Image of Antarctic ozone hole (September 2006): Courtesy of NASA
The hole in ozone layer is even bigger than it was at the height of the ozone panic in the 1980s, but is better today than it would have been had the world not taken decisive action 22 years ago. It's just that the damage from chlorofluorocarbons, which deplete ozone, is going to take several decades for the Antarctic hole to close up for good. That's because the ozone-depleting gases we emitted before the Montreal Protocol are still floating around the stratosphere or making their way in that direction. Some of these gases can circulate for a century before their molecules break apart or air currents remove them from the sky.
By 1987, 24 nations had ratified the Montreal Protocol, a landmark agreement that calls for a ban on producing and using nearly 100 of the most important ozone-depleting chemicals. As of this month, with the addition of East Timor, the protocol has been ratified by every member of the United Nations.
Ozone gas (made from triplets of oxygen atoms) helps shield us from the sun's harmful UV rays. Ninety-seven percent of the substances regulated under the Montreal Protocol have now been phased out and replaced in manufacturing with more ozone-friendly alternatives, like hydrofluorocarbons (HFCs). The remaining gases will be phased out globally by 2040. According to the United Nations Environmental Programme, enactment of the protocol has prevented some 20 million cases of skin cancer and 130 million cases of eye cataracts. (Slate.com, 9/29/09)
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