Antarctic ozone hole larger than ever
Web posted at: 8:03 p.m. EDT (0003 GMT)
(CNN) -- The Antarctic ozone hole -- a threadbare patch in the Earth's protective ozone blanket -- has grown thinner and wider during Antarctica's winters for the past two decades, scientists say.
The hole in the ozone layer usually peaks around October 1, the beginning of Antarctic spring, and this year was no exception.
"The ozone hole is actually bigger than the entire continent of North America this year, and that's a record," said Paul Newman, an atmospheric physicist with the National Aeronautical and Space Administration (NASA).
"It's about five percent larger than what we saw back in 1996," Newman said.
NASA keeps tabs on the ozone layer with a satellite-borne instrument called the total ozone mapping spectrometer, or TOMS.
Stratospheric ozone, which forms a protective shield against biologically harmful ultraviolet sunlight 6 to 18 miles above the Earth, was long taken for granted. But research in the 1970s revealed that manmade chlorofluorocarbons, or CFCs, were rapidly depleting the ozone layer.
When CFCs rise high into cold air, they break down and release ozone-killing chlorine. Chlorine destroys ozone by plundering its oxygen atoms.
"Generally, the ozone hole remains close to the (South) Pole, so for human populations, we have to keep an eye on it, and we have to be a bit worried about it, but we don't have to jump to extremes here," Newman said.
He is optimistic that the ozone hole will soon stop growing, due to recent curbs on the use of CFCs, and that it may begin to shrink by the winter of 2020.
Correspondent Rick Lockridge contributed to this report.
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