Threat to Ozone Layer

By George Cheriyan

SEPTEMBER 16 is observed as the International Day for the preservation of the Ozone layer. Beginning in 1995, this day is observed, commemorating the date in 1987, on which the Montreal Protocol on ‘Substance the deplete the Ozone layer’ was signed. The ozone layer absorbs most of the harmful ultra-violet-B radiation from the sun. It also completely screens out lethal UV-C radiation. The ozone shield is essential. Depleting the ozone layer allows more UV-B to reach the earth.

Causing Depletion

The ozone layer over the Antarctic has steadily weakened since measurements started in the early 1980s. The problem is worst over this part due to the extremely cold atmosphere and the presence of polar stratosphere clouds. In September 2000, the area of the ozone hole reached a record 29 million sq. kilometers. This year, the area of the ozone hole has been about 25 million sq. km. While no hole has appeared elsewhere, the Arctic, spring has seen the ozone layer over the North Pole thin up by to 30%, while the depletion over Europe and other high latitudes varies between 5% and 30%.

Gaining Attention

A meeting of experts on the ozone layer was convened in 1977, after which UNEP and the World Meteorogical Organization (WMO) set up the Coordinating Committee of the Ozone Layer (CCOL) to periodically assess ozone depletion. Inter-governmental negotiations for an international agreement to phase out ozone depleting substances started in 1981 and concluded with the adoption of the Vienna Convention for the Protection of the Ozone Layer in March 1985. The Montreal Protocol on ‘Substances that Deplete the Ozone Layer’ was adopted in September 1987. Following the discovery of the Antarctic ozone hole in late 1985, governments recognised the need for stronger measures to reduce the production and consumption of a number of CFCs and several Halons. The Montreal Amendment of 1997 finalized the schedules for phasing out methyl bromide. The Beijing Amendment of 1999 included Bromo-chloro methane. It also introduced production controls on HCFCs (Hydro-chloro-flouro-carbons) as well as controls on trade with non-Parties.

Inherent Risks

Without the Protocol, by the year 2050 ozone depletion would rise to at least 50% in the northern hemisphere’s mid latitudes and 70% in the southern mid latitudes, about 10 times worse than current levels. The implications of this would have been horrendous: 19 million more cases of non-melanoma cancer, 1.5 million cases of melanoma cancer, and 130 million more cases of eye cataracts. Ozone protection has been possible because science and industry have been able to develop alternatives to ozone depleting chemicals. Developed countries have ended the use of CFCs faster as anticipated. Substitutes have proved important in electronics.

Environmental Effects

Studies continue to confirm the adverse effects of UV-B radiation on the eyes, skin and immune system, including cortical cataract and skin cancer. Recent results continue to confirm the general consensus that solar UV negatively affects aquatic organisms. Global warming and enhanced UV-B radiation interact to affect a range of biogeochemical process including microbial activity, nutrient cycling and greenhouse gas emissions from soils.

Remaining Challenges

Unfortunately, while most governments have ratified the Protocol, ratification of the amendments and their stronger control measures lag behind. Eleven countries have yet not ratified the ozone treaties, and many more have yet not ratified the London, Copenhagen, Montreal and Beijing Amendments. Some countries with economies in transition are having difficulty in complying with the Montreal Protocol.

In the US, CFCs are heavily taxed and the market price is high. As a result, some traders illegally sell new CFCs in the industrial countries every year in the guise of recycled substances or as exports to developing countries. In some countries CFCs are being replaced by HFCs, which have a large global warming potential.

The writer is director of the NGO CUTS International, Jaipur.