In the recent past, several studies have been focused on the effects of increased CO2 concentration on global climate. In the tropics one of the most important phenomenon is the Asian summer monsoon (ASM) whose main aspects and variability depend on the global mean state. Climate change modifies the mean state of atmosphere and ocean and as a consequence it may induce changes in the ASM and its variability. A powerful tool to study the impact of CO2 concentration on global scale phenomena, such as the ASM, are global experiments performed with coupled models. In normal conditions, the ASM exhibits substantial year to year variations. This interannual variability has been shown to be related to changes in a number of factors, such as sea-surface temperatures in the Indian Ocean, Pacific ocean or snow cover over the Eurasian continent. With this study we investigate the impact induced by climate change onto the main features of the ASM variability. To this aim a long control simulation and model scenario experiments are used. Preliminary results indicate that changes in mean climate conditions induce substantial changes in the main features of the simulated ASM.