ONE of the recurring environmental nightmares envisions coastal cities sinking beneath the sea as the climate warms up and icecaps melt. The warm-up would be due partly to the accumulation in the atmosphere of heat-trapping carbon dioxide (CO2) gas, which is released as coal and other fossil fuels are burned. But climatologists generally concede that no one has a good enough grasp of the subject to say with any certainty when, where, and to what extent this nightmare might begin to materialize. Nevertheless, scientists from 29 nations who met recently in Villach, Austria, are urging governments to ignore the uncertainties and begin to shape decisions on energy supply and land-use policy, on the assumption that inundation may soon be upon us.
Conference participants warned that the rise in sea level may well become important early in the 21st century. That's sooner than previous estimates had tentatively forecast. This warning was issued despite the fact that no scientist can make such a prediction today with any certitude.
Once again, a potential but uncertain environmental threat is being cited as reason for far-reaching political action. Some CO2 researchers have been advocating this kind of action for a number of years. They would have nations begin restricting use of fossil fuels now to cut down on CO2 emissions. They would have irrigation projects, water supply planning, and coastal development shaped on the assumption that climatic warm-up will both raise sea levels and change precipitation patterns.
The Villach statement repeats this plea. It appears to be saying that fear of an uncertain environmental danger should inform government policy when sound scientific guidance is not yet available. This is a poor basis for official action.
How can governments factor climatic change into these important economic decisions when the scientists themselves cannot say with any certainty what those changes will be or how they will affect a given locale? It is virtually impossible for policymakers to act on such vague warnings.
The scientists concerned, however, must have been aware of this problem and did not make their plea lightly. The meeting was sponsored by the United Nations Environment Program, the World Meteorological Organization, and the International Council of Scientific Unions. This authoritative gathering gave its warning with the conviction that it is dangerous to delay curbing the CO2 buildup, even though its threat is still ill defined.
When so many competent scientists share such a conviction, their concerns deserve respect, even though the policy action they urge may seem impractical. Moreover, there is one aspect of their plea which should lead to action now. This is the need to pursue research on climate change with a sense of urgency.
Climatic warm-up is a very complex prospect to evaluate scientifically. More than CO2 is involved. Climatologists now recognize that other gases accumulating in the atmosphere have at least as great a warming influence as CO2 -- perhaps greater. These gases include naturally generated methane from cattle, swamps, and other sources; chlorofluorocarbons, such as those used in spray-can propellants; and oxides of nitrogen from fertiliizer. Thus, even were the rise of CO2 to be curbed, the warm-up could, to
some extent, continue.
The difficulty of forecasting the effect of this mix of heat-trapping gases is illustrated in a recent report from a United States Department of Energy workshop held in September 1984 which considered icecap melting and sea-level change.
The report explains that the present climatic trend is so poorly understood that no one knows whether or not the polar icecaps are shrinking and consequently swelling the ocean today. Indeed, what evidence there is suggests the Antarctic ice is actually growing, and taking water out of the sea. The report also explains that, with present trends so poorly known and the art of simulating climate change on computers still in a rudimentary stage, forecasts of what will happen in the next centur y range from no significant change in sea level to rises of several feet.
The workshop participants were quite specific, however, in laying out the research that would clarify present climatic trends and sharpen scientists' ability to assess the warm-up threat. The Villach conference is equally specific.
Here, then, is an area where governments can -- and should -- act now. The threat of climatic warm-up may still be too vague for them to reorder energy and land-use priorities. But it is credible enough for them to organize a fast-paced global research effort to reduce the scientific uncertainties to the point where responsible policy decisions can be made.
A Tuesday column. Robert C. Cowen is the Monitor's natural science editor.