Objective
Boron isotope studies and box modelling lent strong support to the hypothesis that pore water driven calcite dissolution during glacial periods can account for a significant part of the observed G-IG change in atmospheric pCO2. We propose to test the validity of this scenario by combining a down core study with numerical modelling . So far , no one has used all available proxies on the same samples to reconstruct the ocean carbonate chemistry. Such a study will help to identify natural sources and sinks of CO2. Knowledge of the nature and amplitude of fluctuations in the past can be used to assess the potential range of variations in the present ocean. Present day pCO2 increase, acidifies the ocean and reduces the calcification capacity of oceanic carbonate producers, introducing a mechanism for pCO2 decrease. We propose to quantify this negative feedback.