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Gary Novak argues (e.g. in his book, Science Errors and on his web site) that climate models are incorrect, because of a missing "dilution" factor.

Climatologists skipped over the dilution factor. Each CO2 molecule in the air would have to be 2,500°C to heat the air 1°C—an impossibility—because there are 2,500 air molecules around each CO2 molecule (400ppm). There cannot be greenhouse gases creating global warming for this reason.

Is this statement true?

Sakib Arifin
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James
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    The claim is quite a bit silly. It shows a severe lack of understanding of the well understood, well researched field it is referring to, basically turning this into a science question that needs to be answered with a couple of physics lessons. I don't think there is much to salvage here. I'd vote to close this as off-topic and redirect the OP to physics.SE or somesuch. – DevSolar Dec 09 '16 at 08:28
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    @James: I am sure you will find the [atmosphere of Venus](https://en.wikipedia.org/wiki/Atmosphere_of_Venus) a fascinating subject. Greenhouse gasses and their effects are well-researched, and well understood. The **valid** questions regarding climate change and the human influence on it are about *quantities*, points of no return, and scope, not about the basic mechanics. Ref. [Is CO₂ the cause for Global Warming?](http://skeptics.stackexchange.com/questions/3435) – DevSolar Dec 09 '16 at 08:31
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    @DevSolar: [Novak's about page](http://nov79.com/about3.html) explains he has a Masters in Biology, and physicists don't take him too seriously. "In 1983, I found that energy was misdefined in physics. After arguing with physicists and getting nowhere, I developed a mathematical proof of the error, which of course got nowhere also." – Oddthinking Dec 09 '16 at 08:44
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    The web-site goes on to compare greenhouse gasses to bricks, where mirrors would be a better analogy, but I can't see how to turn this into a referenced answer. – Oddthinking Dec 09 '16 at 08:46
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    @Oddthinking: Kind of like young-earth creationism. You just don't know where to start (and whether it's worth the effort). ;-) – DevSolar Dec 09 '16 at 08:50
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    I know it has to be wrong, but I'm kind of curious as to why it's wrong. – Andrew Grimm Dec 09 '16 at 09:22
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    @DevSolar "Shows a severe lack of understanding of the field" sums up most of the global warming denial arguments pretty well. – Shadur Dec 09 '16 at 09:25
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    @AndrewGrimm: Without going into the specifics of how it really works... your microwave heats up your food without any part of the microwave oven getting as hot as the food, yes? I don't say that is how greenhouse effect works. I just use this to demonstrate how flawed the reasoning of the claim (that each CO2 molecule would have to be heated to 2500 degrees so it could heat the air around it by one degree) is. As if you would need to *first* heat the molecule to that ridiculous amount *before* it heats the air around it. The claimant is trying to ridicule the concept to push his agenda. – DevSolar Dec 09 '16 at 10:09
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    A classical example of [not even wrong](http://rationalwiki.org/wiki/Not_even_wrong). – gerrit Dec 09 '16 at 10:38
  • He seems to have missed that greenhouse gases actually *cool* the air. They heat the surface. – gerrit Dec 09 '16 at 10:40
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    @Oddthinking mirror isn't a good analogy, because once a CO2 or H2O molecule absorbs IR light, there is no preferred direction for the energy to be emitted. A better comparison would be adding a dye to a glass of water. The greenhouse gases (mostly H2O and CO2) are like a dye, but absorbing in the IR range instead of the visible range. – DavePhD Dec 09 '16 at 12:28
  • The best comparison is glass, which allows heat through as high frequency radiation, but prevents lower-frequency radiation from passing through - hence the name 'greenhouse gas'. – DJClayworth Dec 09 '16 at 18:31
  • @DJClayworth But glass is 100% glass, so it doesn't capture the 400 ppm aspect of the claim. – DavePhD Dec 09 '16 at 19:32
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    This is like saying that, because the heater in your house is 0.1% of the mass of your house, it has to be at a temperature of 1000 degrees to warm your house one degree. – Paul Johnson Dec 09 '16 at 21:23
  • @DavePhD: Agreed, re: mirror. Just an analogy that can be taken too far. I considered the glasshouse analogy too - the "ppm" comparison must be between the weight of the glass and the weight of the air trapped inside. I intuit that the glass would need to be way too hot to touch (if the hypothesis was right). Seemed too hard to calculate, and retain the simplicity of the comparison. – Oddthinking Dec 09 '16 at 21:32
  • @DavePhD: But we could (conceptually, anyway) make a mirror of say plastic that transmits 100% of both visible and IR, then apply an IR-blocking film that is 0.04% the mass of the plastic. (Indeed, something similar is done with digital cameras, to prevent IR from affecting the picture.) – jamesqf Dec 10 '16 at 04:04
  • @jamesqf yes, that would be very similar – DavePhD Dec 10 '16 at 13:08
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    I read his ["proof" that energy is misdefined in physics](http://nov79.com/en/ener.html). Yeesh. Short summary: he doesn't understand energy, thinks it must work like momentum, and therefore derives that it must *be* basically the same as momentum. It's wrong from start to finish. – Gordon Davisson Dec 11 '16 at 07:52
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    Wow, this guy has absolutely no understanding of the basics of physics and glorifies his own ignorance. – Sklivvz Dec 11 '16 at 20:20
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    Maybe the title of his book "Science Errors" was in reference to the examples he'd generate, himself. – PoloHoleSet Dec 12 '16 at 15:34

