Nature:
The hole in the ozone layer over Antarctica is starting to
heal, say researchers in Australia, who have published their
findings
in
Geophysical Research Letters. Thanks to the Montreal
Protocol of 1989, which banned the use of chlorofluorocarbons
and other ozone-destroying chemicals, levels of anthropogenic
ozone depleters detected in the region's stratosphere have been
falling since around the turn of the millennium, writes James
Mitchell Crow for
Nature. Before Murry Salby, an environmental scientist
at Macquarie University in Sydney, Australia, and his
colleagues could investigate manmade ozone depletion, however,
they first had to account for the naturally occurring annual
fluctuation in ozone levels. The researchers found that average
springtime levels are linked to changes in a particular pattern
of stratospheric weather known as dynamical forcing. Once they
figured that out, they were able to detect the gradual recovery
of the ozone levels, which had declined precipitously until the
late 1990s before beginning a slow rebound. A complicating
factor in predicting future ozone levels will be the influence
of climate change, said David Karoly, a climate scientist at
the University of Melbourne, Australia.
