Courtesy the NASA Earth Observatory. NASA graph by Robert Simmon, based on data provided by the NOAA Climate Monitoring and Diagnostics Laboratory.
If the scientific story of global warming has one great hero, he is James Hansen, and not only because he is the most important climatologist of his era, whose massive computer models were demonstrating by the early 1980s that increased CO2 posed a dire threat. Hansen—who has spent (despite attempts by several administrations to fire or muzzle him) almost his entire professional career at NASA as head of the Goddard Institute for Space Studies—is equally important because he’s been willing to state publicly, and in plain language, the threat we face. At no point was this candor more crucial than in June of 1988. Earlier congressional hearings on climate change had yielded scant coverage, but by June 23 it was already clear that 1988 would be a very hot summer—water levels along the Mississippi eventually fell so far that barge traffic was halted; crop yields dropped sharply; and forest fires broke out across the West. Hansen said in his testimony that while no particular event could be directly attributed to climate change, he and his team could say with “99 percent confidence” that humans were heating the planet. Later, in a scrum of reporters outside the hearing room, he added that it was time to “stop waffling, and say that the evidence is pretty strong that the greenhouse effect is here.” The story ran above the fold on the front page of the New York Times the next day, and although some scientists were irked by Hansen’s outspokenness, funding suddenly jumped for work on global climate change. Hansen’s testimony had ignited the most intense period of scientific investigation of any topic ever.