Seven miles above the earth in an atmospheric region known as the stratosphere, a layer of slightly bluish gas called ozone—a form of oxygen —protects the planet from more than 90 per cent of the sun’s destructive ultraviolet rays. Scientists have known for more than a decade that the ozone layer is thinning—particularly over Antarctica, where there is a seasonal loss of up to 40 per cent in an area about twothirds the size of Canada. And they have placed the blame largely on chlorine molecules contained in manmade chemicals called chlorofluorocarbons (CFCs). But an international panel of 100 scientists organized by the U.S. National Aeronautics and Space Administration (NASA) has now released alarming results: ozone loss over populated regions of the Northern Hemisphere appears to be far greater than earlier evidence had demonstrated. Declared NASA scientist Michael Prather, a panel member who is preparing a report on the future of stratospheric ozone: “It could be that we are underpredicting the effect of chlorine.”
About one billion kilograms of CFCs, contained in such products as refrigerator coolants, aerosol sprays, foam insulation and plastic fast-food containers, are produced annually. Much of it finds its way into the environment and gradually drifts into the stratosphere. There, searing ultraviolet radiation breaks apart the normally stable CFCs, releasing chlorine, which acts as a catalyst in the destruction of ozone. As the ozone dissipates, more of the sun’s ultraviolet rays reach the earth’s surface—potentially causing massive increases in skin cancer, crop devastation and serious damage to the aquatic food chain.
In an effort to halt CFC emissions, representatives from 24 countries—including Canada—signed a treaty last September in Montreal which committed the world’s industrialized nations to reduce CFC production to 1986 levels
within three years and to halve those quantities by 1999. But that agreement was based on information that panel members now say is outdated. The scientists say ground-based instruments show that a belt of ozone over the Northern Hemisphere, an area that encompasses most of the populated regions of Canada, has decreased by three per cent during the past 20 years—not the one per cent that earlier data showed. And instead of a fur-
ther projected ozone loss of one to two per cent in that belt during the next 30 years, Prather said panel members believe that the depletion may be as high as four per cent.
Scientists calculate that each oneper-cent loss of ozone results in a twoper-cent increase in the amount of ultraviolet radiation reaching the earth. Those additional rays have the capacity to cause thousands of skin-cancer deaths as well as severe damage to world crops and to plankton—tiny organisms in the ocean, upon which many higher orders of sea creatures feed.
As a result of the new data, such environmental action groups as the Ottawa-based Friends of the Earth are calling for 85-per-cent cutbacks in CFC production within five years. That is because scientists have established that it takes up to 10 years for CFCs to
reach the stratosphere—and that they can remain aloft, causing damage, for more than 100 years. Simply because of the chemicals currently in the atmosphere, environmentalists say the future of the ozone layer—and, indeed, all animal and marine life—is in jeopardy. Said Prather: “The Montreal protocol was an incredible and optimistic first step in controlling the global environment. But we need a political and scientific reassessment.”
Experts say that there are no stopgap solutions to the problem and that only long-term reduction of CFCs will allow the ozone layer to replenish itself. Still, governments are not yet in a position to enforce the terms of the Montreal agreement. In order to take effect, the treaty must be ratified by 11 nations accounting for at least twothirds of CFC production worldwide. And to date, only the United States— which alone produces 29 per cent of the world’s CFCs—and Mexico have done so. According to Victor Buxton, who is chief of the chemical controls division of Environment Canada and who was a Canadian negotiator in Montreal, bill C-75, currently before the House of Commons, includes the treaty’s CFC restrictions as part of a comprehensive environmental protection measure. It is expected to become law by the end of the month. And Bux-
ton says he believes that the 50-percent cutback requirements will result in much broader changes within the $2.75-billion worldwide industry. “It is important to recognize that industry will see that there is no market growth in the restricted chemicals, and that they will have to find substitutes for them,” he said.
Indeed, in anticipation of that development, major CFC producers have stepped up research into alternatives. Mississauga, Ont.-based Du Pont Canada Inc., for example, has spent $10 million over the past three years honing industrial applications for CFC substitutes developed by its U.S. parent company, E. I. du Pont de Nemours & Co. Inc.—the world’s largest producer of CFCs. The new chemicals either break down more quickly than the problem CFCs, preventing them from reaching the stratosphere in the same quantity, or they do not contain the dangerous chlorine. As a result, they pose less of a threat to the ozone layer. Still, they are more expensive to produce—and their industrial applications are limited. As well, experts caution that because they are less stable than the older chemicals, they may pose new dangers to human health.
For his part, Buxton said that, although the new chemicals may reduce ozone depletion, they should be viewed merely as a first step toward solving the ozone problem. The Montreal agreement places limits on only five specific CFCs. At the same time, demand for the unrestricted CFCs and the new, less harmful chemicals is increasing as industry finds new applications for them. Consequently, Buxton said, despite attempts to control CFCs, ozone damage may actually increase. “We must monitor the growth and use of these new chemicals closely. They are part of the solution to the problem in the short term, but they are not a long-range cure,” he said.
Complicating the issue is the effect of the sun itself on the ozone layer. The sun is entering an 11-year cycle, which scientists say will help reduce the depletion of ozone. But they hasten to add that any resulting increase in ozone levels will be temporary. Said Guy Fenech, a meteorologist at Environment Canada: “The CFC manufacturers are waiting to say, ‘See, CFCs have nothing to do with the ozone layer—it’s replenishing itself naturally.’ ” But despite the confusion over their data, many scientists agree that the atmosphere has given off significant warning signals—and that governments and industry must heed them in order to ensure the safety of life on this planet.
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