Severe ozone depletion avoided

We are already reaping the rewards of the Montreal Protocol, with the ozone layer in much better shape than it would have been without the UN treaty, according to a new study in Nature. Study lead author Professor Martyn Chipperfield, from the School of Earth & Environment at the University of Leeds, said: “Our research confirms the importance of the Montreal Protocol and shows that we have already had real benefits. We knew that it would save us from large ozone loss 'in the future', but in fact we are already past the point when things would have become noticeably worse. Although the Montreal Protocol came into force in 1987 and restricted the use of ozone-depleting substances, atmospheric concentrations of these harmful substances continued to rise as they can survive in the atmosphere for many years. Concentrations peaked in 1993 and have subsequently declined. In the new study , the researchers used a state-of-the-art 3D computer model of atmospheric chemistry to investigate what would have happened to the ozone layer if the Montreal Protocol had not been implemented. Professor Chipperfield said: “Ozone depletion in the polar regions depends on meteorology, especially the occurrence of cold temperatures at about 20km altitude – colder temperatures cause more loss.