Arthur J. Villasanta – Fourth Estate Contributor
Seattle, WA, United States (4E) – Stunning new research shows the Great Dying or the Permian-Triassic Extinction Event — the largest extinction in Earth’s history — in the oceans was caused by global warming that left animals unable to breathe.
This catastrophic event some 252 million years ago annihilated some 96 percent of marine species worldwide. It was followed by millions of years when life had to multiply and diversify once more.
Scientists have long debated exactly what made the oceans inhospitable to life. Among the reasons put forth are the high acidity of ocean water; a complete lack of oxygen; metal and sulfide poisoning and warmer temperatures.
New research from the University of Washington and Stanford University show that the Permian mass extinction in the oceans was caused by global warming that asphyxiated marine life. Researchers combined models of ocean conditions and animal metabolism with published lab data and paleoceanographic records to come to this conclusion.
Research shows that as temperatures rose and the metabolism of marine animals sped-up, the warmer waters could not hold enough oxygen for them to survive. This finding is eerily similar to the global ocean warming occurring today.
“This is the first time that we have made a mechanistic prediction about what caused the extinction that can be directly tested with the fossil record, which then allows us to make predictions about the causes of extinction in the future,” said first author Justin Penn, a UW doctoral student in oceanography.
The study has been published in the academic journal, Science.
Researchers ran a climate model with Earth’s configuration during the Permian, when the land masses were combined in the supercontinent called Pangaea. Oceans had temperatures and oxygen levels similar to today’s before ongoing volcanic eruptions in Siberia created a greenhouse-gas planet,
Researchers then raised greenhouse gases in the model to the level required to make tropical ocean temperatures at the surface some 10 degrees Celsius higher, matching conditions at that time.
As a result, oceans lost about 80 percent of their oxygen. About half the oceans’ seafloor, mostly at deeper depths, became completely oxygen-free.
The fossil record confirms species far from the Equator suffered most during the event.
“The signature of that kill mechanism, climate warming and oxygen loss, is this geographic pattern that’s predicted by the model and then discovered in the fossils,” said Penn. “The agreement between the two indicates this mechanism of climate warming and oxygen loss was a primary cause of the extinction.”
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