Assessment of the effect of the Montreal Protocol on atmospheric ozone

Ozone depletion is a major global scientific and environmental problem. One of its causes is the anthropogenic increase of CFCs in the atmosphere, whi ch results in the enhancement of the concentration of reactive chlorine in the stratosphere. To reduce the influence of anthropogenic ozone-depleting substances, the Montreal Protocol was agreed by Governments in 1987, with s everal Amendments adopted later. What has been the result of the Montreal P rotocol and its Amendments (MPA)? Here we present the first 3D-model assess ment of the effect of the MPA on atmospheric ozone which has been performed with the University of Illinois at Urbana-Champaign (UIUC) Atmospheric Che mical Transport Model (ACTM). We find that the MPA has saved up to 2% of th e present-day total ozone in the Northern Hemisphere and about 5% in the So uthern Hemisphere. Our calculations also show that CFCs do not play the maj or role in the observed recent total ozone variations.