The end-Permian extinction was a geologically abrupt (~ 100 000-year duration) event that occurred ~ 252 million years ago (Ma) (Burgess et al., 2014; Joachimski et al., 2012; Shen et al., 2011; Sun et al., 2012). The main phase of the extinction event was characterized by 8 to 10 _C of global warming (Joachimski et al., 2012), driven by the massive release of greenhouse gases, as reflected in a contemporaneous negative C isotope excursion (CIE) of ~ 6‰ (Shen et al., 2011) in the ocean. This suggests that either the source or its oxidation product was CO2. Recent analyses of calcium isotopes of marine sediments and the pattern of extinction selectivity (Clapham and Payne, 2011; Hinojosa et al., 2012; Payne et al., 2010), and volatile studies on melt inclusions from the Siberian Traps (Black et al., 2012; Black et al., 2014), suggest that the Siberian Traps volcanism might be the trigger for the end-Permian extinction. Besides global warming, one other consequence of CO2 emission is ocean acidification, known as “the other CO2 problem” (Doney et al., 2009). Rising atmospheric CO2 causes a decrease in ocean pH and adjustments in carbonate chemistry, leading to a reduction in carbonate ion concentration and the saturation state of calcite and aragonite (Zeebe, 2012). In addition to impacts on their physiology, calcifying organisms are also susceptible to dissolution of their carbonate skeletons (Kleypas et al., 2006; Turley et al., 2010).