3 Answers3

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Each CO2 molecule in the air would have to be 2,500°C

This is wrong because molecules collide with each other, transferring their kinetic energy.

As explained in Elements of Physical Chemistry by Atkins et al.:

the collision frequency of a typical gas is about [1,000,000,000 times per second] at 1 atm and room temperature, so the time in flight in a gas is typically 1 ns [nanosecond]

So a given molecule (such as a CO2 molecule) can not have a higher kinetic energy than the other molecules in the gas for more than the nanosecond time scale. Instead, the energy is distributed among the molecules by collisions.

For more information see Properties of Gases.

Separately, the claim is wrong to compare the full 400 ppm of CO2 to only 1°C.

Instead, without a greenhouse effect, Earth's temperature would be -18 °C compare to the 1951 and 1980 temperature of 14 °C.

So the total greenhouse effect is about 32 °C, and CO2 is responsible for 9-26% of the effect. H2O is the main contributor, at 60%, according to the American Chemical Society, but humans do not control H2O concentration, except by otherwise changing temperature.

More particularly, the 32 °C of greenhouse effect, based upon the average 1951 and 1980 temperature of 14 °C, should be compared to the corresponding CO2 concentration of 320 ppm in 1965. Increase in temperature since then should be compared relative to increase in CO2 concentration since then, while considering any hysteresis effects (such as time for oceans and ice to equilibrate to new temperature).

Also, the claim is wrong to assess that only the air needs to be heated to the new temperature. The heat capacity of the ocean is much greater than the atmosphere.

DavePhD
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    The statement is definitely wrong, but it does actually make physical sense. If we assume the math checks out, then if magically the CO2 molecules gained energy until they were at 2500 C instantly, then those collisions would distribute that energy, and (again, assume the math was actually correct) that energy would equal a 1 C increase in average temperature for Earth. That logic is a Solid what if scenario. Of course, Global warming does not work like that at all, which is why its still wrong. – Ryan Dec 09 '16 at 21:44
  • @Ryan but it would need to be much more than the energy corresponding to 2500 C, because with zero CO2 the Earth would be much colder than the coldest ice age. The claim is additionally wrong for comparing the full 400 ppm to 1 degree C. – DavePhD Dec 09 '16 at 22:12
  • I dont think he actually compares 400 ppm to 1°C in any way, shape, or form. He is actually using the most basic of math ideas. 400 PPM means 2500 molecules of air per CO2 molecule (1M/400 = 2500). So, if one molecule of air (CO2) increases by 2500°C, that is kind of equivalent to 2500 molecules of air increasing by 1°C, from a basic logical standpoint. So there is no claim about the relationship between PPM and °C, nor an implication that 800 ppm would mean 2°C. It looks like your giving the claim too much credit here. – Ryan Dec 12 '16 at 17:22
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No, it's not true. Here's a 60-second explanation of global warming.

