Could I model global warming?

Question

If I filled one drinks bottle with air and one with carbon dioxide, sealed them both, placed them in direct sunlight and recorded the temperature inside the bottles, would the one containing carbon dioxide be hotter?

Answer 1

Both bottles will heat up, but the air around them will cool them a little so they will both reach about the same temperature  regardless of the CO2 content

Answer 2

No, the physics of global warming are much more speculative than that.

CO2 can't trap heat in a way that can be demonstrated.

The AGW theory involves a lot of theories about things that might occur in the upper atmosphere & chain reactions.  It more of an idea than proven science despite what a lot of people believe.

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Thinking about your experiment, using the sun as a heat source, you would not be able to absorbe any infrared radiation in the bands that CO2 absorbes because the CO2 in the atmosphere would filter it all out before it reaches the ground.  The reason is that CO2 is such a good absorber of radiation that the atmosphere is opaque to the 15 micron wavelength of radation.

If you used a heat lamp, you possibly generate enough 15 micron IR to cause a bottle of CO2 to warm up more than a bottle of air.  

  

If you're interested in science and not psuedoscience, here's a summary.  CO2 absorbs a narrow band of IR radiation at 15 micron wavelength (it absorbed 2 more bands also but these are not considered as significant).  

The Earth is believed to have a greenhouse effect in which some gases in the atmosphere absorbes radiation from the Earth which elevates the surface temperature of the Earth.  It's well know amonst believers and skeptics that the absorption of the 15 micron radiation band is absolutely staturated and virtually no 15 micron radiation gets through the atmosphere into space (as verified by satelite measurements as good scientists like to verify their theories with real world experiments), thus suggesting that significant warming from additional atmospheric CO2 is impossible.

To counter this, believers seem to have a magic molecule theory that in the upper atmosphere there is a thin layer of molecules that does something magical, which is not suppported by any published scientific papers.    

Take a look at J.S.'s answer for some psuedoscience not supported by any published papers.

Answer 3

I would not expect it to.  I was trying to explain this to someone else.  Being a greenhouse gas does not mean the gas itself gets hot.  That isn't what the greenhouse effect is.

CO2 absorbs on all frequencies, but emits in the infrared range.  That's what makes it a greenhouse gas, not some unusual heating/cooling property.

Answer 4

Not you again! I told you last time that CO2 will not get hot just being in the sun. Just putting air in a bottle gives you the "greenhouse" effect. The CO2 acts like the glass in a greenhouse.  It reflects the infra red radiation back into the atmosphere,instead of being radiated back into outerspace. CO2,itself DOESN'T get hotter.   Try your little experiment.  What will happen is the air in BOTH bottles will heat up! The bottles are just little greenhouses!  You obviously need more education in Earth Science.

Answer 5

Not that way.

The difference would be tiny, too small to measure.  Because the thickness of your layer of CO2 is WAY too small.  You can't fix this by putting more CO2 in, you'd just saturate the process.  It takes a very thick layer of atmosphere for this process to work.

Shapeshifter and littlerobbergirl are right on this one.  The only way would be with a box several miles high.

Answer 6

yes if you used big enough bottles.....

Answer 7

to be accurate both bottles should contain air but 1 should contain 1/3 of 1% co2 to match today's climate & the other should contain 1/4 of 1% to match the climate hundreds of years ago.

co2 is thought to be transparent to short wave radiation like sun light but will reflect the long wave heat radiation created when sunlight strikes the ground.

its supposed to to work like the glass in a green house & probably does on venus where the atmosphere is 95% co2 but the effect is negligable on earth where the atmosphere is only 1/3 of 1%. co2.

in your experiment the walls of the bottles will keep the heat from escaping so the contents wont matter unless 1 is dark & 1 is transparent.

Answer 8

well, it wouldnt accurately demonstrate the conditions of the atmosphere.  I saw a similar experiment, where they used air, and PURE CO2 in the other bottle, which got a whoping .7*C warmer than the air bottle.

But in the atmosphere, if there really were pure co2, we would all be dead pretty quick.  The experiment they did was very misleading, to anyone who doesnt realize that the atmosphere is not made up of, nor is anywhere near 100% co2.

If they did the experiment with regular air, and air with 100 more ppm of co2, then it would be accurate.

Answer 9

Remember that CO2 is transparent to visible light spectrum (sunlight), and only influences climate in the infrared (heat) spectrum as it's being re-radiated out to space.  Initially scientists screwed up and thought that water vapor played a significant role because they did not have accurate enough measurements and they misunderstood where the escaping heat energy was radiating from:

http://www.aip.org/history/climate/co2.h...

