February 28, 2007
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A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 8, NUMBER 6, JUNE 1995
NORTHERN OZONE LOSS
Europe and U.S.
researchers observed record-breaking Arctic ozone depletion over the past winter
and early spring, and substantial depletion over high northern midlatitudes
outside the Arctic region.
Arctic depletion reached 50 percent in some thin layers, but typically ran
30-40 percent over extended areas. The losses are attributed to the combination
of unusually low temperatures in March, which in the presence of sunlight drive
chemical reactions between ozone and anthropogenic chlorine compounds. According
to Neil Harris of the European Ozone Research Coordinating Unit in Cambridge,
U.K., ice cloud particles, which provide a site for the reactions to occur, are
becoming more common in the Arctic stratosphere. (See New Scientist, p.
7, Apr. 8 1995.) This trend has two causesthe Arctic stratosphere is
becoming colder, and also the amount of water vapor is increasingboth of
which are expected results of greenhouse warming.
In middle and high latitudes of the Northern Hemisphere outside the Arctic,
ozone levels during the 1994-1995 winter were 10-20 percent lower, and in some
areas up to 35 percent lower than values observed around 1980, before efforts to
address ozone depletion began, according to the U.S. National Oceanic and
Atmospheric Administration (NOAA). In contrast to the situation in the Arctic,
however, scientists are not sure to what extent air circulation in the
stratosphere accounts for the depletion, compared to any effect of chemical
destruction. NOAA's Northern Hemisphere Winter Summary: 1994-95 is
available from Alvin Miller at the NOAA Climate Prediction Center in Washington,
D.C. (tel: 301 763 8071; fax: 301 763 8125). (Printed copies are limited;
request information on electronic availability.)
See Nature, p. 487, Apr. 6; Chem. Eng. News, pp. 8-9, Apr.
10; Global Environ. Change Rep., pp. 4-5, Apr. 14; Science News,
p. 277, May 6.
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