CO2 was confirmed as a greenhouse gas 150 years ago - long before the climate change debate started in the late 1980s. The mechanics of how and why extra carbon dixiode in the atmosphere causes a temperature rise is trivial: CO2 absorbs infrared; then re-emits it.
But only some of the re-emitted infrared goes outwards, and some inwards back towards the surface. That re-emission back down IS the greenhouse effect.
That's precisely what the lamp on desk experiment disproves.
In order for energy to flow from the CO2 to the ground, the CO2 has to have a higher temperature then the ground. Like with current in electricity, there has to be a difference in potential for energy to flow. Second law of thermodynamics.