some 252 million years ago, Earth almost died.
In the oceans, 96 percent of all species became extinct. It’s harder to determine how many terrestrial species vanished, but the loss was comparable.
This mass extinction, at the end of the Permian Period, was the worst in the planet’s history, and it happened over a few thousand years at most — the blink of a geological eye.
On Thursday, a team of scientists offered a detailed accounting of how marine life was wiped out during the Permian-Triassic mass extinction. Global warming robbed the oceans of oxygen, they say, putting many species under so much stress that they died off.
And we may be repeating the process, the scientists warn. If so, then climate change is “solidly in the category of a catastrophic extinction event,” said Curtis Deutsch, an earth scientist at the University of Washington and co-author of the new study, published in the journal Science.
Researchers have long known the general outlines of Permian-Triassic cataclysm. Just before the extinctions, volcanoes in what is now Siberia erupted on a tremendous scale. The magma and lava that they belched forth produced huge amounts of carbon dioxide.
Once in the atmosphere, the gas trapped heat. Researchers estimate that the surface of the ocean warmed by about 18 degrees Fahrenheit. Some researchers argue that the heat alone killed off many species.
Others believe that the warmth reduced oxygen in the ocean, asphyxiating the species living there. Rocks from the mass extinction appear to have formed when at least some of the ocean was lacking oxygen.
https://www.nytimes.com/2018/12/07/science/climate-change-mass-extinction.html?action=click&module=Top%20Stories&pgtype=Homepage
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