19 October 2005The Courier-Mail
Depletion of the ozone layer above Antarctica, caused by emissions of industrial chemicals, seems to have peaked, indicating that global environmental pacts were working, UN scientists said today.The seasonal hole above the South Pole and Antarctica is now shrinking after falling short of the record years of 2003 and 2000, the United Nations' World Meteorological Organisation (WMO) said in its latest bulletin.
It peaked at 26.9 million sq kms on September 19, it said, against 29 million sq km in September 2003, which most scientists say was the record.
"It is the third largest ever, more or less as one would expect from present levels of chlorine and bromine in the atmosphere," Geir Braathen, WMO's top ozone expert, told a news briefing.
"It doesn't look as if the ozone hole is going to get any bigger (in coming years). It seems like we have reached a plateau...," he said.
Chlorofluorcarbons (CFCs) containing chlorine and bromine are blamed for thinning the earth's protective layer - which filters harmful ultraviolet radiation that can cause skin cancer and cataracts.
They were banned 20 years ago under the Vienna Convention and its Montreal Protocol of 1987.
"As the amount of chlorine and bromine will continue to decline over the next decades, but very slowly, one expects the ozone hole to get smaller and smaller," Mr Braathen said.
But uncertainties remained regarding the pace of the ozone's recovery, according to the Norwegian expert.
"At the same time there is this issue of climate change which will lead to higher temperature on the ground - the globe is warming up - but in the stratosphere temperatures will decrease."
That will encourage more ozone loss in the Arctic and the Antarctic, he said.
