On Wednesday, NASA and the National Oceanic and Atmospheric Administration (NOAA) announced that warmer air temperatures above the Antarctic caused "the second smallest seasonal ozone hole in 20 years. The ozone hole, which reached its peak size on September 22, averaged 6.9 million square miles this year.
According to NOAA, the ozone hole extended to 8.2 million square miles in September, an area about the size of North America. The largest recorded ozone hole was in 2000 at 11.5 million square miles, it stated.
The Christian Science Monitor reported that ozone is a pollutant on Earth's surface but helps protect life on Earth from harmful ultraviolet (UV) radiation. UV rays can cause skin cancer and damage plants, NOAA reported.
The Antarctic ozone, which first made its yearly appearance in the early 1980s, is "caused by chlorine released by manmade chemicals called chlorofluorocarbons or CFCs," NOAA said. CFCs not only destroy ozone molecules but are also thought to linger in the stratosphere for years.
Air temperatures are thought to affect the size of the ozone hole and it is generally believed that colder temperatures equate to larger ozone holes.
Jim Butler, from NOAA's Earth System Research Laboratory in Boulder, Colo., said, "It happened to be a bit warmer this year high in the atmosphere above Antarctica, and that meant we didn't see quite as much ozone depletion as we saw last year, when it was colder."
Scientists believe that it could take another 10 years before signs of an Antarctic ozone layer recovery are detected. According to NASA atmospheric scientist Paul Newman, it is unlike that the Antarctic ozone layer returns to its early 1980s size before 2060.
This lengthy recovery time is due to "large quantity and long lifetime of ozone-depleting substances in the atmosphere," NOAA reported.
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