Global warming may be nearly over.

• Position: Climate - Unorthodox reading of the greenhouse effect - Brief Article

Global warming is a natural geological process that could begin to reverse itself within 10 to 20 years, predicts Robert Essenhigh, E.G. Bailey Professor of Energy Conservation, Ohio State University, Columbus. He suggests that atmospheric carbon dioxide--often thought of as a key greenhouse gas--is not the cause of global warming. The opposite is most likely to be true, he says. It is the rising global temperatures that are naturally increasing the levels of C[O.sub.2], not the other way around.

Many people blame global warming on carbon dioxide sent into the atmosphere from burning fossil fuels in manmade devices such as automobiles and power plants. Essenhigh believes these people fail to account for the much-greater amount of C[O.sub.2], that enters--and leaves--the atmosphere as part of the natural cycle of water exchange from, and back into, the sea and vegetation.

"Many scientists who have tried to mathematically determine the relationship between carbon dioxide and global temperature would appear to have vastly underestimated the significance of water in the atmosphere as a radiation-absorbing gas," he argues. "If you ignore the water, you're going to get the wrong answer."

How could so many scientists miss out on this critical bit of information? Essenhigh maintains that a National Academy of Sciences report on C[O.sub.2] levels that was published in 1977 omitted information about water as a gas and identified it only as vapor--meaning condensed water or cloud--which is at a much lower concentration in the atmosphere, and most subsequent investigations into this area evidently have built upon the pattern of that...