What a genius. Perhaps he was an alien?
Simply put: the scientists don’t know.
I think that the whole CO2 idea came from Carl Sagan who theorized that CO2 would cause a rise global temperatures. At least, he was the most prominant figure to claim it. Didn’t he use a dead, waterless, planet as his model? Seems like it was Mars but that doesn’t seem right.
Anyway....
The difference, of course, is Earth has life and much of that life consumes CO2. In addition, Earth has water and water vapor in the form of clouds which have a huge impact on retention of radiated energies.