I have to admit that I am skeptical about how much climate change can be attributed to the human controlled proportion of green house gasses… but it doesn’t really change anything. The same so called causes of Global warming (Industrialization) are the same causes of massive poisoning of the earth, along with all of the economic turmoil that we are living through. The solutions and preparation that would be needed to combat climate change are the same solutions that we need to reverse soil degradation, move toward sustainable water and energy use and ultimately build more biomass for our bumpy ride.

There is no need to argue.

Oh please.

0:51 does not exactly look as if CO2 were added to a tightly sealed bottle.

Note also particular that after the time jump at 01:00 in the video, the right (from the viewer’s perspective) bottle is closed with a normal cap. So, how was this put onto a pressurized bottle without equilibrating the pressure?

Apart from that, considering the other issue you raise – have you done that experiment and can you link to a video that proves your claim?

This test should be repeated but with 4 different gases.

One bottle with argon,(non-greenhouse gas), one with air, one with CO2 and one with Methane. Argon comes out with the highest temperature and Methane, (the more powerful greenhouse gas) comes out with the lowest.

Explain this.

http://www.permaculture.org.au/images/genetic_engineering2.jpg

We’re all excited that we’ve understood one little element of the puzzle, but can’t see how that single piece fits into a far bigger picture. Indeed, we don’t even realise there is a bigger picture. Worse, as we ‘cleverly’ mess with/manipulate that single piece, we discover knock on effects we didn’t anticipate.

When we step back, to look at/observe interactions/relationships/balance in natural systems, we see we don’t have to understand all the minutiae to know that we’re messing with a system that worked perfectly for thousands of years until now. We know the oceans are acidifying through increase in carbonic acid, we know this is from excess CO2 in the atmosphere. We know we’ve cut down far too many trees (releasing their CO2 and removing their CO2 sequestration services) and are releasing more CO2 into the atmosphere via fossil fuels than at any time in known history, etc. I find it fascinating when I hear, for example, denialists using the argument that we’re a ‘carbon starved world’ (http://permaculture.org.au/2009/3/31/capping-c02-emissions-will-steal-plant-food/ ), making me wonder how all the trees we had a few centuries ago could ever have survived. The few trees we have left now must be soooo happy all the other trees are gone. It’s the same mindset that has people removing ground cover and cutting down trees because they believe the plants are competing with them for water, then discovering after they’ve done so that everything around them dries up. This is complete reductionism and ignorance about natural systems and their services.

*sigh*

1.: In the video, I see three numbers: 23.4 degrees Celsius at the beginning, 31.2 degrees Celsius for the air bottle at the end, and 36.1 degrees Celsius for the CO2 bottle. Looking at the computer screen as shown at 01:56, which shows a cut-off graph, I think it is somewhat reasonable to assume that these are the final equilibrium temperatures.

That gives 7.8 Kelvins of heating for the air bottle, and 12.7 K for the CO2 bottle.

Now you write:

“Therefore, the contents of the carbon dioxide bottle will heat up 23.3% faster than the air bottle.

If you plot the rates of temperature increase in the two bottles and take the ratio of those rates, you will find that the entire effect is fully explained by the ratio of the molecular masses.”

from these numbers (and also, estimating slopes on the cut-off graph shown), I’d say that the ratio is certainly larger than 1:1.25. So, where is your 23.3% there?

2. Have you considered doing a simple check of your calculation against a materials property table? I’ll use the same source as you here, engineeringtoolbox.com:

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Thermal conductivity of air at NIST STP is 0.024 W/m K, that of CO2 is 0.0146 W/m K, giving us a ratio of 1.64, rather than 1.23. (Incidentally, that correct ratio is pretty close to the ratio of the temperature increases observed here – but for now, I’d consider that a coincidence, for that ratio will surely depend on the thickness of the insulating gas blanket.)

3. You are perfectly right that, all other things being equal, thermal conductivity goes with the inverse square root of the mass of the molecule. The noble gases obey that law somewhat
nicely: For Argon and Helium, mass ratio is about 10:1, and conductivity ratio is about 1:3. However, what you seem to be unaware of is that heat conductivity also is proportional to the molar specific heat capacity at constant volume. (Intuitively: the number of thermal degrees of freedom transported per particle.) Oxygen and Nitrogen are pretty close to the expected value of 5/2 R for a linear molecule (2 rotational + 3 translational degrees of freedom, each contributing k/2 per molecule), while CO2, due to excitations of internal degrees of freedom, has a larger Cv of about 3.4 R. That’s a factor 1.36 you just omitted. In addition to this, thermal conductivity is proportional to the mean free path of the molecule, which is inversely proportional to its cross-section. The CO2 molecule evidently has a much larger effective diameter than both N2 and O2, hence a smaller mean free path. Another factor you did not take into account when comparing air and CO2.

Just out of curiosity: may I ask what subject you did your PhD in?

Forgive me for not including it specifically in the previous post, but here is a reference where the calculation is shown in detail: http://www.chem.arizona.edu/~salzmanr/480a/480ants/collsurf/collsurf.html

For reference:

Air molecular mass:
http://www.engineeringtoolbox.com/molecular-mass-air-d_679.html

Carbon dioxide molecular mass:
http://en.wikipedia.org/wiki/Carbon_dioxide

Ideal gas law: http://en.wikipedia.org/wiki/Ideal_gas_law
Gives density as being proportional to the ratio of the pressure to the temperature. For the same initial conditions of pressure and temperature in the same size bottles, the density (and number) of molecules are the same.

Ratio of molecular mass: 28.97/44.01 = 0.6583

Kenetic theory of gases:
http://en.wikipedia.org/wiki/Kinetic_theory_of_gases
Gives the mean velocity as the square root of the ratio of the temperature to the molecular mass.

Inverse square root ratio of molecular mass:
sqrt(44.01/28.97) = 1.233

Number of collisions with a wall:
http://www.wikidoc.org/index.php/Kinetic_theory
Gives the number of collisions as being proportional to the product of the density and mean velocity. Since the initial densities are the same (see above), the ratio of the number of collisions is equal to the ratio of the velocities. At the same temperature, this is the ratio of the square root of the molecular masses, i.e., 1.233.

I fail to see how this is “quite wrong in more than one way”. Note also, that it is not I that am “quite wrong” in your assessment; it is J. Herapath who detailed the calculation in an 1816 paper entitled “On the Physical Properties of Gases” in the Annals of Philosophy (pp 56-60).

I think you have have a valid point here. While for the earth, radiation is the only cooling mechanism, we also have conduction and convection in this simple experiment.

So, if we strip out your numbers, which superficially appear very accurate, coming with 3 or even 4 digits, but unfortunately are quite wrong in more than one way, your basic claim as I understand it is that, in such a set-up, the non-air bottle will always heat to a higher equilibrium temperature than the air-filled bottle if we put in a heavy gas.

Hence, what we actually would have to compare in this experiment is the CO2 warming (relative to air) and the warming (also relative to air) produced by a non-IR-active gas of about the same molecular mass, heat capacity, and – preferentially, effective radius – as CO2.

Unfortunately, it is a bit difficult to actually do such a differential experiment here. Pondering over the periodic table, I don’t see an element or compound that could fit the bill. The closest analog may be Krypton, which, however, only has about 1/2 the heat capacity of CO2.

Perhaps the experiment should be re-done in such a way that the heat conduction playing field is leveled by also putting 50% helium into both the air and CO2 bottle then.