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Emissions Estimation


English engineer and amateur meteorologist Guy Callendar concludes that humans have added about 150,000 million tonnes of CO2 to the air over the previous 50 years

“The artificial production of carbon dioxide and its influence on temperature,” a paper by Guy Callendar appearing in the Quarterly Journal of the Royal Meteorological Society, concludes that “by fuel combustion man has added about 150,000 million tons [tonnes] of carbon dioxide to the air over the past 50 years,” and estimates that approximately three quarters of that has remained in the atmosphere. Callendar concludes that this increase in carbon dioxide has caused an increase in mean global temperatures during the previous half-century: “From this the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.003oC per year at the present time.”* As physicist and historian of science Spencer Weart notes: “As for the future, Callendar estimated, on flimsy grounds, that a doubling of CO2 could gradually bring a 2oC rise in future centuries. Aware that industrial emissions were already far greater than in Arrhenius’s day, Callendar saw this warming as a matter of present interest….Callendar’s publications attracted some attention, and climatology textbooks of the 1940s and 1950s routinely included a brief reference to his studies. But most meteorologists gave Callendar’s idea scant credence.”**

*G.S. Callendar, “The artificial production of carbon dioxide and its influence on temperature,”Quarterly Journal of the Royal Meteorological Society, Vol. 64, Issue 275, April, 1938,
**Spencer Weart, The Discovery of Global Warming (Feb. 2016),


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