Ozone Layer Has Stopped Shrinking, U.S. Study Finds
The ozone layer has stopped shrinking but it will take decades to start
recovering, U.S. scientists reported Tuesday. They said an international
agreement to limit production of ozone-depleting chemicals has apparently
worked, but the damage to ozone has not been halted completely.
An analysis of satellite records and surface monitoring instruments shows
the ozone layer has grown a bit thicker in some parts of the world, but
is still well below normal levels, the scientists report in Wednesday's
issue of the Journal of Geophysical Research.
Elsewhere, the decline in ozone levels has stabilized, said Betsy
Weatherhead, a researcher at the University of Colorado at Boulder and
the National Oceanic and Atmospheric Administration. "The observed
changes may be evidence of ozone improvement in the atmosphere," she said
in a statement.
The experts credited, at least in part, the 1987 Montreal Protocol which
was ratified by more than 180 nations and set legally binding controls
for on the production and consumption of ozone-depleting gases containing
chlorine and bromine.
The prime suspects in ozone destruction are chlorofluorocarbons, or CFCs,
once commonly used in refrigeration, air conditioning and industrial
cleaning. "These early signs indicate one of the strongest success
stories of international cooperation in the face of an environmental
threat," said NOAA administrator Conrad Lautenbacher.
Weather head noted that methane levels, water vapor and air temperatures
will continue to affect future ozone levels. "Even after all chlorine
compounds are out of the system, it is unlikely that ozone levels will
stabilize at the same levels," she said.
"Chemicals pumped into Earth's atmosphere decades ago still are affecting
ozone levels today," said Sherwood Roland of the University of California
Irvine. "This problem was a long time in the making, and because of the
persistence of these chlorine compounds, there is no short-term fix."
The ozone layer remains so thin that cancer-causing ultraviolet radiation
is still getting through. "This study provides some very encouraging
news," said Mike Repacholi of the World Health Organization. "But the
major cause of skin cancer is still human behavior, including tanning and
sunburns that result from a lack of proper skin protection."
Source: Reuters, 31 August 2005
Clean Energy NEWS
Vol. 5, Number 39, 06 September 2005