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- GENEVA (Reuters) - Satellite
data from above Antarctica show an unusually early and severe drop in the
level of ozone, the World Meteorological Organization said on Tuesday.
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- The United Nations agency said an average drop of 30
percent was recorded compared to the benchmark 1964-76 period, before a
hole in the protective ozone layer was reported.
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- But it said meteorological conditions in the stratosphere
could change and it was too soon to say if there would be record depletion
of the layer this year.
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- The ozone protects people, animals, and crops from the
sun's dangerous ultraviolet rays.
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- Chlorofluorocarbons (CFCs) and other ozone-destroying
chemicals have been banned since 1996, but scientists say it will be decades
before the ozone layer recovers.
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- Ozone depletion normally begins in late August, intensifying
until it peaks in October, and eventually recovers in November or early
December.
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- ``The latest satellite observations in the sunlit portion
of the Antarctica perimeter show an average decrease of about 30 percent
in the total amount of ozone overhead when compared to the 1964-76 norms,''
WMO said in a statement.
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- ``This is double the 15 percent reported two weeks ago
and unusual for this early period.
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- ``The sunlit region surrounding Antarctica continues
to have considerably less ozone than normal and has been demonstrated with
both ground-based and satellite measurements,'' it added.
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- Substantial Decreases
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- Preliminary ground-based measurements taken between August
16-22 from four Antarctic stations all showed ``substantial decreases''
when compared to the period before the ozone hole appeared.
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- France's Dumont d'Urville reported levels 20 percent
below, Russia's Mirny reported 35 percent below, Japan's Syowa and Ukraine's
Vernadsky reported 25 percent below, it said.
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- ``Both Syowa and Vernadsky have ozone records extending
back more than 25 years that indicate the Syowa weekly average is the second
lowest on record while for Vernadsky this year is the lowest,'' the statement
said.
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- ``However, prevailing meteorological conditions in the
stratosphere, particularly during the Austral Spring, strongly influence
the extent and intensity of ozone loss and may substantially reduce the
total seasonal depletion.''
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- Michael Proffitt, WMO's senior scientific officer and
ozone expert, told Reuters: ``These conditions are a bit unusual, they
are strong initial conditions. It is a strong start.
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- ``Any year could be a record year... We are watching
carefully and will have a much better idea in two weeks,'' the American
expert added.
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- Sunlight should reach the South Pole around September
21-22, enabling scientists to make further measurements, according to Proffitt.
``We expect to see significant loss as it becomes uncovered,'' he said.
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- Ground-based measurements first detected the ozone hole
over Antarctica in about 1985, according to Proffitt, who took part in
a NASA project two years later which flew experts in and out of the hole
as it developed.
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- ``Things can change. The wonderful thing about nature
is we can get meteorological conditions that can change the picture,''
he said.
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