Before multiplying CO2 emissions by 10, this was already in the papers:

"The temperature effect of CO2 may be considerable in a few centuries", 1912

Before multiplying CO2 emissions by 100, this was already in the scientific meetings:

"An atmosphere of [carbon dioxide] would give to our earth a high temperature; and if as some suppose, at one period of its history the air had mixed with it a larger proportion than at present, an increased temperature…must have necessarily resulted."