A modelling approach treating the problem of changing climate and trace gases is presented. The approach uses the atmospheric temperature and diabatic heating rate computed by the seasonal, multi-layer GLAS energy balance climate model to derive a seasonal residual circulation. The derived circulation corresponding to the present climate is found to be comparable to similar previous computations. This circulation is used to estimate air mass exchange among principal atmospheric domains. It is estimated that the mean turnover time for the air exchange between the troposphere and stratosphere is about 3.5 years and that between the two hemispheres, about 1.2 years. Sensitivities of the circulation to incoming solar radiation and CO2 concentration are investigated. As the forcings increase, the residual circulation is intensified, which implies an enhancement of the air mass exchange between the troposphere and stratosphere and between the two hemispheres. This result may have implications for atmospheric chemistry. ¿ American Geophysical Union 1995.