Fig. 1.

Percentage changes in average global surface ocean ion concentrations resulting from up to a fourfold change (300 % increase) in atmospheric carbon dioxide, compared with pre-industrial values. Values for atmospheric CO₂ change from 280 to 1,120 ppm; bicarbonate ions from 1,770 to 2,120 μmol kg⁻¹; carbonate ions from 225 to 81 μmol kg⁻¹; and pH from 8.18 to 7.65 (where pH is defined as the negative decimal logarithm of the hydrogen ion activity, a linear relationship is assumed between activity and concentration, and a uniform and constant upper ocean temperature is assumed, of 18 °C). From Williamson and Turley (in press)