Ocean acidification and the Permo-Triassic mass extinction

Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

Clarkson M. O., Kasemann S. A., Wood R. A., Lenton T. M., Daines S. J., Richoz S., Ohnemueller F., Meixner A., Poulton S. W. & Tipper E. T., 2015. Ocean acidification and the Permo-Triassic mass extinction. Science 348(6231):229-232. Article (subscription required).

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