. Even with more CO0 per volume on Mars there are not enough molecules to store the energy emitted by the Martian surface so the CO0 does not warm up and emit a Downwelling flux to keep the surface warm. A thicker atmosphere will allow more energy to be stored in its mass. I think you should look at the link I provided Mike Flynn and geran that shows radiation and temperature data for various spots in the US and plot some graphs. 