2014-02-20. Seeking a Break in a 252 Million-Year-Old Mass Killing. A Geologist Investigates a Mass Extinction at the End of the Permian Period.

posted Feb 25, 2014, 2:47 PM by Alan Gould

For GSS Life and Climate chapter 8. Excerpt: Sam Bowring ... a geologist at M.I.T. ... wants to understand how an estimated 96 percent of all species on Earth became extinct at the end of the Permian Period 252 million years ago...the biggest of the five mass extinctions recorded in the fossil record. ...Dr. Bowring and his colleagues have ... made the most precise measurement yet of how long it took for all those species to become extinct...less than about 60,000 years. That’s a geological blink of an eye — a fact that will help scientists evaluate different hypotheses for what triggered the mass extinction. ...Studies on the rocks that formed around the time of the mass extinction ... revealed that ...Huge volcanoes in Siberia belched molten rock that covered millions of square miles. The oceans warmed dramatically, climbing 18 degrees Fahrenheit. ...the carbon in the rocks that formed around the time of the mass extinction...have a drastically higher ratio of light-to-heavy carbon. One way to create such a planet-wide shift would be to deliver a huge surge of carbon dioxide into the ocean. ...The volcanoes may well be the cause, but scientists have yet to establish all the links from eruptions to extinctions. ...the Siberian eruptions lasted for one to two million years. But the world’s biodiversity did not decline over a similar time scale. Instead, it swiftly collapsed with little advance warning.... http://www.nytimes.com/2014/02/21/science/earth/Mass-Extinction-Permian-Period.html. Carl Zimmer, The New York Times.