Is The Earth Warming Up?

The Great Plains has become a dust bowl, and people are moving north into Canada's uplands to seek work. Even in Alaska, changing ocean currents are boosting the fish catch. New York is sweltering in 95 degrees weather that began in June and will continue through Labor Day. In the Southeast the hot spell started six weeks earlier . . .

That picture of the future is all too familiar to many meteorologists. To some, it makes the drought that is crippling the nation's midsection seem an ominous harbinger of things to come. Because of the greenhouse effect, a process by...