A few years after Arrhenius published his hypothesis, another scientist in Sweden, Knut Ångström, asked an assistant to measure the passage of infrared radiation through a tube filled with carbon dioxide. The assistant ("Herr J. Koch," otherwise unrecorded in history) put in rather less of the gas in total than would be found in a column of air reaching to the top of the atmosphere. The assistant reported that the amount of radiation that got through the tube scarcely changed when he cut the quantity of gas back by a third. Apparently it took only a trace of the gas to "saturate" the absorption — that is, in the bands of the spectrum where CO2 blocked radiation, it did it so thoroughly that more gas could make little difference.(7*)  



Still more persuasive was the fact that water vapor, which is far more abundant in the air than carbon dioxide, also intercepts infrared radiation. In the crude spectrographs of the time, the smeared-out bands of the two gases entirely overlapped one another. More CO2 could not affect radiation in bands of the spectrum that water vapor, as well as CO2 itself, were already blocking entirely.(8)

  

These measurements and arguments had fatal flaws. Herr Koch had reported to Ångström that the absorption had not been reduced by more than 0.4% when he lowered the pressure, but a modern calculation shows that the absorption would have decreased about 1% — like many a researcher, the assistant was over confident about his degree of precision.(8a) But even if he had seen the1% shift, Ångström would have thought this an insignificant perturbation. He failed to understand that the logic of the experiment was altogether false.

  

The greenhouse effect will in fact operate even if the absorption of radiation were totally saturated in the lower atmosphere. The planet's temperature is regulated by the thin upper layers where radiation does escape easily into space. Adding more greenhouse gas there will change the balance. Moreover, even a 1% change in that delicate balance would make a serious difference in the planet’s surface temperature. The logic is rather simple once it is grasped, but it takes a new way of looking at the atmosphere — not as a single slab, like the gas in Koch's tube (or the glass over a greenhouse), but as a set of interacting layers.

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Here's where they finally "got it":

Not until the mid-20th century would scientists fully grasp, and calculate with some precision, just how the effect works. A rough explanation goes like this. Visible sunlight penetrates easily through the air and warms the Earth’s surface. When the surface emits invisible infrared heat radiation, this radiation too easily penetrates the main gases of the air. But as Tyndall found, even a trace of CO2, no more than it took to fill a bottle in his laboratory, is almost opaque to heat radiation. Thus a good part of the radiation that rises from the surface is absorbed by CO2 in the middle levels of the atmosphere. Its energy transfers into the air itself rather than escaping directly into space. Not only is the air thus warmed, but also some of the energy trapped there is radiated back to the surface, warming it further.



That’s a shorthand way of explaining the greenhouse effect — seeing it from below, from "inside" the atmosphere. Unfortunately, shorthand arguments can be misleading if you push them too far. Fourier, Tyndall and most other scientists for nearly a century used this approach, looking at warming from ground level, so to speak, asking about the radiation that reaches and leaves the surface of the Earth. So they tended to think of the atmosphere overhead as a unit, as if it were a single sheet of glass. (Thus the "greenhouse" analogy.) But this is not how global warming actually works, if you look at the process in detail.  

What happens to infrared radiation emitted by the Earth's surface? As it moves up layer by layer through the atmosphere, some is stopped in each layer. (To be specific: a molecule of carbon dioxide, water vapor or some other greenhouse gas absorbs a bit of energy from the radiation. The molecule may radiate the energy back out again in a random direction. Or it may transfer the energy into velocity in collisions with other air molecules, so that the layer of air where it sits gets warmer.) The layer of air radiates some of the energy it has absorbed back toward the ground, and some upwards to higher layers. As you go higher, the atmosphere gets thinner and colder. Eventually the energy reaches a layer so thin that radiation can escape into space.

  

What happens if we add more carbon dioxide? In the layers so high and thin that much of the heat radiation from lower down slips through, adding more greenhouse gas means the layer will absorb more of the rays. So the place from which most of the heat energy finally leaves the Earth will shift to higher layers. Those are colder layers, so they do not radiate heat as well. The planet as a whole is now taking in more energy than it radiates (which is in fact our current situation). As the higher levels radiate some of the excess downwards, all the lower levels down to the surface warm up. The imbalance must continue until the high levels get warmer and radiate out more energy. As in Tyndall's analogy of a dam on a river, the barrier thrown across the outgoing radiation forces the level of temperature everywhere beneath it to rise until there is enough radiation pushing out to balance what the Sun sends in.  

While that may sound fairly simple once it is explained, the process is not obvious if you have started by thinking of the atmosphere from below as a single slab. The correct way of thinking eluded neary all scientists for more than a century after Fourier. Physicists learned only gradually how to describe the greenhouse effect. To do so, they had to make detailed calculations of a variety of processes in each layer of the atmosphere.

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Isn't it interesting that current denial propaganda comes from theories disproven in science over 100 years ago?  It's a pretty creative trick they use to find plausible-sounding junk.

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For an experiment to show that CO2 blocks infrared radiation you can fill a clear container with CO2 and try to shine an infrared remote (even a TV remote) through it.  If you put a digital camera on the other side with an infrared filter over the lens, it should not "see" the IR remote through the gas, but have no trouble picking it up through a similar container of air.  I believe some night vision systems operate in the IR spectrum, so you may be able to conduct the experiment with a camcorder that has a strong "night shot" mode.  CO2 is available in those little metal cannisters that are sold in dive stores to fill floatation vests and in hobby shops to power rockets, etc.  

The catch is that you'll need to shine the IR through a long enough distance in CO2 for it to absorb the energy.  (I don't know what that distance would be.)  You could try building a PVC pipe with clear endcaps, but you'll vents to insert the CO2 on one end and to allow the air it's replacing to escape on the other end.  If the experiement doesn't work, you probably needed a longer distance (if you use a wide enough pipe you can double the distance travelled by putting the IR source next to the camcorder and a mirror at the other end), but most science teachers would be impressed by the concept anyway.