Editor's note: Exactly 20 years ago, on June 23, 1988, James Hansen of the NASA Goddard Institute for Space Studies testified before a Senate committee that he could state with "99 percent confidence" that a recent, persistent rise in global temperature was occurring, and had long been expected. That landmark statement, and the dawn of the global warming discussion, was covered by Andy Revkin, then a DISCOVER senior editor and now an environmental reporter for
The New York Times.
Here we republish Revkin's groundbreaking 1988 article that helped begin to raise awareness of the issue. DISCOVER's science and politics blog, Reality Base, also has an interview with Revkin about what's happened with regard to global warming over the past 20 years.
On June 23 the United States sizzled as thermometers topped 100 degrees in 45 cities from coast to coast: 102 in Sacramento; 103 in Lincoln, Nebraska; 101 in Richmond, Virginia. In the nation's heartland the searing heat was accompanied by a ruinous drought that ravaged crops and prompted talk of a dust bowl to rival that of the 1930s. Heat waves and droughts are nothing new, of course. But on that stifling June day a top atmospheric scientist testifying on Capitol Hill had a disturbing message for his senatorial audience: Get used to it.
This wasn't just a bad year, James Hansen of the NASA Goddard Institute for Space Studies told the Senate committee, or even the start of a bad decade. Rather, he could state with "99 percent confidence" that a recent, persistent rise in global temperature was a climatic signal he and his colleagues had long been expecting. Others were still hedging their bets, arguing there was room for doubt. But Hansen was willing to say what no one had dared say before. "The greenhouse effect," he claimed, "has been detected and is changing our climate now."
