Guy Callendar was an English engineer, who in the 1930s estimated that man had added about 150,000 million tonnes of CO2 during the past century and the planet had undergone warming on the order of one degree Fahrenheit (0.5 degrees Celsius).

CallendarIn his first published paper, in February 1938, titled “The artificial Production of Carbon Dioxide and its Influence on Temperature”, Callendar showed that there is “a quantitative relation between the natural movement of this gas and the amounts produced by the combustion of fossil fuel”, and argued “that the activities of man could have any influence upon phenomena of so vast a scale… that is not only possible, but is actually occurring at the present time.”

He also referred to the oceans as a “giant regulator of carbon dioxide” which had exceeded the limits of the natural carbon cycle and would not be able to absorb all or most of its excess. But as Arrhenius before him, Callendar appealed the idea of atmospheric warming. Concluding his article he speculated that the combustion of fossil fuels “is likely to prove beneficial to mankind in several ways, besides the provision of heat and power…..  Small increases of mean temperature would be important at the northern margin of cultivation, and the growth of favourably situated plants is directly proportional to the carbon dioxide pressure. In any case the return of the deadly glaciers should be delayed indefinitely.”

Callendar published his discoveries in a series of papers, but they did not raise any interest from the scientific community. Only, later, in 1957, just before the beginning of the International Geophysical Year (IGY) – the first global scale experiment that recognised the potential of satellite technology in studying the Earth -, Hans Seuss and Roger Revelle, although they believed “that it was absolutely impossible to have had a sufficient increase in the CO2 amount in this century”, they referred to the “Callendar effect,” defining it as “climatic change brought about by anthropogenic increases in the concentration of atmospheric carbon dioxide, primarily through the processes of combustion.” Suggestive of Callendar’s brilliance was the fact that years later, scientists forecasted that some countries (Russia, Canada, New Zealand) will gain form climate change through an improved capacity for growing food, and used his prognosis that to promote and gain political support for their research projects to study climate change.

James Rodger Fleming is a professor at Colby College and a leading historian of atmospheric sciences and weather prediction. He has written a really fascinated book.