I guess radiative properties of CO2 in the lab, that was already thought of centuries ago. Also the concentration of CO2 in the atmosphere plotted against time

I guess radiative properties of CO2 in the lab, that was already thought of centuries ago. Also the concentration of CO2 in the atmosphere plotted against time. It was news back then and some people started getting worried because of that. Since Keeling started measuring it in 1958, it took some years for the trend to show.