Scientists link ocean acidification to prehistoric mass extinction

BY GWYNETH DICKEY New evidence gleaned by analyzing calcium embedded in Chinese limestone suggests that volcanoes, which spewed massive amounts of carbon dioxide into the atmosphere for a million years, caused the biggest mass extinction on Earth. In a paper published April 26 in the Proceedings of the National Academy of Sciences, a team of researchers led by a Stanford geologist said that as carbon dioxide gas dissolved in the oceans, it raised the acidity of seawater. The research team said it was a deadly combination – carbon dioxide in the atmosphere and higher acidity in the oceans – that eventually wiped out 90 percent of marine species and about three-quarters of land species, in a cataclysmic event 250 million years ago known as the “end-Permian extinction.” Back then, the ocean teemed with corals, algae, clams and snails. Soon after, however, there was an abrupt change to a thick layer of bacteria and limestone, a “slime-world,” dominated by bacteria. Lead author Jonathan Payne, an assistant professor of geological and environmental sciences at Stanford, said the calcium found in limestone from Guizhou Province in southeast China helps answer a question scientists have been debating for decades: What caused the mass extinction? … “Our best geologically supported idea is that the carbon dioxide release is related to the Siberian Traps volcanoes,” Payne said. Payne calculated that the eruptions, which lasted upward of a million years, released 13,000 to 43,000 gigatons (1 gigaton equals 1 billion tons) of carbon in the atmosphere. By comparison, scientists estimate we would release an estimated 5,000 gigatons of carbon if we used up all the fossil fuels in the Earth. …

Stanford scientists link ocean acidification to prehistoric mass extinction via Ocean Acidification