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30 September 1998 |
Ref 98/237 |
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During the next few weeks, the 1998 springtime Antarctic ozone hole will reach its peak. This ozone hole has opened up over Antarctica every year since the late 1980s.
The hole's current size is approximately 26 million square kilometres, which is approximately three times the area of Australia, and larger than any previous one over the past 20 years.
Eminent US researcher, Dr Susan Solomon, from the National Oceanic and Atmospheric Administration, will present the latest information on stratospheric ozone depletion as the 1998 Priestley Lecturer. The Priestley Lecture is being held today (Wednesday) at CSIRO Atmospheric Research in Melbourne.
"Unfortunately, it's going to be several decades before we see the end of the Antarctic ozone hole," says Dr Solomon.
Dr Solomon discovered that chemical reactions destroy ozone on surfaces such as the ice crystals within high-altitude 'polar stratospheric clouds' as well as on other atmospheric particles high in the atmosphere.
"We're clearly seeing a major impact on ozone depletion caused by the eruption in 1991 of Mt Pinatubo in the Philippines," says Dr Solomon.
"Just as polar stratospheric clouds, volcanic particles make chlorine from CFCs more effective at ozone destruction,' says Dr Solomon.
"Chemical reactions on the volcanic sulfate particles blasted into the stratosphere by the eruption accelerated ozone depletion due to chlorine over the southern hemisphere by about 3 per cent. It is only now that this extra depletion is disappearing," says Dr Solomon.
The Antarctic ozone hole and the year-round depletion of the Earth's protective ozone layer will continue until levels of ozone-destroying CFCs and halons drop to pre-1970 concentrations, around the middle of the next century.
Already, atmospheric scientists have detected reductions in atmospheric concentrations of a number of ozone depleting chemicals, a positive sign that the Montreal Protocol is working.
The Montreal Protocol is the international agreement designed to protect the ozone layer by phasing out production of CFCs and halons.
A colour satellite image showing the current status of the ozone hole is available on request from the Division.
More information from:
Paul Holper 03 9239 4661 (W)
0419 894 427 (m)
03 9583 9903 (H)
E-mail: paul.holper@dar.csiro.au
*** Media representatives are invited
to attend the 1998 Priestley Lecture, on Wednesday 30 September,
at 2.15 pm, at CSIRO Atmospheric Research, 107-121 Station Street,
Aspendale, VIC.
(Australia's largest scientific research organisation)
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