[
Tuesday, October 18, 2005 AFP ]
GENEVA:
This year's seasonal ozone hole over Antarctica was the third largest on record,
but forecasters are uncertain how it will behave in the future, the World
Meteorological Organisation (WMO) said Tuesday.
The hole peaked last month at almost 27 million
square kilometers (10.4 million square miles), and then began shrinking as
usual, the WMO said in a statement. That was just short of the record 28 million
square kilometers (10.81 million square miles) set in 2003, the WMO said.
The second-largest hole was logged in 2000.
"Because of uncertainties linked to climate change, we don't know if we
reached the biggest ozone hole ever in 2003 or if it will be bigger sometime in
the future," said WMO ozone expert Geir Braathen. "But it's not likely
that it will get much bigger.
It seems like we have reached a plateau."
"The question is how long it will take before we get back to pre-ozone hole
levels," he told reporters. The hole in the ozone layer, discovered in the
1980s, is created by atmospheric conditions and pollution, and fluctuates
according to season and prevailing weather.
Ozone, a molecule of oxygen, is a stratospheric
shield for life on Earth, filtering out dangerous ultraviolet rays from the Sun
that damage vegetation and can cause skin cancer and cataracts. The protective
layer has been increasingly damaged by man-made chemicals, especially bromine,
chlorine and chlorofluorocarbons (CFCs).
CFCs are an aerosol gas, previously used in
refrigerators, whose use was belatedly controlled by an international treaty,
the Montreal Protocol signed on September 16, 1987.