This experiment should be carried out in a cold room, with the temperature set at least below 10°C (absolute 0 would be ideal, but a little uncomfortable)

1. First, set things up more or less as you would for most “climate change” demonstrations (with a few changes): Prepare two similar clear, thin, dry plastic bottles - empty a small pouch of desiccant in each - fill one with nitrogen (or any other radiation transparent gas), fill the other with CO2* - hang electronic temperature sensors** inside each, and seal the openings with putty. Place a 100W incandescent light bulb between the two containers, one inch away from each (at a filament temperature of around 2,700°C, the bulb duplicates incoming solar radiation in the visible and infrared range). This setup simulates the effect CO2 has on incoming solar energy (atmosphere-cooling potential).

2. A few feet away, duplicate the above setup, except use a specially prepared light bulb connected through a rheostat (Use a same size bulb as in #1; spray it first with metallic paint, then with black paint, making it a reasonably good “black body” - Note that it may be easier to maintain the required temperature with a low wattage bulb and a low voltage system) This setup simulates the effect CO2 has on the planet’s outgoing energy (atmosphere-warming potential).

3. Once all the components have reached room temperature (say 5-10°C), turn on the light bulbs and adjust the rheostat so that the bulb in setup #2 maintains a steady 15°C (monitored with an infrared thermometer); at that temperature, the bulb duplicates the planet’s black body emission spectrum.

4. Let things stand until the temperature in all containers stabilize (about an hour), record all temperature readings and subtract the nitrogen temp. from the CO2 temp. in each setup. Then double the result of the #2 simulation*** and compare it with the value obtained from the #1 simulation. The setup that shows the greatest temperature differential is dominant and determines whether CO2 is an atmosphere-warming gas or an atmosphere-cooling gas. Place your bets…

* The CO2 and nitrogen should be from compressed gas cylinders. Nitrogen, being radiation transparent, sets the baseline (ambient air contains H2O and many other RAGs). Most online “experiments” suggest producing CO2 by mixing vinegar and baking soda, or dropping a few seltzer tablets in water. This introduces water vapor into the mix and makes the results totally unacceptable.

** The temperature sensors need to be shielded all around with aluminum foil (not touching the sensors), with openings top and bottom to allow circulation.

*** The planet radiates spherically and continuously, whereas solar energy reaches only half the surface at any one time - doubling the result of the outgoing energy simulation therefore makes the results a little more realistic.

Ok, those gases are not the same molecular weight, there is no significant temperature and pressure gradient within the bottles (as there is in the atmosphere),  the gas concentrations are “abnormal”, etc., but this would still provide meaningful results since we’re looking for relative values, not absolutes - certainly more relevant than those you find online.

The same setup could be used to demonstrate the effects of water vapor on temperature by replacing the CO2 with H2O (simply pour a little water in the bottles and wait until the humidity within the bottle stabilizes).

And note that this experiment demonstrates how much heat RAGs absorb and transmit to surrounding gases, not how much is radiated back out - that would require a more sophisticated setup.

If a reader has access to the facilities and equipment needed to run such an experiment, I’d be very interested in the results. Those could be posted here.