The president and the Congress have presented the nation with the exciting prospect of solving the energy problem by building plants that will convert our abundant coal resources into more readily usable fuel, such as oil or "natural gas." In an almost crisis atmosphere of the moment, the true environmental and economic costs of synthetic fuels he been overlooked in the apparent desire to provide an easy answer to a complicated problem.

The most important environmental issue associated with a major commitment to synthetic fuel is the possible worldwide change in climate rsulting from the loading of the atmosphere with carbon dioxide. This gas, present in minute amounts, absorbs heat that would otherwise radiate from the earth out into space. Carbon dioxide acts as a blanket keeping the earth warm. Increasing the carbon dioxide content of the atmosphere will increase the number of blankets and raise the temperature of the earth.

These changes in temperature could bring about significant worldwide changes in the way people live. The changes are today poorly understood -- but could have far-reaching implications for human welfare in an ever more crowded world, would threaten food supplies and present a further set of intractable problems to organized societies.

When will the carbon dioxide content of the atmosphere increase to levels where the effects become noticable? The answer depends on how fast the world increases the use of carbon-based fuels, natural gas, oil and coal, and on whether or not synthetic fuels become an important element in the world fuel economy. To make synthetic fuels, energy must be used. That use of energy produces carbon dioxide, as does the burning of the synthetic product. The net result is that synthetic fuels produce two to three times more carbon dioxide than do the natural fuels.

If the world continues along the lines of the past 30 years, and if the current mix of gas, oil and coal is maintained, then the carbon dioxide content of the atmosphere will double in about 50 years. If, on the other hand, the world shifts to coal and synthetics, then the doubling will come in about 30 years. The 20-year acceleration may not seem large, but it could eliminate the time needed to develop the alternative fuel of the future -- solar, fusion or nuclear.

The basic policy question associated with the climatic impact is that we may not be absolutely certain that the earth is warming up until 1990 or 1995. By that time, if synthetic-fuels investment and infrastructure are in place, it will be extraordinary costly in economic and social terms to move away from a synthetic-fuel economy. Once hooked, the cure for synthetic-fuel addiction would be very costly.

The enregy challenge is obviously worldwide and cannot be resolved by one nation acting alone. The communique from the Tokyo summit made it clear that the Western nations recognized the longer-term economic and environmental issues of using carbon-based fuels. However, the United States provides leadership on many international issues. The elements of policy I propose here are for the United States, but they apply as well to the world:

1Acknowledgement of the problem: The Co2 problem is one of the most contemporary environmental problems, is a direct product of industrialization, of climates worldwide and therefore the stability of all nations, and can be controlled by controlling fuel policies. No technical means of controlling carbon dioxide exists today. Steps toward control are necessary now and should be part of the national policy in management of resources of energy.

2.Conservation of carbon-based fuels : The element of any policy that offers the hope of being effective is conservation. Limitation of the rate of exploitation of fuels is possible. The rate is controlled currently by price, taxation and regulation. It can be controlled as a matter of policy. All actions of government should be reviewed to determined effects of the total use of carbon-based fuels.

3.The choice of carbon-based fuels and the use made of them bears heavily on the amount of Co2 released to produce a unit of energy. Natural gas is by far the best carbon-based fuel for limiting carbon-dioxide production.

The proposals for a massive synthetic-fuels program arise from the misconception that the United States is running out of natural carbon-based fuels. That assumption is wrong. For example, over the past few years I have studied the probable reserves of natural gas. I am convinced from my work and that of my colleagues that, in the continental United States, there exist vast resources of natural gas in both shallow and deep basins that have not been exploited. The lack of exploitation flows from the fact that historically, in terms of constant dollars, the energy content of natural gas has been underpriced by 10 to 30 percent with respect to domestic oil and 200 percent with respect to imported oil. As a result, there has been little economic incentive to develop this resource, which in burning produces less carbon dioxide than any of the other carbon-based fuels. In the longer term, solar, fusion and nuclear power may provide alternative options that are both environmentally and economically compatible.

My idea is that before we commit ourselves to the construction of a major synthetic-fuels infrastructure involving the investment of billions of dollars, we should make every efforrt to understand not only the short term benefits and the costs, but also the longer-term consequences to the generation that must live with the decisions taken today. . CAPTION: Illustration, no caption, By Geoffrey Moss for The Washington Post