Honestly, one of the nails in the coffin for me about the whole CO2 thing was this image from NASA.
This is a satellite overlay from 2016 of the actual CO2 concentrations over the US, NOT an averaged-out global map. You see, CO2 is heavier than O2 and N2, and it doesn't mix well in the atmosphere, so far from creating a blanket over the whole earth, CO2 actually just exists in high concentrations in pockets. So using the laws of thermodynamics, which say that heat will flow toward cooler areas, the CO2 in the atmosphere can't possible be trapping heat, because there are huge holes in the "blanket". Even supposing that CO2 does have a warming effect where it is concentrated, that heat will just flow out to cooler areas, with less CO2, which means it can't possible be warming the whole earth.