Half a century ago, in the 1950s, the prevailing view in the scientific community was that only a negligible effect on climate would result from anthropogenic increases in atmospheric carbon dioxide (CO2) concentrations. Svante Arrhenius, working at the end of the nineteenth century, realistically calculated that climate was sensitive to CO2 but thought that doubling atmospheric CO2 might take some 3,000 years.

Fifty years later, most scientists studying the issue had come to incorrect conclusions. Some mistakenly thought that the CO2 infrared absorption bands were already saturated, so that increasing CO2 would not increase absorption. Other scientists found other reasons to dismiss the effect of rising atmospheric CO2 levels, thinking, for example, that water vapor absorption of infrared radiation overwhelmed that of CO2, or that the ocean would speedily take up any additional CO2 that human activities might add to the atmosphere.

Bert Bolin (1925 – 2007) was among the pioneering researchers who shattered this complacency and alerted both the scientific community and the wider world to the imminent prospect of manmade climate change. The New York Times for 28 April 1959, reporting on the annual meeting of the National Academy of Sciences in Washington, D.C., reported that, “Members of the academy were told that within 40 years the amount of carbon dioxide in the air may have increased from 25% to 30% above the level at the time when man began using fuels. The effect on climate allegedly might be radical. The matter was discussed by Dr. Bert Bolin of the University of Stockholm.”

Bolin was not quite 34 years old when he made this 40-year quantitative forecast, which proved to be remarkably accurate. This paper discusses how, half a century ago, pioneering research by Bolin and others overturned the conventional wisdom and ushered in the modern era of the science of anthropogenic climate change.