Path to the Montreal Protocol

SUSANA DIAZ

Montreal, Canada

Conferencia; 20th Anniversary of the Montreal Protocol, “Celebrating 20 Years of Progress”; 2007

United Nations Environmental Programme

Panelista Invitada The Montreal protocol was achieved via two parallel processes. One was the evolution of the scientific understanding of the problem and the other the development of stratospheric ozone depletion policies. Concern about the depletion of stratospheric ozone first emerged over the topic of water vapor and nitrogen oxide emissions from a projected commercial fleet of supersonic aircrafts. In 1974, Sherwood Rowland and Mario Molina  found that once CFC molecules reach the middle stratosphere they are broken apart by ultraviolet light, releasing chlorine atoms, which could potentially affect the ozone layer. After that, public concern about CFCs destroying the ozone layer arose, associated with the property of this gas of filtering ultraviolet-B (UV-B) solar radiation, which is related  to non-melanoma skin cancer. From a scientific point of view, however, the impact of ozone depletion on the environment presents a much broader spectrum of concerns. During the late 1970’s several countries banned the use of CFCs as aerosols propellants. Nevertheless, ozone depletion was a global problem, and there was growing consensus that the development of international actions was the only effective response. Then, the problem of stratospheric ozone depletion moved from national to international. In the middle 80s, a strong depletion in total ozone during spring, over Halley Bay, was discovered. This finding originated new questions to the scientific community, but it also created the idea in policy makers and the public that something serious was happening to the planet and that corrective measures should be implemented. The discovery of the ozone hole over Antarctica contributed to the perception of global scale problems, with latent impact on the environment. In 1985, the Vienna Convention was held, legitimizing stratospheric ozone depletion as an international issue, and establishing the framework for the negotiation of a protocol. At that moment, the scientific understanding of the ozone issue was a key factor in the agreement for the negotiation of a protocol. During 1986 and 1987, the National Ozone Experiments (NOZE) I and II, were conducted. The results of these campaigns provided the first evidence that the chemistry of the Antarctic stratosphere was highly perturbed. In spring 1987, the Airborne Antarctic Ozone Experiment (AAOE) was performed with base in Punta Arenas. A key experiment included in the campaing showed an ozone loss, as concentrations of chlorine oxide increased. On 16th September 1987, almost at the same time the campaign was being carried out, the Montreal Protocol on Substances that Deplete the Ozone Layer was first signed. The Protocol constitutes a landmark treaty since it is the first international agreement in which decision-makers decided to take major actions to relieve a global issue, without conclusive evidence and before serious effects on health and ecosystems would have been detected.