2004
Winter 2004. The
Hole Truth. By Jill Davis for OnEarth
(NRDC). Is the
ozone layer on the mend? Perhaps. On September
24, 2003, a news bulletin arrived from outer
space. From the vantage of its 460-mile-high
orbit, the satellite Earth Probe Total Ozone
Mapping Spectrometer (TOMS) transmitted
to the Goddard Space Flight Center a deceptively
beautiful mosaic image that revealed the
latest dimensions of the ozone hole over
Antarctica. On that day, it measured 11.1
million square miles, the second-largest
such hole ever recorded. That sounds like
bad news, but around the same time that
the TOMS satellite beamed home its brilliant
snapshots, a group of scientists from the
National Oceanic and Atmospheric Administration
found reason for cautious optimism. Air
samples from Barrow, Alaska, and Cape Grim,
Tasmania, as well as other distant locales
showed that levels of bromine, a compound
that depletes ozone 45 times more efficiently
than the chlorine in chlorofluorocarbons
(CFCs), have declined 5 percent over the
last five years. The less bromine in the
earth's lower atmosphere, the less damage
done to the ozone layer in the stratosphere.
"Based on our current knowledge,
we are on course for recovery of ozone
to pre-1980 levels sometime between
2040 and 2050," says Stephen Montzka,
the study's lead researcher. The reason
for Montzka's upbeat forecast is simple:
International efforts to control compounds
that destroy ozone are working. The
Montreal Protocol, adopted in 1987 and
now ratified by 184 countries, regulates
the release into the atmosphere of ozone-eating
pollutants, including methyl bromide,
a fumigant used to kill everything from
fungi to furniture beetles. Since 1998,
industrialized nations have cut the
production of methyl bromide, a major
source of the bromine, by more than
25 percent. A full phase-out is scheduled
for January 1, 2005....
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