CSIRO scientists have discovered a new ozone-destroying chemical in the atmosphere, as positive signs emerge that damage to the ozone layer should decline in the next decade.
Halon-1202, which has an ozone depletion potential approximately half that of the common CFCs, has increased five-fold in the atmosphere since the late 1970s.
During the past two years the atmospheric concentration of halon-1202 has been growing at 17 per cent per year.
Unlike other halons used in the past for firefighting, halon-1202 is not controlled by the Montreal Protocol. The source of the new halon is a mystery, adding to scientists' concerns over its potential impact on the ozone layer.
"The rapid growth of halon-1202 comes as a surprise to us," says Dr Paul Fraser from CSIRO Atmospheric Research.
Dr Fraser speculates that gas may be by-product of inefficient production of other halons in developing countries. Alternatively, he says, some countries might be manufacturing halon-1202 for military applications.
Under the Montreal Protocol, developing countries have until 2010 before they must completely phase out halon production. China, the Republic of Korea, India and Russia are the only countries known to still be producing halon.
Continuing growth of halons in the atmosphere is in stark contrast to what is happening with CFCs.
"Our measurements show that most CFCs are either slowing down their atmospheric growth rate, have stabilised in the atmosphere or are actually dropping in concentration," says Dr Fraser.
"The international community will have to consider extending the ban on production of halons to halon-1202 if we are to protect the ozone layer," says Dr Fraser.
The Australian Government has recognised the problem of halon-1202. At a recent meeting of Montreal Protocol countries in Geneva, Australia was successful in having the issue referred to the Protocol's Scientific Assessment Panel.
Dr Fraser expects that ozone recovery is likely to be detected in the next 10-20 years. However, continued emissions of halons will delay this recovery.
CSIRO's discovery comes from measurements of pristine air collected at the Bureau of Meteorology's Cape Grim baseline air pollution station in north-western Tasmania. CSIRO's research into ozone depleting chemicals is being done in collaboration with the Co-operative Research Centre for Southern Hemisphere Meteorology.
Anyone who has a halon fire extinguisher should contact the DASCEM Halon Bank on freecall 1800 65 80 84.
A graph showing a rapid rise in the atmosphere of halon-1202 is available on request from the Division. Broadcast quality video footage of Cape Grim is also available on request.
More information from:
Paul Holper 03 9239 4661 (W); 0419 894 427 (mobile)03 9583 9903 (H)[email protected]
Dr Paul Fraser 03 9239 4613 (W)03 9787 2161 (H)[email protected]
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