Stratospheric ozone depletion 10 years after Montreal
October 8, 1997: September 1997 marked the tenth anniversary of the Montreal Protocol on Substances that Deplete the stratospheric Ozone Layer. The ozone layer serves as Earth’s shield from the Sun’s longer wave-length UV radiation, or ultraviolet-B. Ultraviolet-B is known to depress crop and forest growth, is a probable cause of skin cancer in humans, and is believed to affect the health and even the viability of a wide range of organisms and ecosystems.
The Montreal Protocol was the first international treaty to protect the atmosphere from the consequences of human activity. In 1987, 24 countries participated in the agreement, which aimed, by 1996, to freeze production of ozone-destroying chlorofluorocarbons (CFCs). Chlorofluorocarbons are widely used as the working fluid in refrigeration and air-conditioning systems. When signed in 1987, the treaty was considered "progressive and far-sighted" by interest groups such as Ozone Action (1). Today, however, although 162 countries, representing about 95% of the world’s population, are signatories to it, there is widespread concern that the provisions of the Protocol are insufficient.
Since 1987, stratospheric ozone depletion has continued at a steady pace. Last year, the Antarctic ozone hole was unprecedented in both duration and severity of ozone depletion (2). This year, in the Arctic, the annual minimum stratospheric ozone concentration was 45% below the historical norm based on measurements dating back to the 1950’s. At mid-latitudes, stratospheric ozone concentrations are declining at a rate of about 5% per decade (1).
Even if the provisions of the Montreal Protocol were sufficient to halt the production of ozone-depleting CFCs completely, atmospheric concentrations of chlorine- and bromine-containing compounds, which catalyze ozone breakdown, will not peak for some years (for the chemistry of ozone depletion, see Refs. 3,4 and 5). This is because of the slow migration of these substances to the upper atmosphere. As a consequence, the decline in stratospheric ozone concentrations is likely to continue, and may accelerate, for decades.
This year, at a United Nations meeting in Montreal held to mark the tenth anniversary of the Montreal Protocol, delegates grappled with new threats to the ozone layer, including resistance by agricultural interests to the phase-out of methyl bromide, a fumigant used against a broad-spectrum of pests, and the illegal trading of CFC’s. It is estimated that a phase-out of methyl bromide, which is as at least as effective as CFC in depleting stratospheric ozone, would reduce agricultural production by an estimated $1.5 billion in the U.S. alone (6). Smuggling CFCs from stockpiles and plants in developing nations, where use is still permitted, into the U.S. and other developed nations, where use is banned, has become big business. A truckload of CFCs now goes for $500,000 on the US market. In Miami smuggling of CFCs is believed to be second only to that of cocaine (7).
Despite the daunting scenario, Canada’s Environment Minister, Christine Stewart, delivered an optimistic speech at the 1997 UN meeting in Montreal (8), and presented the results of a Canadian Government study purporting to show the global economic benefit of the Montreal Protocol to be roughly $459 billion compared to its implementation cost of $235 billion. But skepticism about these claims abounds. John Passacantando from Ozone Action stated that the calculation of benefits is as realistic as assuming "everyone will drive under the speed limit." Terence Corcoran, business page commentator for the (Toronto) Globe and Mail, attacks the report's conclusions from a rather different perspective and questions whether there are any benefits to be got from the Protocol. "Why," he asks “are we are spending billions of dollars and massive regulatory effort to fight speculative diseases [i.e., caused by increased ultraviolet-B radiation] associated with speculative theories [i.e., the idea that CFCs cause ozone loss], while somebody dies every 12 seconds from a known killer--malaria” (9).
Conflict between economic and environmental interests became evident toward the end of last month's UN conference, when it seemed that negotiations over the phase-out of methyl bromide would reach deadlock. Ultimately, it was decided that developed countries would have until 2005 to phase out methyl bromide and developing countries would have until 2015. Based on experience with the regulation of CFCs, one may expect that if there is a meeting to mark the 20th Anniversary of the Montreal Protocol delegates will have to deal with the consequences of a robust trade in illegal methyl bromide.
REFERENCES and LINKS
(1) The Globe and Mail (Toronto). 1997. Ozone layer still facing threats despite controls. September 9
(2) OZONE ACTION-Media Release Why the 10th Anniversary of the Montreal Protocol was not an occasion for celebration
(3) UNIVERSITY OF CAMBRIDGE Offers excellent background to the science of ozone depletion and features a multimedia tour through an ozone hole. (Target file now deleted from Web)
(4) UNITED NATIONS-Ozone Site Provides the minutes to the Montreal Protocol as well as information regarding the science of ozone depletion
(5) Iowa State University, Institute for Advanced Physics: Slide show on CFCs and atmospheric ozone Lecture slides presenting some of the key evidence concerning the impact of CFCs on the stratospheric ozone layer. (Target file now deleted from Web)
(6) US ENVIRONMENTAL PROTECTION AGENCY-Methyl Bromide Information Site A detailed site featuring everything you need to know about methyl bromide and more
(7) DEADLY COMPLACENCY Written for Ozone Action, a report on CFCs in the black market.
(8) ENVIRONMENT CANADA-Ozone Page This site offers coverage of the Montreal Protocol from the host country's perspective
(9) Terence Corcoran. 1997. Ozone crime wave. The Globe and Mail (Toronto), September 12