It's conservation of energy. Fourier asked in 1824: the earth receives a continuous stream of energy from the sun. Why doesn't it keep getting hotter and hotter?

The answer is that the earth also radiates heat into space. A warmer object radiates more heat, so the earth warms up to a temperature where the incoming solar energy and the outgoing thermal energy balance each other ("equilibrium temperature").

As long as the incoming energy and outgoing energy balance each other, the total amount of energy in the system (land, oceans, atmosphere) remains the same, and the climate remains stable.

Hasn't climate changed in the past? Yes: if the brightness of the sun changes, or if there's variations in the earth's orbit, or if the reflectiveness of the earth changes, or if volcanic activity changes the composition of the atmosphere, these can all affect the energy balance, and therefore make the equilibrium temperature higher or lower.

But we can measure all these things, and right now only one of them is changing dramatically: atmospheric composition. By digging up and burning vast quantities of fossil fuels, releasing fossil CO2 into the atmosphere, we've been acting like a giant super-volcano.

Tyndall reported in 1861 that carbon dioxide blocks thermal radiation. The CO2 molecules absorb thermal radiation and re-radiate it in all directions, so some of it goes back downward towards the earth.

You can measure this in a lab, as Tyndall did, by shining infrared through a vessel of CO2. You can see it in the atmosphere: we have satellite measurements showing that outgoing thermal radiation has declined since 1970.

So incoming energy > outgoing energy. Additional heat accumulates until a new, higher equilibrium temperature is reached.

It takes a long time for the actual temperature to catch up with the equilibrium temperature. (Tyndall: the atmosphere acts like a dam thrown across a stream, the water rises behind the dam until it reaches the top.) So even if we could stabilize the current CO2 level today, the temperature will continue to rise.

Novak's argument that CO2 molecules are too diluted to have a significant effect is incorrect. By reducing outgoing thermal radiation, the elevated CO2 level increases the equilibrium temperature at which incoming energy is balanced by outgoing thermal radiation. It has nothing to do with the temperature of the CO2 molecules themselves.

Because there's lots of random variation in temperature across the earth, what we see isn't a small uniform rise in temperature. Instead we see local or regional heat waves which are far hotter than in the past, like the 2003 heat wave in Europe which caused 70,000 premature deaths. For a more detailed view of the evidence of heat waves, see Hansen Sato Ruedy 2012. Figure 3 is especially remarkable.

Policy implications.

Russil Wvong
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  • The part of this answer that says "we have satellite measurements showing that outgoing thermal radiation has declined since 1970" is incorrect. The linked source took Fig. 1c. of Harries et al., which is captioned "component of simulated spectrum due to trace-gas changes only". The actual data is Fig. 1b. which shows an increase in outgoing radiation throughout the ~730-1030 range. http://www.nature.com/nature/journal/v410/n6826/pdf/410355a0.pdf – DavePhD Jun 02 '17 at 10:55
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It has been amply demonstrated that global warming is in fact happening, e.g. http://data.giss.nasa.gov/gistemp/graphs_v3/ Therefore it can't be impossible :-)

