The Hole in the Sky: What Hope for the Ozone Layer?

Robert deZafra, SUNY Stony Brook

Abstract
In 1970's the first warnings were sounded that the continued production and widespread use of man-made chlorofluorocarbons (CFCs) could, if unchecked, lead to relatively small, but significant thinning of the Earth's protective ozone layer by the first decades of the 21st century. By 1978, the first steps were taken to limit use of CFCs in the US and a few other countries. In the mid-1980s, the Antarctic "Ozone Hole" was discovered, far worse in its present local effects than the direst predictions made in the 1970s for the distant future. This spurred international cooperation to ban the further use of CFCs.

Through the decade of the 1990s, continued research and monitoring revealed a general thinning of the total ozone layer in both northern and southern hemispheres, well away from polar regions, that was persisting over a span of 2 decades. This thinning has reached a value considerably in excess of that originally predicted for the 21st century, despite an effective worldwide ban on most CFC production and use put into place during the early 1990s. I will discuss the chemistry and dynamics behind the polar 'ozone hole' phenomenon, how research in this Department has confirmed the role CFCs play in the destruction of ozone and the formation of ozone holes. I'll also discuss whether the international treaties severely limiting CFCs are having the desired effect, and if so, why ozone loss has continued for so long.

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