The response of the atmosphere to emissions of chlorofluorocarbons (CFCs) and other chlorocarbons and to increasing concentrations of other radiatively active trace gases is calculated by means of a coupled chemical-radiative-transport one-dimensional model. It is shown that significant reductions in the ozone concentration and in the temperature should be expected in the upper stratosphere as a result essentially of increasing concentrations of active chlorine produced by photodecomposition of the CFCs.