In a 1938 contribution to the Royal Met Society Journal, Guy Callendar discusses the greenhouse effects of water vapour and CO2 before concluding that CO2 emissions are contributing to the recent global warming.
Table II in Callendar, G.S., 1938. ‘The Artificial Production of Carbon Dioxide and Its Influence on Temperature.’ Quarterly Journal Royal Meteorological Society vol. 64, pgs. 223–240.