Since climate change is such a big topic and the world is investing billions of dollars each year. Are there any controlled studies of CO2 as a greenhouse gas?

It's quite simple: build two 3mx3mx3m transparent cubes beside each other, one with CO2 at 350ppm, the other with CO2 at 700 ppm, record all the temperatures every hour, and compare them. It would be amazing to put those in Science Centers around the world. So the public can have a clear ideas on how CO2 induced climate change works.

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    $\begingroup$ At the scale of a small cube inside the atmosphere, temperature would probably be dominated by heat exchange with the surrounding air, not radiation balance. The Earth system as a whole behaves differently because essentially all energy inputs and outputs are radiation. However, the infrared absorption properties of CO2 are routinely analyzed in the lab. For example, organic carbon in water can be measured by burning the sample and measuring infrared absorption in the resulting air. $\endgroup$
    – damp_civil
    Commented Feb 8 at 19:27
  • $\begingroup$ This is a simple experiment you can do at home: youtu.be/Ge0jhYDcazY?si=Z0oX6xgVWp14Z_EH $\endgroup$
    – LShaver
    Commented Feb 8 at 19:42
  • $\begingroup$ @LShaver always think it's good keep skepticism of such basic experiments. The temperature difference seems extreme (about 63% higher)!? Beyond the control basics like: are the lights the same distance, same bulbs, same plastic, etc., wondering if this may more show specific heat capacity differences (CO2 heats up 19% faster for same energy, something entirely different from Greenhouse Effect, as it's not increasing energy in the system, just meaning CO2 gets to a higher T [also insignificant in our atm as it's such a tiny component]... or water vapor impacts (as H2O is also a vin+BS product) $\endgroup$ Commented Feb 11 at 5:41

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It may be possible to have a demonstration experiment that shows the absorptive properties of CO2 but not as described. Nothing so simple -

greenhouse effect diagram

It is important to consider that the greenhouse effect works within a depth of atmosphere from sea level to low to mid stratosphere, ie much greater distance than 3m (up to 20,000m)- albeit with declining density and effect as the altitude rises. The rate of current warming averages around 0.2 C per decade, with periods of 3 decades preferred to avoid misconstruing natural climate variability for a trend. That is not conducive to hour to hour or day to day or even year to year measurement; averaging of highly varying temperatures over a sufficient time that a longer term trend can be determined is required.

I think John Tyndall's equipment for testing the radiant heat absorption of gases including CO2 - that, as a consequence of explaining how Earth's average temperature could be what it was, laid the groundwork for understanding that human activities, especially fossil fuel burning could change it - does look the part -



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