PATCHING THE HOLES
Chemicals that attacka crucial part of the upper atmosphere are being phased out, and despite a black market in the compounds, earth's shield should soon be on the mend
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BY DICK THOMPSON
By most measures, the worldwide mobilization to get rid of the damaging chemicals that could obliterate earth's vital atmospheric ozone shield is one of the few bright spots in an otherwise dark environmental picture.
A healthy ozone layer blocks a large part of the sun's ultraviolet radiation, which in big enough doses can cause skin cancer and harm plant life crucial to the food chain. When scientists confirmed a thinning of the ozone in the 1980s, it was the first demonstration that humans were capable of destroying an essential component of the environment. The response was the first--and so far only--demonstration that scientists, businesses and governments could work together to prevent a global ecological calamity.
When the problem was originally suspected by scientists in the 1970s, the manufacturers of chemicals like chlorofluorocarbons (cfcs)--used in aerosol sprays, refrigerators and air conditioners--vigorously disputed the notion that their products could poke holes in the ozone. Eventually researchers pieced together proof of the connection, and in 1987 the Montreal Protocols, ultimately signed by 150 countries, began the phaseout of ozone-destroying chemicals and hastened the development of alternatives.
Now, a decade after the historic agreement, the threat has eased--but not passed. The chemicals in the cfc family are being eliminated on schedules that differ from country to country by economic status: faster in the industrialized nations, slower in the developing world. And since cfcs are long-lived compounds, gases released in the past are still attacking the ozone. This spring, satellites over the Arctic measured the lowest levels of ozone ever recorded. Meanwhile some cfcs are still sold illegally in nations like the U.S. where production was supposed to be phased out completely by now. Concludes M.I.T.'s Mario Molina, who shared a 1995 Nobel Prize for his early warning about the vulnerability of the ozone layer: "Essentially the Montreal Protocols have worked very well, but I regard this as a job to be continued."
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