THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: Tuesday, December 20, 1994 TAG: 9412200338
SECTION: FRONT PAGE: A2 EDITION: FINAL
SOURCE: COX NEWS SERVICE
DATELINE: WASHINGTON LENGTH: Medium: 54 lines
New satellite data provides conclusive evidence that annual ozone holes over the South Pole are caused by chlorine from manmade chemicals, not from naturally occurring sources, National Aeronautics and Space Administration scientists said Monday.
``This nails it. There is no other possibility,'' said Anne Douglass, deputy project scientist of NASA's Upper Atmosphere Research Satellite program.
Measurements made by a device developed at NASA Langley Research Center in Hampton confirmed the finding. Langley's Halogen Occultation Experiment (HALOE) detected the presence in the Earth's stratosphere of fluorine gases, a primary constituent of the ozone-destroying chemicals.
In the stratosphere, ozone blocks ultraviolet rays from sunlight - a major cause of skin cancer - but global levels of ozone have declined gradually for over a decade. That trend is annually punctuated by the dramatic appearance of an enormous ``ozone hole'' over Antarctica.
Virtually all of the ozone in the stratosphere over a growing area of Antarctica is destroyed in a few days each fall. After several weeks, changes in weather patterns cause ozone from surrounding areas to flow in and replenish the ozone holes, scientists say.
Previous measurements have convinced most scientists that the ozone destruction is caused by chain chemical reactions involving chlorine.
But the source of the culprit chlorine has remained somewhat controversial.
Ever since a treaty was ratified in 1987 to gradually eliminate worldwide production of chlorofluorocarbons, or ``CFCs,'' the chemicals believed responsible for destruction of the Earth's ozone layer, some scientists and political conservatives have argued that chlorine in the stratosphere may come from volcanoes.
Talk show host Rush Limbaugh, whose radio program is heard by millions of listeners, has charged that talk of ozone depletion by CFCs is a ``hoax.''
Douglass, Mark Schoeberl and other NASA scientists said data collected by the satellite convinces them that approximately five-sixths of the ozone-destroying chlorine in the stratosphere comes from CFCs.
The conclusive finding, they said, was the presence of fluorine, the ``fluoro'' part of the CFC molecule, in amounts that correspond to chlorine in the stratosphere.
``There is no natural source of fluorine,'' said Schoeberl.
The Upper Atmosphere Research Satellite is a part of NASA's ``Mission to Planet Earth'' program. by CNB