SIMULATION OF THE EFFECT OF CARBON-DIOXIDE DOUBLING ON STRATOSPHERIC OZONE

Two 5-year climate simulations have been performed with a general circulation model including a representation of stratospheric ozone for present conditions and.for conditions corresponding to a doubling of the atmospheric concentration of carbon dioxide. Comparison of these two simulations allow one to show, in addition to the tropospheric warming connected to the greenhouse effect of CO2, a cooling increasing with height in the stratosphere, and an increase of the ozone concentration due to modifications of the photochemical reaction rates. These results confirm and complement the conclusions drawn from previous studies made with two-dimensional photochemical or dynamical models and also show that to forecast the polar ozone evolution the heterogeneous chemical processes must be taken into account.