Is CO2 Really a Greenhouse Gas?

This video was sponsored by Wren

I show you an easy experiment to test if CO2 is really a greenhouse gas.

[Schneejungs]

I was teaching Physics last year and tried this experiment. After half an hour there was no diffrence in temperature. Even though I was using plastic containers and an infrared lightsource. I came to the conclusion this experiment sucked and wanted to leave it out in the next years...
But I really like your simple setup! I will definitly try this in class.

[robadkerson]

I love how simple these setups are sometimes. Literally duct taping a handheld infrared sensor pointing it at a hot plate on its side. And yet, it's perfect

[GeeTrieste]

1. The volume of air has to be the same as the volume of the CO2 in the bag.
2. A more accurate and less ambiguous way to do this, is put the IR thermometer and the heat source within a clear box with the same dimensions as this experiment, then start with air in the box, then displace it with CO2, then report to us all the change in IR emission from the heat plate detected by the IR thermometer, as the air is displaced.
3. This experiment only shows the transmissibility of the various gases, as you mention, it could also be showing that CO2 is a great reflector of IR light, not necessarily an absorber.
4. Given enough time and insulation from the rest of the room, the CO2 should actually heat up to the same temperature of the heat source, and then re-emit the same amount of heat ostensibly absorbed.

[GeekIWG]

Would be cool now to see this experiment done with other gasses, including both those that are considered greenhouse gases and those that are not. Air with different humidity levels would be interesting to test as well.

[darthhodges]

I have heard the argument that the amount of water in the air contributes more to the greenhouse effect than CO2. You could check that using a similar setup but with two bags of air. One with a desiccant pouch and the other with a small amount of water added. Let the bags sit for a while to maximize the difference in humidity and then see if that makes a difference. Preferably also compare it to a CO2 bag again to actually test that argument.

[thomasetavard]

No one is denying CO2 is a Greenhouse gas. Your experiment used a very high concentration of CO2 with comparatively very little absorption/temp reduction in temp.
In earths Atmosphere has a very low CO2 concentration of Approx. 400 parts per million or 0.04% and if it was doubled it would only be at 0.08%. The temperature difference between those levels would be so miniscule it wouldn't be able to be registered.

[balaam_]

Wouldn’t be the first time Bill Nye was wrong.

[brandonbest]

He checked the science the same way you check a math problem and solution you riddled out. He rearranged the dynamic to prove the concept in an alternative way. That's the kind of stuff that really makes me enjoy this channel.

[DAVID-ionj]

According to a video from CDN youtube chanel featuring a climate science researcher, WATER VAPOR is the most important agent in affecting climate. By far since there is just so much more of it in the atmosphere.And that researcher was exploring the effect of CO2.

[sdkee]

Fun fact: Nye photos hopped his thermometer shots. Every pixel in both thermometers was identical except the red lines. Nye is not just confused, but when his experiment didn't do what he wanted he just faked the evidence.

[Eremon]

Bill Nye isn't exactly the guy I go to for facts.

[JimGriffOne]

Does the IR thermometer read a single wavelength or is it measuring broadband IR? Also, if you have an atmosphere if 100% CO2 and there's only a tiny differential, how about testing it with 0.02% vs 0.04%? What difference will be visible, if any? Surely it'll be well into the noise floor of most measurement systems and would require extremely sensitive spectrometers. Then comes the question of comparing radiative warming vs diabatic at surface pressure (101kPa). Most studies I've seen prove that radiative warming of the atmosphere is an extremely small amount and diabatic (and adiabatic) completely swamp out any radiative warming in most layers of the atmosphere (bar the ionosphere/thermosphere). Also, on planets with near 100% CO2, there's a huge disparity. Venus (obviously closer to the sun) is much hotter than Mars (further away), but it is only hotter due to diabatic heating of the atmosphere. Its pressure is 90x that of Earth, vs Mars's atmosphere which is much less dense at 0.6% of Earth's atmosphere. Diabatic and adiabatic heating completely swamping out any radiative heating.

[brandonfranklin]

I bet an entire channel worth of content could be created illustrating all the times Bill Nye was wrong, lol! Great video as always;)

[tribalismblindsthembutnoty]

Lets start with this: The 'runaway greenhouse effect' is not talked about anymore because we found out that co2 was much higher in most of earth's past and we never had a runaway effect then, so it will not happen now. In fact, phanerozoic co2 follows temperature by 800-3000 years. This means that temperature happens first, then the carbon cycle of our planet adjusts accordingly. Colder water stores more co2. It is really simple. It is NOT the co2 affecting temperature. Now, some may argue that with higher co2, even though the plants and animals of the time could take it, we can't. In fact, the co2 outside is 400ppm and inside its 1000 ppm. In an office building it can be 2000 or 3000 ppm. We can easily stand co2 levels from a quarter of a billion years ago. In that time, when co2 was high, plants and animals were bigger. You see, co2 is plant food. Thats it. Plant food. Now, if you flooded the entire atmosphere with it, maybe you would have some warming. But at 400 parts per million, just a mere 200 ppm away from a mass die off event, we are ok.

[drd]

The plastic bag experiment worked because of the choice of bag material. The bags appear to be PE polyethylene (CH2)n which has significant absorption only at C-C stretch C-H stretch (and smaller absorption at CH2 wag) all different from C-O stretch and O=C=O bend from CO2. Plastics with more complex structure (and more absorption bands) will absorb to more wavelengths and the difference between CO2 and air bags will diminish or disappear. Also, most glass is transparent to IR for wavelengths shorter than about 6 microns. Glass is a good greenhouse material because most blackbody radiation is at wavelengths longer than 6 microns for earth temperatures.

[zecuse]

A minor point that wasn't stated outright, the Ziploc bags do absorb a small amount of IR radiation, but as demonstrated with the glass, not all of it. Since both gases are in Ziploc bags, they'll both have the same additional absorption and any difference we then see between the gases will show that CO2 actually is a greenhouse gas.

[nydabeats]

How do we know that the co2 is absorbing the IR and not reflecting it? It would still create the same effect by not allowing some of the IR through the bag.

[daelrance]

Using the results of this experiment, what would the heat retention of Co2 be compared to air?

At night the Commercial Greenhouse's have to heat them to maintain the temperature, probably because of the construction of the walls which remove the heat. Sand is a fantastic absorber of heat but at night temperatures in the desert can get below freezing, despite temperatures of over 40 Deg C during the day. With sand you only have to bury your hand 10cm below the surface and it will be much cooler than the surface.

Just because something absorbs heat does not mean it retains it. Water absorbs heat and retains a huge amount of stored heat over night. A trip to the local pond with a pair of IR Thermal goggles, just before sun up proves this.

Suddenly this simple proof of a Greenhouse Gas absorbing heat is raising questions about its ability to retain heat. Particularly during the night when the IR source is turned off.

You have a bag of air, a bag of Co2. Apply your IR source for a set time. measure the heat of each bag, then remove the IR source and see which one retains heat for longer.

[winterburden]

I can't believe Bill Nye never even verified his statement 🙈

[andrewwallace]

Would love to have seen the empty bag, control test, so we'd know how much the plastic absorbed.