Ozone omens

Ozone omens EVEN as the un celebrated September 16 as the International Day for Preservation of the Ozone Layer, a report published by the World Metereological Organisation (wmo), considerably dampened the spirits of "save ozone" campaigners revealing that the hole in the stratospheric ozone layer -- which protects the earth from harmful ultraviolet radiation from outer space -- is growing rapidly.

Since the late 1970's, a "hole" has been formed in the ozone layer over Antarctica during the southern hemisphere's spring -- September and October thanks to the presence of chlorofluorocarbons (cfcs) in the stratosphere, say scientists. So, in 1987, the un Montreal Protocol on Substances that Deplete the Ozone Layer was ratified to reduce the global production of ozone depleting substances. In 1992, the Copenhagen Amendments were introduced seeking to ban the production of the most damaging compounds in the industrialised nations by 1996.

But despite efforts, the hole increasing in expanse. "There is no need to panic, because this is exactly what we had expected would happen," assures Piet J Aucamp, co-chairperson, Montreal Protocol Science Assessment Panel, University of Pretoria, South Africa. Twenty million tonnes of cfcs, having a life-span of 60-100 years, have been pumped into the atmosphere since they were first manufactured in the 1940s. Therefore, notwithstanding the present accelerated phase-out process, chlorine and bromine (2 cfc components) levels in the stratosphere will increase for the next 5 years, and peak before this decade's end. The recovery phase will begin after then, with the hole shrinking gradually and disappearing completely by mid 21st century.

"The ozone layer will be whole again, provided all the signatories of the protocol honour their commitment," says Aucamp. He says, "In Europe, Germany and the Scandinavian nations have already achieved 100 per cent phase-out. In my country (South Africa), an 85 per cent cut-back has been recorded."

But, the wmo report points out that the depletion level may surpass the record expanse of 38.616 million sq km it reached in end September, 1994. The situation, reportedly, has not improved. "Every 1 per cent drop in ozone means that roughly 1.3 per cent to 1.5 per cent more ultraviolet radiation penetrates the upper atmosphere," warns Rumen Bojkov, special advisor on ozone, wmo.

This seems to cloud the viability of the Montreal Protocol. "Certainly not," insists Aucamp stressing that without the Protocol, unrestricted use of cfcs and other compounds would have tripled ozone depletion.

And signs of recent improvement have been observed, he notes. Last year, a monitoring aircraft launched over South America, which "tested the air" over the entire region stretching till the South Poles, reveals that the 'slope' of cfc emissions are no longer in the rise but have stabilised at a certain level.