The hole in the ozone layer, the earth's protective shield against
ultraviolet rays, is expected to be smaller this year over the Antarctic
than last, showing how a ban on harmful substances has stopped its
depletion, the United Nations said on Friday.
But the hole is probably larger than in 2010 and a complete recovery is still a long way off.
The
signing of the Montreal Protocol 25 years ago to phase out chemicals
that deplete the ozone layer has helped prevent millions of cases of
skin cancer and eye cataracts as well as harmful effects on the
environment, the U.N. weather agency said.
"The temperature
conditions and the extent of polar stratospheric clouds so far this year
indicate that the degree of ozone loss will be smaller than in 2011 but
probably somewhat larger than in 2010," the World Meteorological
Organization (WMO) said in a statement.
The Antarctic ozone
hole, which currently measures 19 million square kilometers, most likely
would be smaller this year than in the record year of 2006, it said.
The annual occurrence typically reaches its maximum surface area during
late September and maximum depth in early October.
But the
banned chlorofluorocarbons (CFCs), once used in refrigerators and spray
cans, have a long lifetime in the atmosphere and it will take several
decades before their concentrations are back to pre-1980 levels, the WMO
said.
The Montreal protocol has been a "great success", U.N. weather agency expert Geir Braathen told a news briefing.
"This
has prevented a major environmental disaster and globally ozone
depletion has leveled off. We haven't really seen any kind of
unequivocal ozone recovery yet," he said.
"Ozone depletion has stopped, leveled off," Braathen said.
In
the Arctic stratosphere, there was record ozone loss in spring of 2011,
but it has returned to more normal conditions this year, he said.
CRS's
Head of Environment commented ' It's taken a generation for the CFC ban
to take affect, but it shows how the international agreements can make a
difference on global issues. While we wait for more action in carbon,
businesses need to take individual action.
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