Word: cfcs
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...result of an atmospheric assault by man- made chemicals called chlorofluorocarbons, which are commonly used in refrigerators and air conditioners. Soon after this disturbing surprise, the diplomats of the world were at the negotiating table. By 1987 they had reached a preliminary agreement to phase out production of CFCs, and by 1990 they had set 2000 as the target year for a total ban. Now most countries expect to beat that deadline by many years because substitutes for CFCs are coming on line more rapidly than expected. The central player in the drama -- the unwitting villain turned hero...
There is only one problem with this fabled success story: the rescuers may have arrived too late. No matter how quickly manufacturers halt the production of CFCs, billions of pounds of the chemicals already produced will continue to seep into the atmosphere and rise inexorably to attack the ozone layer. Worse, measurement after measurement since the mid-1980s has shown that ozone loss has been greater and more rapid than scientists predicted. Last month in Science magazine, researchers disclosed new satellite readings showing that in 1992 the average concentration of ozone in the upper atmosphere around the globe...
...amount of CFCs in the atmosphere will keep rising until at least the year 2000; after that it may slowly fall, but ozone destruction will continue for several decades in the 21st century. Some optimistic scientists predict that the impact on the heavily populated middle latitudes will be tolerable: at worst, a 6% ozone loss during the summer months, which could cause a 12% increase in ultraviolet radiation. But these forecasts are based on the same computer models that have consistently underestimated the problem. Given the volatile and poorly understood chemistry of the upper atmosphere, no one can predict...
Production of cfcs -- the chemicals that attack earth's precious atmospheric ozone layer and are being phased out by international agreement -- is falling even faster than expected. That's the good news. The bad news is that cfcs already released are still drifting up through the atmosphere. New satellite data, reported in the current Nature, show that ozone levels over some northern parts of Canada, Scandinavia and Russia were 10% lower this winter than they were just one year...
Since ozone loss can increase the amount of ultraviolet radiation reaching earth's surface, the risk of skin cancer may be rising in northern latitudes, as it probably is in southernmost climes. Scientists hope the level of cfcs in the upper atmosphere will peak around the year 2000 and then diminish. What they don't know is how much ozone will be left, whether the areas of severe ozone depletion will expand toward population centers, and how dangerous a 21st century day in the sun will...