Additional CO2 molecules can not magically create more heat energy. They can not increase the energy level of molecules at the same or higher energy level, e.g. putting an ice cube in hot water does not warm the water. Adding water at the same temperature does not warm it either.
The IR energy absorbed by the CO2 molecules is emitted in all directions equally. Ignoring IR energy lost to collisions, because the planet surface is curved, less than 50% CO2 emitted radiation can be returned to the surface. The amount that doesn't get returned by each molecule must increase with height.
Adjacent to the emitting surface, the energy returned by additional molecules cannot raise the level of the receiving surface above its original temperature, it can merely delay its cooling by fractions of microseconds, if at all. Subtract the energy lost to collisions (thus subject to convection), the delayed emitting surface cooling likely becomes fractions of microseconds.
Rising higher above the surface, all bodies emit radiation. Additional CO2 causing more collisional transfer due to its increased population must accelerate the upward movement of heat energy by convection. The IR energy moving downwards as radiation emitted by non CO2 molecules (+ aerosols and cloud) absorbed by CO2 must increase and as already mentioned, each stimulated molecule emits more in the direction of space than down because of the curved atmosphere. In the atmosphere, CO2 enhances both radiative and convective upward energy movement.
Unlike water vapour, CO2 cannot store energy. CO2 intercepting IR in the overlap ranges avoids the energy being stored.
The above implies additions to the CO2 volume have a small cooling influence.
Vostok ice core data shows that Antarctic CO2 follows temperature increases and decreases by 600-1200 years. (Yahoo search it.) That implies current increases are mainly due to MWP and earlier, warm eras.
A tube filled with air minus CO2, then with CO2 in a proportion relative to the atmospheric level of preindustrial CO2 and then with a proportion relative to double preindustrial volume would show that the delay caused to IR travelling through the tube would need special equipment to detect. The change in temperature would need special equipment to detect. Of course this is not an original concept.
Look here: http://www.john-daly.com/artifact.htm (bear in mind the experiment assumes a flat earth.)
Other ideas and observational data that contradict the evidence free dogmatic, polarised, blinkered and tunnel visionary's alarmist view of CO2 additions having a significant influence:.
AGW by CO2 floored
Why Carbon Dioxide is Not a Greenhouse Gas
CO2 is not a Greenhouse Gas
Evidence of the CO2 influence on climate
Studies and Reports contradicting a dogmatic belief in the super demon molecule's ability
There are so many more:
Astute observation - 2
CO2 nonsense = 79 billion dollar + p.a. last year (money from?) plus whatever was gifted to 3rd world corruption by EUthenAsia power crazed (money from? Check your fuel bill. Check your energy bill. Check your food bill. Check your airplane ticket price.)
Astute observation - 3
Winters are not getting warmer. Summers are not getting longer. The weather is not getting calmer. The planet is not getting warming! CO2 is increasing. CO2 cools. Insignificantly.
Astute observation - 4 possibly one of the most important.
Why I am an Anthropogenic Global Warming Sceptic
An Aussie scientist in the field
I am a Skeptic
Why are we told CO2 is a GHG that warms? It fulfills the specs for a GHG in that it absorbs and emits IR. That additions increase IR radiation to space make it an anti GHG GHG!