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Third Largest Ozone Hole over Antartica
Largest Ozone Hole over Antartica after 2000 and 2003, but we don't know the effect
Geneva: This years' seasonal ozone hole over Antarctica
was the third largest till now, but forecasters as in the
past cannot estimate its behaviour in the future, the World
Meteorological Organisation (WMO) said Tuesday.
Largest Seasonal Ozone hole before this
was observed in 2003, it was 10.81 nearly 11 Million square
miles that was almost as big as land of whole United States.
This year as per the World Meteorological Organisation (WMO)
recordings it is 10.4 just 28 million square kilometers
less.
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. "As the amount of chlorine and
bromine will continue to decline over the next decade --
very slowly -- one expects the ozone whole to get smaller
and smaller," Braathen said.
"But at the same time there is also
this issue of climate change, which leads to high temperatures
on the ground while in the stratosphere temperatures will
decrease. And that will encourage more ozone loss in the
Arctic and Antarctic."
"This is an open question. We don't
know what the effect will be." Largest Ozone Holes
ever
2000 11.50 Million square miles
2003 10.81 Million square miles
2005 10.40 Million square miles
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