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Two Ozone Holes
12/03/2002
Listen in RealAudio 
Hi, I'm Bryan Yeaton, and this is The Weather Notebook's weekly segment on global climate
change.
For almost twenty years now, we've been fretting about the ozone hole. It was back in 1985
when scientists discovered that the ozone was vanishing each spring in the stratosphere over
Antarctica. Ozone is nothing more than three atoms of oxygen. When it forms near the ground,
ozone is bad for our health, but in the stratosphere there's a constant layer of ozone that
helps keep the sun's ultraviolet rays from zapping us too strongly. That's why the ozone hole
was such an ominous finding.
This September we got another shocker from the Antarctic. This time, satellites showed the
ozone hole splitting in two. And the total area was much smaller than it's been since the
Eighties. Typically, the ozone hole forms each year when sunshine returns to the South Pole.
The sunlight interacts with special clouds that form only in the cold polar winter, and with
industrial chemicals called chlorofluorocarbons, or CFC's. The United Nations agreed in 1987
to phase out these chemicals, and the amount of CFC's is just now starting to level off in the
stratosphere.
But there's more to this year's incredible splitting ozone hole. Actually, you could blame
the weather. Usually a wintertime vortex spins around the pole and keeps the ozone hole
distinct. That vortex broke down early this year which in turn disrupted the ozone breakdown.
Still, even a chopped-up ozone hole can do a lot of damage. Each day in October, the hole
consumed more than 15 million tons of ozone. That's almost the weight of everyone in the U.S.
combined.
Bob Henson, author of "The Rough Guide to Weather," contributed today's story. Our special
series on global climate change is supported by the New England Science Center Collaborative
and the Roy A. Hunt Foundation.
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