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25 years on

Posted 17/09/2012 by sevans

Twenty-five years ago, in 1987, the Montreal Protocol was signed as the first major global treaty to reduce the environmental impact of chemicals. Ultimately designed in response to the discovery by US scientists Sherwood Rowland and Mario Molina, at the University of California Irvine, of a mechanism by which chlorofluorcarbons (CFCs) were implicated in depletion of the Earth’s ozone layer, the protocol has been praised as an example of international cooperation on an environmental issue. It has been held up as an example that the international community should follow in its handling of climate change, which has not been quite so successful.

But has the protocol really been effective? The general opinion is that it has stopped the decline but due to the long atmospheric lifetimes of the CFCs used as propellants in aerosol spray cans and as refrigerants, it will take much longer timescales measured in decades for the amounts to reduce to levels recorded before the so-called ozone hole was first identified in 1984. But there are certainly signs that the protocol has had an effect.

‘The temperature conditions and the extent of polar stratospheric clouds so far this year indicate that the degree of ozone loss will be smaller than in 2011, but somewhat larger than in 2010,’ according to the UN weather agency. The agency also added, however, that the ozone hole will be smaller than the record size reported in 2006.

Observers generally consider that without the Montreal Protocol, then ozone depletion could have reached 50% over the Antarctic, but more recently there have been suggestions that ozone depletion would have also occurred elsewhere across the globe, particularly in the mid-latitudes where a decrease in ozone of around 5% has been suggested.

This decrease is said to have resulted in an increase in UVB radiation reaching the ground of around 5% in regions with high population levels. Although this is a relatively small increase, UVB radiation has been implicated in skin cancer. Concerns about the human health impact of the Antarctic ozone hole spurred on Australia’s Slip-Slop-Slap campaign: slip on a shirt, slop on sunscreen and slap on a hat, which had actually been launched in 1981 as a result of rising numbers of cases of skin cancer, before concrete evidence of ozone depletion had been presented.

The Australian campaign spawned similar campaigns around the world but they have generally been attributed to the impact of the evidence about the ozone hole over the Antarctic.

The Montreal Protocol showed that it was possible for the global community to act in unison, but subsequent environmental challenges have shown it to be the exception rather than the rule. Whether this is a result of global politics or the lack of hard evidence that affects individuals at a personal level is a point that probably can be argued without any real conclusion. 

But this should not detract from the success of what at the time was a major challenge. The Montreal Protocol set out with a clear vision of what was to be achieved, and 25 years on the evidence is showing that it has indeed been successful.

Neil Eisberg - Editor

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