The mechanism by which it happens has been known since the early 20th century: http://earthobservatory.nasa.gov/Features/Arrhenius/ The predictions of climate models are reasonably close to what is actually measured, e.g. http://www.nature.com/nclimate/journal/v4/n9/full/nclimate2310.html

jamesqf
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  • "in theory, practice is the same as theory; in practice, they are different" comes to mind – Sklivvz Dec 10 '16 at 06:45
  • @Sklivvz: I think you need to explain that comment a little, because in practice what's predicted by theory/models is indeed reasonably close to what's observed. And the predictions get better when more accurate input data becomes available... – jamesqf Dec 11 '16 at 18:41
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    Absolutely -- I was referring to Gary Novak's theory being disproven by the simple fact that climate is warming. – Sklivvz Dec 11 '16 at 20:11
  • The general mechanism by which warming happens isn't disputed much even by most climate skeptics. But whether existing models give *good* predictions is widely disputed even by some non-skeptics. Though the nature article you quote argues models are good, it does so because several mainstream scientists have argued the opposite. We can hardly consider the issue resolved (however irrelevant to the question here). – matt_black Dec 12 '16 at 17:38
  • @matt_black most of that is based on things that climate modellers don't claim to be able to do with high accuracy (e.g. quasi-decadal projections, which are dominated by internal climate vairability, e.g. ENSO, rather than long term changes in radiative forcing - e.g. anthropogenic GHGs). There is a great deal of scientific agreement on the things that matter, such as equilibrium climate sensitivity, on which the models are thought to do well. Not making the distinction is a good way of suggesting the uncertainties are more problematic than they actually are. Plus ca change... –  Dec 14 '16 at 11:28
  • @matt_black - If X-amount of warming has already been demonstrated to happen, the precision of future predictions and whether they are perfect now really shouldn't factor into denying that the phenomenon exists. – PoloHoleSet Jun 02 '17 at 15:22
  • @PoloHoleSet Who denied warming is happening? It wasn't me. But I have a lot of skepticism about large computer models of anything. Climate models predictions of how much warming there will be are not that good in the opinion of some actual scientists. We don't need them, however, to *observe* that warming is happening or that the original question here is ridiculous. – matt_black Jun 02 '17 at 15:41
  • @matt_black - there are ***legions*** of people who deny it is happening. The climate models are on of many BS reasons for doing so. The models aren't mean to be exact predictions, and are always expressed as a *potential range* and are constantly undergoing refinement. With today's measurements, many perfectly valid estimates of physical phenomenon seem crude. Also, since the rate of CO2 going into the atmosphere is beyond the power of models to predict, claiming the models are flawed because their models were based on other assumptions isn't a fair criticism. – PoloHoleSet Jun 02 '17 at 15:46
  • For the most part, the models seem to have *under*-predicted the impacts, so pretending that the situation is not as bad as forecasted because of a general dissatisfaction with exact precision is not exactly an honest criticism. – PoloHoleSet Jun 02 '17 at 15:47
  • @PoloHoleSet My point was that criticising models isn't denying warming (though many react as though it is). Complex models (not just climate models) make people overconfident about uncertain predictions. And that overconfidence doesn't help win arguments about what to do about climate change. Also, model problems are not primarily caused because their inputs about CO2 are wrong. – matt_black Jun 02 '17 at 15:51
  • @PoloHoleSet "models have under predicted" that needs a reference or lots of references. It certainly ins't true for temperature. – matt_black Jun 02 '17 at 15:52
  • @matt_black - super duper, if I had somehow specified just temperature. if the temperature change is slightly less, but all the expected effects of that change are as bad or worse (loss of glaciers and ice caps, specifically, are the first things that come to mind), then, really, who the hell cares about the exact temperature? The effects of the temperature rise is what matters. I don't need any references for comments, actually. Feel free to google "climate change exceed model predictions" if you must have reading material to reference. – PoloHoleSet Jun 02 '17 at 17:16
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    @matt_black wrote "Complex models (not just climate models) make people overconfident about uncertain predictions." this comment is suggestive of a lack of familiarity with what climate models actually show. The spread of the model runs from climate models is quite broad (and understood to be an underestimate of the true uncertainty). The point is that action on climate change is justifiable even taking that uncertainty into account. If you want a very clear example of models under-estimating climate change, try arctic sea ice extent (http://www.realclimate.org/images/seaice10.jpg). –  Jun 02 '17 at 18:13