In recovery
Ozone hole on the mend
Scientists may have already spotted the annual Antarctic ozone hole, shown here in September 2006
Scientists may have spotted Antarctica's ozone hole on the road to recovery, at least a decade sooner than they thought healing would be noticeable. In 1989, an international agreement called the Montreal Protocol began phasing out chemicals that have gnawed away at Earth's protective ozone layer. Most researchers thought it would take until at least 2023 to detect the hole's slow recovery, but researchers in Australia now claim to have seen ozone ticking upward since the late 1990s. "The key is to account for large year-to-year fluctuations that have obscured a gradual increase in the long-term evolution of ozone," says atmospheric scientist Murry Salby of Macquarie University in Sydney. His team published its findings online May 6 in Geophysical Research Letters. First spotted in 1985, the Antarctic ozone hole was quickly linked to chemicals called chlorofluorocarbons, emitted mainly in the Northern Hemisphere but concentrated over the South Pole by atmospheric circulation patterns. Chlorine atoms from these CFCs react with ozone molecules, seasonally destroying the layer that shields Earth from cancer-causing and crop-damaging ultraviolet radiation.
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