August 30, 2005
Ozone layer has stopped shrinking, US study finds
WASHINGTON (Reuters) - The ozone layer has stopped
shrinking but it will take decades to start recovering, U.S.
scientists reported on 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.
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
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
Weatherhead 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