Last December representatives of 160 nations gathered in Kyoto, Japan, to hammer out an agreement on emissions of greenhouse gases. But before the U.S. Senate ratifies the Kyoto treaty, it’s important to point out that much discussion of the “greenhouse effect” is little more than hot air.

The Kyoto agreement rests on forecasts of future greenhouse gas emissions. But energy use, which requires the burning of fossil fuels, depends on economic growth and prosperity. Economists aren’t soothsayers: they often over- or underestimate growth, and they can’t be expected to discern how technological advances will change fossil fuel consumption.

Indeed, many climate models — which remain unreliable — predict that most of the climate change will occur many decades from now — the forecasted increase of 4.5 degrees Fahrenheit won’t happen for a century. It’s impossible to have any confidence in forecasts of the technology, population or energy sources of 2098. We can predict, however, that future generations will have better technology at their disposal, that they will be wealthier, and that they will live longer. They will certainly be in a better position to deal with adverse climate changes than we are today.

The Clinton administration had difficulty deciding what it could accept at Kyoto. Its quandary was magnified by the projected failure of the United States to reduce emissions to 1990 levels by the year 2000. Rather than cutting them, a booming economy appears likely to boost emissions of carbon dioxide by at least 15 percent in this decade. Cutting emissions enough to prevent climate change, which might require slashing emissions by some 60 percent, seems out of reach. Avoiding a warmer world would require a radical curbing of emissions by all countries, which in turn would lead to a worldwide slowdown in growth, perhaps even a depression that might make the 1930s look like Disneyland on a good day.

The Kyoto agreement is futile. Even Bert Bolin, the former chairman of the United Nations’ body of experts on global warming, says that the present plan would, if fully implemented, cut warming a quarter century from now “by less than 0.1 degree C, which would not be detectable.” We are plunging into a treaty that creates gigantic obligations without examining its costs and benefits. Congress has demanded that the Clinton administration provide estimates of the costs, but none have been forthcoming.

For most of the world, warming over the next century would cost only a little or would be an actual benefit. The few regions that actually would be harmed by warming should have help.

There is no need to rush into a treaty that would have little benefit but great cost. If climate change becomes a real problem, many steps can be taken that wouldn’t cripple our economy. Ocean scientists have shown, for example, that if the seas were “fertilized” with iron filings, phytoplankton (algae) would bloom and absorb vast quantities of carbon dioxide. The minuscule plants are nutritionally starved for iron and, when provided with that metal, multiply rapidly, absorbing large amounts of carbon. Some experts estimate that iron supplements might offset 15 to 20 percent of man-made carbon dioxide over the next few decades.

In addition, harvesting and replanting timber could sequester much carbon. Forest researchers have concluded that an active program of cropping and replanting fast-growing forests, then turning the lumber into housing and other long-term products, together with reforestation, could offset 12 to 15 percent of human greenhouse gas emissions. Seeding the ocean with iron and properly managing forests could by themselves do as much to slow climate change as capping greenhouse gas emissions at 1990 levels. Furthermore, scientists may develop other strategies in the future that don’t require shrinking our economy.

The administration is under tremendous pressure to act immediately. To retain credibility with environmentalists, politicians, other countries and the mass media, it must take steps to reduce carbon dioxide emissions even if the limitations would have no benefit and would potentially impose high costs. To succeed in this high-wire act, President Clinton will probably propose new regulatory steps and mandates, such as higher fuel efficiency standards for new cars, more stringent restrictions on appliances, strict insulation levels for new buildings and more spending on mass transportation. Most of those regulations would be phased in slowly — that is, after President Clinton leaves the White House and many current members of Congress retire. The actual legislation required to meet the goal might even await a future Congress. Whatever difficulties present themselves, the administration will negotiate a formula that will allow it to claim that the entire world is cutting greenhouse emissions.

In short, this unnecessary measure would devastate our economy. For most of the world, warming over the next century would cost only a little or would be an actual benefit. The few regions that actually would be harmed by warming should have help. Delaying action by 20 to 30 years is the only prudent, “no regrets” policy. Technology will advance. Incomes in Third World countries will grow. The world will be more capable of coping with change. Except for measures that make sense with or without global warming — like ending subsidies for energy and energy use — Congress should resist any attempts to limit greenhouse gas emissions.