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For
the Ozone Layer, a New Look Check
out the satellite photo at http://www.nytimes.com/2002/10/08/science/earth/08OZON.html 10.10.02 But federal scientists
say the condition is most likely temporary and probably has nothing to do with
the international ban on chemicals that deplete the ozone layer, which shields
the planet from harmful solar radiation. The hole, actually a
broad area of low ozone concentrations caused by chlorofluorocarbons and other
synthetic compounds that destroy ozone, forms in September and October. At its peak this year, it covered six million square miles,
down from an average of nine million over the last six years. But this is probably
because of an unusual confluence of events, said scientists at NASA's Goddard
Space Flight Center in Greenbelt, Md., in particular, warm temperatures around
the edges of the vortex of high-altitude winds at the pole. In late September, stratospheric
turbulence split the ozone gap into two lobes, a condition not seen since
satellite observations of the atmosphere began in the early 1970's. Still, the outlook is
favorable. With long-lived ozone-destroying chemicals banned under the Montreal
Protocol of 1987, the hole should shrink and disappear by 2050 or so,
scientists say. |
