Hemispheric and Global Mean Temperature anomolies presented by Guy Callendar to the Royal Meteorological Society in 1938. The dotted line marked ‘CO2 EFFECT ON MEAN gives the amount of the warming attributed to CO2 emissions.
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. This chart is on page 233.