From Bjerrum plots, it is found that a decrease in the salinity of an aqueous fluid will act to increase the value of the carbon dioxide-carbonate system equilibrium constants, (pK*). This means that the relative proportion of carbonate with respect to carbon dioxide is higher in more saline fluids, e.g. seawater, than in fresher waters. Of crucial importance for paleoclimatology is the observation that an increase in salinity will thus reduce the solubility of carbon dioxide in the oceans. Since there is thought to have been a 120 m depression in sea level at the last glacial maximum due to the extensive formation of ice sheets (which are solely freshwater), this represents a significant fractionation towards saltier seas during glacial periods. Correspondingly, this will cause a net outgassing of carbon dioxide into the atmosphere because of its reduced solubility, acting to increase atmospheric carbon dioxide by 6.5‰. This is thought to partly offset the net decrease of 80-100‰ observed during glacial periods.