The present annual rate of anthropic emission of CO2 amounts to 6 Gtons of carbon. It appears that about 3 Gtons are reabsorbed into the ocean. There­fore about 3 Gtons contribute to increasing the CO2 concentration in the

atmosphere. Climatic models [25, 26] show that atmospheric concentration stabilization of CO2 can be stabilized only if anthropic emissions are reduced below 3 Gtons. Figures 2.3 and 2.4 illustrate this.

Figure 2.3 shows that emission rates much below the present value are required to obtain a stabilization of the CO2 concentration. Examination of figure 2.4 shows that this stabilization will take a long time to be established. For example, in the S450 case (stabilization of the concentration at 450ppmv) the stabilization occurs only after year 2075, although the emissions decrease as soon as 2020. For the S750 case the corresponding dates are 2200 and 2070 respectively.