An important uncertainty in coupled chlorine–carbon dioxide studies of atmospheric ozone modification

Abstract

There has been considerable interest recently in changes in the composition of the stratosphere following the suggestion by Molina and Rowland1 that certain fluorocarbons could ultimately lead to ozone destruction. This interest has increased since the discovery in 1985 of large ozone decreases over Antarctica2. It is now known that many species have the potential to modify the stratospheric ozone distribution either directly, by photochemical processes, or indirectly, through changes in atmospheric temperature by modification of the transmission of infrared radiation. Here we present calculations using a two-dimensional atmospheric model of the effect on stratospheric ozone of increases in the atmospheric abundances of CO2 and various chlorine-containing compounds. We have carried out such calculations previously3 but changes in the kinetic data used in the model have led to very significant differences in the calculated ozone modification. In particular, the lower stratosphere, a difficult region to model, now plays an even more crucial role in the vertically integrated ozone depletion. We believe that uncertainties in the thermal response of the lower stratosphere represent a significant limitation in our ability to predict future states of the middle atmosphere.