Ozone pact: obsolete before it starts? Ozone layer may be decaying faster than pact can protect it

On New Year's Day, the international treaty to save Earth's protective ozone layer goes into effect. But critics already consider its provisions obsolete. The United States Environmental Protection Agency, for example, estimates that the restrictions on production of chlorofluorocarbons (CFCs) won't achieve the treaty's goal in limiting the stratospheric buildup of ozone-destroying chlorine. Furthermore, there are indications that the global ozone layer may be decaying faster than expected when the treaty was negotiated in 1987.

Critics also believe that the fact that few developing nations have signed and ratified the treaty is a major weakness. Even those that do sign have less restriction on CFC production than do developed countries. Uncertainty about future CFC production in developing nations was a principal reason that the congressional Office of Technology Assessment in the US considered the treaty's goal of halving global CFC production by 1998 to be optimistic.

Thus the first significant action interested nations will take under the treaty will be to review it with an eye to tightening CFC restrictions and bringing more developing nations under its provisions. The first opportunity to do this will be the world conference on protecting the ozone layer to be held in Britain in March. Then, in April, Finland will host the first of the regular review meetings specified by the treaty.

The Montreal Protocol on Substances that Deplete the Ozone Layer - to use the treaty's formal name - will freeze CFC production in ratifying developed countries at 1986 levels beginning July 1. It then will cut that production in half by 1998. There is a 10-year grace period beyond that for developing nations.

When 45 nations endorsed the protocol in 1987, its framers expected these restrictions to limit the rise in stratospheric chlorine concentration (from CFCs) - now about 2.7 parts per billion (ppb) - to roughly 5 ppb. The EPA released a study last September that estimates the concentration is likely to reach 8 ppb.

Moreover, in March, the US National Aeronautics and Space Administration (NASA) released a study showing that, on a global average, the stratospheric ozone layer has thinned by about 2.5 percent over the past decade. Thus the famous springtime Antarctic ozone hole is no longer the main indication of loss of this stratospheric shield that absorbs harmful ultraviolet radiation from incoming sunshine.

Earlier this month, Robert T. Watson, who chaired NASA's Ozone Trends Panel, told a scientific meeting in London that analyzing data in terms of specific regions and seasons rather than as annual global averages gives an even more startling picture of Northern Hemisphere winter ozone layer declines. He reported that, between 1969 and 1986, stratospheric ozone concentrations dropped some 6 percent between north latitudes 53 and 64 degrees and almost 5 percent between latitudes 40 and 52 degrees. There also were hints of small loss between north latitudes 30 and 39 degrees.

Cynthia Pollock Shea, environmental analyst at Worldwatch Institute in Washington, says studies such as these ``show that more [ozone layer] depletion has already occurred than negotiators assumed would happen in 100 years.'' She adds that this increases the need to control more chemicals than just CFCs. Some chemicals not regulated by the treaty - especially methyl chloroform and carbon tetrachloride - ``are also major threats to the ozone layer,'' she says.

Some 45 nations endorsed the Montreal Protocol in 1987. Of these, only about two dozen, mainly industrialized nations, have signed and ratified the treaty - enough to bring the treaty into force Jan. 1. The ratifying countries represent over two-thirds of present global CFC production.

It is already clear that the treaty's restrictions probably won't provide as much ozone-layer protection as treaty framers had hoped. And even that degree of protection would be compromised if developing countries step up their production and use of CFCs, which are still widely used as spray-can gas and presently are essential as working fluids in air conditioners and refrigerators.