Uh...NO...WATER is the “chief greenhouse gas” as it comprises 95% of all such, same!
CO2 averages 3.5%....so....RELAX!!!
“CO2 averages 3.5%”... of what? 400 PPM is 0.04% of atmospheric gases, listing it below argon. The standard measure of CO2 is in Hawaii and that is 0.038%, which to me is no real difference. Both numbers may be higher than a few hundred years ago by 0.01% but that doesn’t seem significant to me.
The earth has had periods in past millenia when the CO2% was an order of magnitude higher. If this came down, how did that happen? The global warming models all are based on a runaway green house effect with CO2 causing water vapor to increase.
Is your 3.5% number the percentage of green house gases in the atmosphere? If so I don’t know what if I agree but it sounds possible.