The long, hot summer in the Eastern United States and the drought in the Middle West have awakened concerns that the global climate may be permanently changing. Some suggest "the greenhouse effect," caused by carbon dioxide in the atmosphere, may already be here. If so, it is doubtful that governments are ready to deal with the resulting problems.Spurred by environmentalists and concerned governments, some international action has already been taken.

In 1987, 34 nations, including the U.S., meeting in Montreal, signed a protocol calling for the reduction from 35 to 50 percent in the emissions of an offending class of substances, chlorofluorocarbons, by the end of the century.

The depletion of tropical forests represents another threat, both to a vital resource and to the forests' beneficial effects on the global climate.

In 1986, 42 nations, including both rain forest countries and the principal users of the hardwoods, organized the International Tropic Timber Organization to discuss ways to reduce the loss of the forests, now estimated at 30 million acres a year.

In January, agreement to cooperate on the protection of the ozone was incorporated in a U.S.-Soviet scientific cooperation agreement. In June, the U.S. and the Soviet Union were among nations represented at a conference in Toronto called to seek ways to reduce fossil-fuel use.

Such meetings, however, represent only tentative steps toward the resolution of what could ultimately be a catastrophic world problem.

The issues decisionmakers and diplomats must consider in facing a deterioration in the global climate are complex, forbidding, and urgent.

- The causes lie in actions by millions of individuals around the world that they see as vital to their health and welfare, unlike traditional questions of war and peace that rest with decisions of individual governments and their leaders.

- The issues are inherently domestic and will result in conflicts between governments seeking to cooperate on a global scale and internal private interests.

- The potential costs of corrective measures could be enormous. A New York Times article commented that "some economists are predicting that it will eventually cost tens if not hundreds of billions of dollars a year to cut down the gaseous emissions . . . raising the surface temperature of the planet."

- The alternatives to fossil fuels are themselves controversial. The most obvious alternative is nuclear power, but in the post-Chernobyl period, many communities, especially in the U.S., strongly oppose an extension of nuclear power.

- The internal decision-making will involve more actors than traditional foreign policymaking. Bureaucratic leadership is likely to fall to those competent in the technical aspects, but less prepared to deal with the international relations involved.

- Finally, the ability of governments to deal with the issues will be complicated because scientists do not yet agree on the degree of danger.

Much that has been written on the greenhouse effect suggests that, whether or not the current climatic conditions in the U.S. represent its arrival, the future threats to the global environment are real.

The argument over or not whether "greenhouse" has arrived becomes irrelevant. Governments and diplomats should prepare now to deal with this new foreign affairs agenda.

(David D. Newsom is associate dean and director of the Institute for the Study of Diplomacy at Georgetown University.)