[tathougies]

Your claim is that if you put CO2, a relatively easy to acquire gas, into a bottle, the temperature will keep climbing? Isn't this a violation of the laws of thermodynamics.

I'm not so sure your experiment would work unless you specify various other conditions. The main reason that CO2 is a 'greenhouse gas' is that it absorbs thermal infrared light. In other words, CO2 'reflects' infrared light. This, combined with the fact that the sun is continuously heating the earth means that -- in the context of the Earth's atmosphere -- CO2 acts like a giant blanket. Only in the context of a continuously externally heated object does CO2 cause temperature increases, which is not something that is necessarily going to be simulated by 'putting CO2 into a bottle'.

However, CO2 by itself does not cause things to heat up. That is patently ridiculous, and bad science. In fact, if you fill a jar with CO2 and water gas (also a greenhouse gas), and expose it to the air on a cloudless night, and then put some kind of insulating layer between it and the earth (like some feet of straw), it'll actually freeze: https://pazhayathu.blogspot.com/2012/02/water-cooler-air-con...

[fallingfrog]

https://youtu.be/Ge0jhYDcazY

This is a video demonstration. All you need is 2 bottles under the same amount of illumination with different amounts of co2.

Sorry, I should have said, under illumination, and the temperature will reach a higher equilibrium with co2 in it, but it will not rise without limit.

[_ph_]

I guess the previous poster was assuming the experiment taking place under a suitable light source like a halogene lamp, so the effect of CO2 in the atmosphere can be reproduced.

[tathougies]

But there's more than that... you'd also need a body of large thermal mass opposite the halogen bulb to absorb the heat, and then re radiate it, so it could bounce off the CO2.

[tejohnso]

I was thinking of a 12" glass sphere with an 11.5" black sphere inside of it. The black sphere would be the thermal mass (maybe full of water) and it would have temperature sensors all around. Then in the space between, some air. Get a baseline temperature reading. Then pump in a tiny amount of CO2. Check temperature delta.

I wonder if something like that has been done.

[tathougies]

The amount of change you would see from that is going to be really way too small to get an accurate reading on. You'd also need to run a control experiment with heating the ball with just plain air (rather than air + extra CO2), because the glass is also going to act like a greenhouse trap anyway.