[Ronaldus Magnus Reagan]

The kicker is that the CO2 in the first 10 or so meters of air absorbs close to 100% of the heat radiated by the ground in those fequencies. So if you doubled the CO2 in the atmosphere, THE SAME AMOUNT OF HEAT WOULD BE TRAPPED, just a little closer to the ground. In fact, you could increase the CO2 in the atmosphere by 100 times, and THE SAME AMOUNT OF HEAT WOULD BE TRAPPED, just closer to the ground.

I've read that the atmosphere of Mars is such that the temperature varies greatly just a few feet off the surface. Your feet might be in 70 degree warmth, but your head will be at 30. Have you heard this also?

[piytar]

yup, has to do with the much thinner atmosphere = no significant heat trasfer via convection.