Paleontologist Stephen Jay Gould once noted that ever since life began on Earth, it has remained in existence. There’s never been a point where, after life began, there were zero living things on the planet. But that doesn’t mean there haven’t been close calls. The End-Permian Extinction, which occurred around 250 million years ago, killed off 90 percent of life on the planet. A new study examines what gave this extinction, which was powered by volcanoes, its unique power.
There are many names for the End-Permian Extinction, including “the Permian–Triassic extinction event” and “the Great Dying.” The only extinction event in history which decimated insects as well as larger animals, it caused a loss of biodiversity so great that it took the global ecosystem ten million years to recover. The extinction largely stemmed from a volcanic explosion in Russia known as the Siberian Flood Basalts.
While volcanic explosions are still natural disasters, they occur today without threats of extinction. There had to something unique about the Siberian Flood Basalts.
“The scale of this extinction was so incredible that scientists have often wondered what made the Siberian Flood Basalts so much more deadly than other similar eruptions,” says Michael Broadley, a postdoc researcher at the Centre for Petrographic and Geochemical Research in Vandœuvre-lès-Nancy, France, and lead author of the paper, in a press statement.
Time was certainly a factor. The Siberian Flood Basalts exploded for nearly a million years straight. Scientist have several theories for what it was doing during this time, including that it was pumping deadly microbes into the air. This latest study examines what was lying below the Siberian Flood Basalts, rock between the crust and the mantle known as the lithosphere.
The Siberian lithosphere was loaded with chlorine, bromine, and iodine. These all chemical elements from the halogen group of the periodic table. Breathing in gas with these elements is highly toxic and usually deadly—the Center for Disease Control warns strongly against breathing any of these three elements.
The animals of the Permian–Triassic had no choice The plumes that covered the planet pounded these deadly chemicals into the atmosphere, triggering a chain of events that barely any life could survive. Broadley’s team was able to show that after the thousands of years of continual explosion, the Siberian lithosphere seemed to have exhausted itself of its deadly chemicals.
“We concluded that the large reservoir of halogens that was stored in the Siberian lithosphere was sent into the earth’s atmosphere during the volcanic explosion, effectively destroying the ozone layer at the time and contributing to the mass extinction,” Broadley says.
There are other theories about how the Great Dying racked up such astonishing numbers. Among these are extreme coal burning which would have led to a greater acidification of the ocean and triggered a form of global warming.
Its possible, of course, that these events all happened in tandem. Killing off 90 percent of marine species and 70 percent of land species isn’t the sort of thing that happens every day.
Originally posted on: Popular Mechanics USA