The coupled general circulation model developed in the european project SINTEX has been used to assess the impact of rising levels of CO2 concentration on the interannual tropical variability. Under present climate parameters, the model has been shown to have a realistic description of the ENSO dynamics in the equatorial Pacific.

In this study the coupled model has been used to assess the impact of several levels of CO2 in equilibration experiments up to 16 times the present values of CO2. For each case the experiments were performed for about 100 years and equilibration of the upper ocean was reached.

The details of the response of the equatorial ocean and of the equilibration processes are discussed.