WASHINGTON - Warm air at high altitudes this September and October helped shrink the man-made ozone hole near the South Pole ever so slightly, scientists say.
The hole is an area in the atmosphere with low ozone concentrations. It is normally at its biggest this time of year. NASA says that on average it covered 8.1 million square miles this season. That’s 6 percent smaller than the average since 1990.
The ozone hole is of concern because high-altitude ozone shields Earth from ultraviolet radiation.
NASA chief atmospheric scientist Paul A. Newman says the main reason for this year’s result is local weather. The upper air has been almost 2 degrees warmer than normal in the globe’s southernmost region. That has led to fewer polar stratospheric clouds. These clouds are where chlorine and bromine, which come from man-made products, nibble away at ozone.
James Butler, director of the global monitoring division at the National Oceanic and Atmospheric Administration’s Earth System Research Lab, said Wednesday that the new figures are “sort of encouraging news.”
“It’s not getting worse,” Butler said.
Butler said it stopped getting worse around the late 1990s.
Front Section, Pages 4 on 10/24/2013