The amount of CO2 in the atmosphere is .04% ( that is not a mistake .. it is .04 percent .. or .0004 of the total volume of atmosphere ). There is a direct linear correlation between heat, and temperature. It is called a thermometer. Lets say a Centigrade thermometer or 0 to 100 degrees. My question: at .04% how much of 1degree C does CO2 manage ? And given that answer, how much would the % of CO2 have to change to raise the temperature of our atmosphere by 3 degrees C ? And if the rest of the atmosphere is 8.5 times more efficient at holding heat, then how much CO2 would be required ? The 8.5 belongs to water vapor. ( thank you .. and stay out of trouble ! )