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Ozone: The patient is not getting sicker


Twenty years after the Montreal Protocol came into effect to regulate substances that deplete the ozone layer, the annual ozone hole above Antarctica shows no signs of recovery.

A feature article and editorial in Nature today explain why this is so, and why the Montreal Protocol has been a unique success nonetheless.

As things stand, scientists expect the first signs of recovery of springtime ozone depletion in the polar stratosphere around the year 2065. Outside polar regions, where chemical ozone destruction is less pronounced but potentially harmful to human health, it appears as if ozone levels are beginning to increase.

Globally, the recovery of ozone will occur in a changing atmospheric environment. Greenhouse gases have a cooling effect on the stratosphere, and climate change is likely to also alter atmospheric transport and circulation patterns.

What this means for the ozone layer is not exactly clear. It appears that the changes will in some places delay its recovery, while elsewhere they might lead to a ‘super-recovery’ of ozone.

But not only must models of ozone loss and recovery factor in global warming – abnormally low stratospheric ozone has also a marked effect on climate change here and now. Most strikingly, extreme seasonal ozone depletion over Antarctica seems to explain why the Antarctic Peninsula is warming at an alarming rate while the rest of the continent has actually cooled over the last 30 years.

Quirin Schiermeier

Image: View of the South Pole from NASA’s TOMS (Total Ozone Mapping Spectrometer) satellite. Credit: NASA


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    Brent Hoare said:

    The Montreal Protocol has a lot more to offer than a model for addressing global warming emissions, it is itself an important tool that urgently needs to be strengthened to harvest the ‘low hanging fruit’ of phasing out hydrofluorocarbons (and HCFCs), the high global warming potential ODS alternatives with genuinely climate friendly natural refrigerant solutions.

    The Montreal Protocol may have prevented the atmospheric concentrations of chlorine from getting worse by getting rid of CFCs in developed countries (but the black market will ensure they are readily available in developing countries for years to come unless more is done soon), and because the CFCs are enormously powerful greenhouse gases (5000-11,000 time more powerful than CO2, in round figures) Montreal has done 5 times more to abate emissions than Kyoto will in the first commitment period.

    Nature has made an important contribution to clearing up widespread misunderstanding that the ozone layer problem has been ‘fixed’ by pointing out that ozone recovery will take place in a very different atmosphere from that which existed before the Montreal Protocol.

    However there is every reason for the world to get serious about recovering CFCs, and phasing out the use of high GWP HCFCs and HFCs through strengthening the Montreal Protocol at the next Meeting of the Parties in Egypt in November – to address both ozone and climate issues and the still poorly understood interactions between these indisputably anthropogenic interferences with our planet’s imperilled atmosphere.

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