Abstract. This model study addresses the change in pelagic calcium carbonate production (CaCO 3 , as calcite in the model) and dissolution in response to rising atmospheric CO 2 . The parameterization of CaCO 3 production includes a dependency on the saturation state of seawater with respect to calcite. It was derived from laboratory and mesocosm studies on particulate organic and inorganic carbon production in Emiliania huxleyi as a function of pCO 2 . The model predicts values of CaCO 3 production and dissolution in line with recent estimates. The effect of rising pCO 2 on CaCO 3 production and dissolution was quantified by means of model simulations forced with atmospheric CO 2 increasing at a rate of 1% per year from 286 ppm to 1144 ppm over a 140 year time-period. The simulation predicts a decrease of CaCO 3 production by 27%. The combined change in production and dissolution of CaCO 3 yields an excess uptake of CO 2 from the atmosphere by the ocean of 5.9 GtC over the period of 140 years.