Ozone Depletion by Chlorofluoromethanes? Yet Another Look

Abstract

A number of predictions of stratospheric ozone depletion caused by release of chlorofluoromethanes (Freons 11 and 12) into the atmosphere are described and the wide variation of predicted depletion noted. By using techniques frequently used in meteorology it is found that during the period 1958 to 1975 the long-term trend of ozone shows a net increase of 4%. Chlorine-bearing compounds which have been released into the atmosphere since 1950 are estimated as of 1975 to have an effect of 20% as great as the final effect if release of chlorofluoromethanes is continued at the 1973 rate until equilibrium is reached. The upward ozone trend during a time of active release of chlorine-bearing materials seems to contradict the ozone depletion theory. Reasons for the contradiction are discussed.