The Scientist Who Gave a Name to Global Warming

Photographs by Paul Hames/California Dept. of Water Resources/Getty Images; Justin Sullivan/Getty Images
1988 James Hansen, then director of NASA’s Goddard Institute for Space Studies, introduces the idea of “global warming” to the public at a Senate hearing in Washington.

I had testified several times during the 1980s without much effect, the immediately preceding testimony being in late 1987. After that, I met with the staffer who had arranged it and expressed the opinion that “global warming” was never going to get much attention if we kept scheduling the hearings in cold seasons. The next hearing was in the summer. By luck it was exceedingly hot, above 100 degrees in Washington. I came to D.C. the evening before. As usual, I was a little slow and did not finish preparing my oral remarks, because I was listening to a Yankee game. At a meeting on the morning of June 23 at NASA Headquarters, I was feverishly preparing my oral testimony when the chairman of the meeting said, “No respectable scientist would say that human-made climate effects are already occurring and detectable.” That caused me to look up suddenly and say, “I don’t know if he’s respectable or not, but I know a scientist who is about to make that assertion.”

At lunchtime, I left the NASA meeting and took a taxi to the Senate. I immediately realized that the public would misinterpret my testimony as meaning that every year would be warm, so I made up some colored dice to illustrate that I was only saying that the climate dice were now “loaded” because of human-made greenhouse gases. I also realized that the public might think that global warming meant continued and expanding droughts. I decided that I should testify once more to try to make the point that global warming pumps up both extremes of the hydrologic cycle. Evaporation, and therefore precipitation, must increase on average, but the precipitation will tend to come in more extreme events, thus resulting in more extreme floods, the historical “hundred-year floods,” occurring more often than once a century. I testified once more, in 1989, and that got attention when I revealed that my testimony had been altered by the White House Office of Management and Budget. Then I bailed out of public appearances for 15 years.

It was not until after the frustrations of the first term of George W. Bush and Dick Cheney that I decided to speak out publicly. Near the end of 2004, I gave a talk recommending that people vote for John Kerry. Then I gave an improved version of the talk at the American Geophysical Union in 2005, which resulted in attempts to censor my speaking. That was when I explained to 60 Minutes that I did not want my grandchildren to say, “Opa understood what was happening but didn’t make it clear.” —As told to Brad Wieners

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