New findings of scientists from several universities published in Science show that the Permian-Triassic mass extinction (~ 252 million years ago), the greatest extinction event of all time, was caused by ocean acidification. The researchers studied boron isotopes from marine sediments in order to reconstruct seawater pH and subsequently combined these data with quantitative modeling techniques to develop a scenario for the mass extinction. Their results show that seawater pH remained relatively stable during the first phase of the extinction, but rapidly shifted to more acidic values during the second phase, which lasted ~ 10 thousand years. This acidification of the oceans had dramatic consequences for life on Earth and is thought to be associated with the release of massive amounts of carbon, related to the volcanism of the Siberian Traps. Up to 96 % of living marine species became extinct during the Permian-Triassic mass extinction and now, it has been shown for the first time that ocean acidification was the responsible mechanism.
Journal reference: Clarkson, M. O., Kasemann, S. A., Wood, R. A., Lenton, T. M., Daines, S. J., Richoz, S., … & Tipper, E. T. (2015). Ocean acidification and the Permo-Triassic mass extinction. Science, 348(6231), 229-232.
Image: Eruption of the Tavurvur volcano on February 13, 2009 near Rabaul, New Britain, Papua New Guinea. Source: Taro Taylor, Wikimedia Commons.