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It seems there's finally some good news for the ozone layer. According to a report that will appear in an upcoming issue of the Journal of Geophysical Research - Atmospheres, the rate at which ozone is disappearing in the upper stratosphere is slowing. The findings highlight the success of a worldwide reduction in harmful chlorofluorocarbons (CFCs).
The 1995 Nobel Prize in Chemistry was awarded for the discovery that chlorine released into the atmosphere by CFCs, used mainly as refrigerants and aerosol propellants, destroyed the planet's protective ozone layer. An international ban on the chemicals followed. Michael Newchurch of the University of Alabama in Huntsville and his colleagues examined data from three NASA satellites and ground stations located around the world to study the state of the ozone layer. "We're not gaining ozone but we're losing it less quickly," Newchurch reports. "And the amount of chlorine in that layer of the stratosphere has not yet peaked, but it has slowed down significantly, so we should start to see some ozone improvement in the coming years."
The findings do not put the ozone layer in the clear, however. For one, improvements were seen only in the upper stratosphere. "We don't see compelling evidence that the destruction of ozone is slowing the lower stratosphere, where 80 percent of the protective ozone layer exists," Newchurch says. That's because factors in addition to chlorine, such as greenhouse gases and changing wind currents, alter the ozone layer at lower altitudes. But Newchurch notes that the results are a promising beginning for an ozone layer recovery.