Doubling the CO₂ cools or heats?

We calculate the effect that CO₂ enhancement has on the radiative transfer in the Earth atmosphere. To this goal, we apply a recent algorithm developed by Wehrse and Shaviv. The calculation differs from previous calculations in that it includes several million molecular lines and in that it iterates for the temperature profile, so as to satisfy radiative equilibrium. The main result we find is that the effective optical depth of the CO₂ band at 14,000-16,000Å is of the order of unity, and that by increasing the amount of CO₂, the optical depth increases primarily at high altitudes. With it, the absorption of solar energy increases at high altitudes but it decreases at low altitudes above the planetary boundary layer. As a consequence, the temperature rises at altitudes of about 20km, it decreases at low altitudes, but the surface actually warms. Note that the calculation does not include yet the effects of convection, nor does it include indirect effects on the T such as through water vapor or cloud feedbacks.