NASA study predicts uneven ozone recovery

BALTIMORE, April 14 (UPI) -- The U.S. space agency says the Earth's ozone layer should eventually recover from damage caused by chlorofluorocarbons but it has been changed forever.

New research by National Aeronautics and Space Administration scientists suggests the ozone layer of the future is unlikely to look much like the past because greenhouse gases are changing the dynamics of the Earth's atmosphere by altering the circulation of stratospheric air masses from the tropics to the poles.

NASA researchers said that, in Earth's middle latitudes, means ozone is likely to "over-recover," growing to concentrations higher than they were before the mass production of CFCs. In the tropics, stratospheric circulation changes could prevent the ozone layer from fully recovering.

"Most studies of ozone and global change have focused on cooling in the upper stratosphere," said Feng Li, a NASA atmospheric scientist at the Goddard Earth Sciences and Technology Center at the University of Maryland-Baltimore. "But we find circulation is just as important. It's not one process or the other but both."

The study model also showed a continuing ozone deficit in the stratosphere over the tropics. In fact, when the model run ended at year 2100, the ozone layer over the tropics still showed no signs of recovery.

The research appeared in the March issue of the journal Atmospheric Chemistry and Physics.