The Edinburgh Geological Society has a lecture on 25 November about ocean acidification.
At the boundary of the Permian and Triassic, ~252 million years ago, is the greatest mass extinction documented, where we estimate that more than 90% of Earth’s species died. The “PT” or 'Great Dying' hit marine species the hardest - killing off, for instance, the once ubiquitous trilobites.
Recent work has shown that ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for this mass extinction. We present a high-resolution seawater pH record across this interval, using boron isotope data from the UAE combined with a quantitative modelling 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.
As such, the extinction holds a cautionary lesson for today: because of CO2 released by burning fossil fuels, oceans could now be acidifying even faster than they did 250 million years ago, although the process hasn’t yet persisted nearly as long.
Details here.