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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 2, NUMBER 11, NOVEMBER 1989

NEWS...
ANOTHER SEVERE OZONE HOLE

Item #d89nov1

Contrary to the expectation of many scientists, stratospheric ozone over the Antarctic declined in September and October 1989 to levels as low as those measured in the record low year of 1987. Measurements made at New Zealand's Scott Base in Antarctica and by the NIMBUS-7 satellite indicate that total ozone decreased by about 45 percent between early August and October 5. As in 1987, stable conditions in the midlatitude Southern Hemisphere stratosphere permitted an extremely cold polar vortex to develop; the cold temperatures are thought to be necessary for severe ozone depletion by chlorine compounds through the formation of polar stratospheric clouds. Most atmospheric scientists expected wind patterns to develop in the late Antarctic winter that would disrupt the vortex, but this did not happen. (See New Scientist, p. 27, Oct. 7, 1989; Science News, p. 246, Oct. 14; Science, p. 324, Oct. 20.)