Greenbacks for the Greenhouse?

Optimistic estimates place it at around 17 percent of U.S. GNP. Most pessimistic forecasts say it could cost nearly five times that much.

The scientific jury is still out on the dangers posed by global warming. The New York Times reports that fewer than 300 climatologists and environmental scientists have conducted research on the greenhouse effect; only a handful of them are concerned enough to recommend actions to slow global warming. But they all concede one thing: The cost of slowing the man-made accumulation of greenhouse gases could be staggering. (See "Learning to Live with the Greenhouse Effect," Jan.)

Pessimistic climatologists claim that to prevent further climatic disruptions, carbon dioxide emissions would have to fall 20 percent by the year 2100. Alan S. Manne of Stanford University and Richard G. Richels of the Electric Power Research Institute estimate the global costs of these reductions to be anywhere from $800 billion to $3.6 trillion. The Times reports that a forthcoming Congressional Budget Office report will place the cost of simply stabilizing greenhouse gas production in the United States at nearly 2% of GNP annually by the middle of the next century.

Thomas Schelling, an economist at Harvard's Kennedy School of Government, believes that in the United States, "the first 10 to 15 percent of carbon emission reductions wouldn't cost much. It would get pretty costly after that." The early reductions might come from improving automotive gasoline mileage, adding insulation to homes and offices, and increasing refrigeration efficiency or ending the use of chlorofluorocarbons (CFCs).

Skeptics counter that these proposals would be much more expensive. Smaller, fuel-efficient cars are less crashworthy and would cause more traffic deaths; and if global warming is for real, until a substitute for CFCs emerges, there will be more, not less, pressure to use CFCs for air conditioning and refrigeration.

Additionally, other nations may not be likely to reduce fossil fuel usage. Western European already drive fuel-efficient cars, and some East Bloc citizens already can't heat their homes above 40 degrees. And developing countries, especially those with healthy supplies of fossil fuels, are resistant to draconian environmental policies that would limit their economic growth. Greenhouse skeptics warn that we should not unilaterally adopt policies that penalize the United States while other nations ignore them.

Skeptics, and even some believers, also caution against using computer models to dictate policy. Models can't anticipate technological advances, and these changes could make government actions superfluous. Inventors are developing motor vehicles powered by everything from rechargeable batteries to vegetable oil. Schelling suggests that breakthroughs in nuclear power generation could lead to clean nuclear plants that would replace fossil fuel-powered electric generators, further reducing carbon emissions.

Except for a small group of alarmists, all the global warming watchers offer a similar message: Before getting too upset about global warming, remember that there are more immediate concerns. Schelling says, "If I were advising Mikhail Gorbachev, I would tell him: Forget the greenhouse effect. Get your economy working first."