Whatever Happened to Global Cooling?

Global warming skeptics often cite contradictory reports from a generation ago warning of global cooling. In 1975 Newsweek wrote of "ominous signs" that temperatures were dipping, and a year later National Geographic suggested the possibility of a worldwide chilling trend. Stephen Schneider, a climatologist at Stanford University, recalls those stories well. "I was one of the ones who talked about global cooling," he says. "I was also the one who said what was wrong with that idea within three years." Schneider coauthored a 1971 article in the journal Science about atmospheric aerosols—floating particles of soil dust, volcanic ash, and human-made pollutants. His research suggested that industrial aerosols could block sunlight and reduce global temperatures enough to overcome the effects of greenhouse gases, possibly triggering an ice age. But he soon realized that he had overestimated the amount of aerosols in the air and underestimated the role of greenhouse gases. "Back ...