“The Great Dying” happened Fast. But Not as Fast as We’re Doing it Now.
November 28, 2011
The end-Permian extinction occurred 252.2 million years ago, decimating 90 percent of marine and terrestrial species, from snails and small crustaceans to early forms of lizards and amphibians. “The Great Dying,” as it’s now known, was the most severe mass extinction in Earth’s history, and is probably the closest life has come to being completely extinguished. Possible causes include immense volcanic eruptions, rapid depletion of oxygen in the oceans, and — an unlikely option — an asteroid collision.
While the causes of this global catastrophe are unknown, an MIT-led team of researchers has now established that the end-Permian extinction was extremely rapid, triggering massive die-outs both in the oceans and on land in less than 20,000 years — the blink of an eye in geologic time. The researchers also found that this time period coincides with a massive buildup of atmospheric carbon dioxide, which likely triggered the simultaneous collapse of species in the oceans and on land.
With further calculations, the group found that the average rate at which carbon dioxide entered the atmosphere during the end-Permian extinction was slightly below today’s rate of carbon dioxide release into the atmosphere due to fossil fuel emissions. Over tens of thousands of years, increases in atmospheric carbon dioxide during the Permian period likely triggered severe global warming, accelerating species extinctions.
The researchers also discovered evidence of simultaneous and widespread wildfires that may have added to end-Permian global warming, triggering what they deem “catastrophic” soil erosion and making environments extremely arid and inhospitable.
In geologic terms, it was surprisingly quick, and it may provide a scary lesson about climate change for our future, authors of the new study say. It was the third of five extinctions in world history, occurring even before dinosaurs roamed.
This extinction killed off more than three-quarters of life on the planet in an event scientists have called the Great Dying. The Chinese dig sites provide new dates and details of the event, which occurred at the end of the Permian Era. It happened 252 million years ago and may have lasted less than 100,000 years, far shorter than scientists had thought, according to the study published Thursday in the journal Science.
The study also bolsters the prevailing scientific concept that the giant die-off was caused by a massive shift in climate – global warming, prehistoric style – triggered by volcanic activity that is far beyond modern levels. The research also makes the case that the burst of carbon dioxide and methane thrown into the atmosphere that triggered the die-off took only about 20,000 years, less than previously thought, though the ecological damage lasted longer.
And devastating fires raged worldwide, not just where the volcanoes exploded, the paper said.
“Imagine drying out the Amazon and burning it up,” said study co-author Douglas Erwin, a paleobiology curator at the Smithsonian Institution. “It certainly was a very uncomfortable time. You’re killing off 75 to 90 percent of everything on the planet. It’s not going to be terribly pleasant.”
The air at times could be like the thick smog outside an old Eastern European power plant, Erwin said.
It was the only mass extinction in history to kill off hardy insects, Erwin said. Afterward, there were very few species left worldwide, and they had little diversity among different regions. It was only later that dinosaurs and mammals roamed the Earth.
This climate change “happened naturally, and it killed everything,” Erwin said. But he said that if critics of global warming science think it shows that climate change is nothing to worry about because it has happened naturally in the past, that’s the wrong conclusion.
“I think the lesson you take away from this is that you don’t want to get anywhere close to a mass extinction,” Erwin said. “It took 5 million years before life got better again.”
Philly.com picked up the story this morning, and expanded:
It’s not the heat itself but the resulting reordering of the living world that would cause a massive die-off, said Pennsylvania State University geoscience professor Lee Kump. Natural selection proceeds. Life extinguishes other life.
According to a theory that Kump proposed several years ago to explain the Mother of all Extinctions, excess heat hinders oxygen from dissolving into the oceans. Oxygen-starved oceans become hostile to fish, plankton, and other familiar life, but friendly to sulfur-using bacteria. They poison other species by exhaling hydrogen sulfide.
Peter Ward, a professor of biology and earth and space sciences at the University of Washington, popularized Kump’s theory in his 2007 book Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future.
In his vivid visualization: “Most of the shoreline is encrusted with rotting organic matter. Silklike swaths of bacterial slick now putrefying under the blazing sun, while in the nearby shallows mounds of similar mats can be seen growing up toward the sea’s surface. . . . From shore to the horizon, there is but an unending purple color – a vast, flat, oily purple, not looking at all like water . . . no fish break its surface, no birds of any kind . . . we are under a pale green sky and it has the smell of death and poison.”
Is this our future? Kump says there’s no way to know, but the rise in carbon dioxide that triggered the end-Permian is comparable to modern projections if we do nothing to curtail use of fossil fuels worldwide over the next century or so.