April 5, 2000
WASHINGTON (Reuters) -- A long, cold arctic winter spawned one of
the most massive ozone losses on record, but ultimately,
human-made pollution is to blame, scientists from NASA and the
European Union reported Wednesday.
Measurements taken by researchers aboard NASA's high-flying ER-2
plane show ozone in the arctic region decreasing by about 60
percent between January and mid-March. Other data collected by
satellites back this up.
There is no "ozone hole" in the arctic as there sometimes is in
the antarctic, but the arctic ozone depletion reported this year
shows that chlorine compounds contained in some pollution are
lingering in the far north.
Certain chlorine compounds can help destroy the protective ozone
layer in Earth's stratosphere, but only if they are present when
it is extremely cold and a bit sunny, as it was this winter,
according to Paul Newman, a scientist who worked on the ozone
observations.
"We know that there's a lot of chlorine up there from man-made
gases," Newman said in a telephone interview. But he explained
that the chlorine contained in some chlorine-bearing pollutants
remains in a benign form until it connects with extreme cold and
sunlight.
These two conditions are unusual in the arctic winter, he said.
And the production of these pollutants is now limited, so the
amount of chlorine in the stratosphere is not increasing, but
there will be no full recovery of arctic ozone for decades.
"We won't see recovery until 2050 to 2070," Newman said.
Another reason the ozone loss was so severe this winter could be
the lack of weather disturbances on Earth's surface, which tend
to warm the arctic. This lack may have been caused by the warming
greenhouse effect, which tends to weaken such disturbances,
Newman said.
The drop in the ozone over the arctic has caused a slight
depletion of ozone in the northern hemisphere, stretching through
northern Europe and the northern United States, Newman said.
SOURCE: CNN
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