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Joseph E. Postma and the Greenhouse Effect Part 2

Posted on 17 August 2011 by Chris Colose

In part 1, Joseph E. Postma did not like the use of uniform solar absorption over the planetary sphere.  It was discussed that this is mainly just a bash against simple models which everyone knows is not how Earth works, but nonetheless gives useful answers.  Postma goes well beyond this however, and then proceeds to really show that he does not understand the very model he is complaining about, or much else about atmospheric physics. 

Venus is More Optically Thick Than a One Layer Model Can Give You

Postma starts by using Venus as a template for where the greenhouse model he is using breaks down.  And indeed, he is right.  His argument is that f (the emissivity) cannot possibly be greater than 1 (which is correct), and yet it must be in order to produce the Venus surface temperature in his Equation 29)  Based on this, he then states that the standard greenhouse model does not work in general.  The problem is that his Equation 29 assumes a one-layer atmosphere, which is an absurd assumption when you approach the extremely high optical thickness of Venus. Venus has a 90 bar atmosphere that has well over 90% carbon dioxide, some water vapor, and a greenhouse effect generated by suluric acid droplets and SO2.  The radiative transfer on Venus works much differently than on Earth, owing in part to intense collisional broadening of CO2 molecules.  A photon has an extremely difficult time escaping Venus, unable to do so until it reaches the very outer parts of its atmosphere.

Using the layer model, you would need many atmospheric layers to produce something close to Venus; with enough layers you would find that you could produce the surface temperature of Venus without violating conservation of energy.  With just one perfect absorbing atmospheric layer, the surface temperature cannot exceed 21/4 times the emission temperature (Te=~230 K on Venus).  But with two perfectly absorbing atmospheric layers, it can rise to 31/4Te.  With three layers, the maximum temperature is 41/4Te, and so on.  The reason the surface temperature is capped in this way is because the atmosphere itself must be emitting radiation and heats up when it absorbs photons from the surface, which in turn increases emission.  If the atmospheric layer were instead a good infrared reflector (i.e., it has a high thermal albedo), then you could delay heat loss to space that way and increase the surface temperature well beyond this value.  This could happen with CO2 clouds instead of H2O clouds, the latter are much more effective IR absorbers than IR scatterers, whereas the former could raise the IR albedo.

In essence, Postma stretches a simplified model to areas that it was never designed to go to, and then declares that its failure to work means the whole paradigm of the greenhouse effect is wrong.  The incompetence is overwhelming.  Postma is not done though, and decides to dig in further.  His next argument is amusing, but perhaps a bit strange to follow, so I will try to explain.

Lapse Rate Confusion

He claims that observations of the atmospheric lapse rate (the rate at which temperature declines with height) disallow the greenhouse effect.  His reasoning is that the atmosphere is at a fixed height.  When greenhouse gases warm the surface, and cool the upper atmosphere, that height still remains fixed, but obviously the temperature difference between the bottom and top of the atmosphere must increase.  Postma then claims that this necessarily implies that the lapse rate must have a greater slope than the theoretical value that he derived of about -10 K per kilometer (which is about right for a dry air parcel ascending).  That is, if the atmospheric height remains fixed, and the temperature difference between bottom and top is increased, then the rate at which air cools with height must increase.  Since this is not observed, then we have a problem, right?

In actuality, the atmospheric height is a distraction.  The adiabatic lapse rate does not extend beyond the point where convection breaks down, which is the tropopause.  The whole point of the greenhouse effect is that increasing atmospheric greenhouse gases does increase the “average” height at which emission to space takes place (and the tropopause increases in height too), so one IS allowed to extrapolate further down the adiabat to reach a higher surface temperature.  On Venus, the optical thickness forces the tropopause to some 60 km altitude. Additionally, it is worth pointing out that greenhouse gases warm the upper troposphere, not cool it, but they do cool the stratosphere.


Figure 1: Qualitative schematic of the old (blue) and new (e.g., after CO2 increase) temperature with height in a dry atmosphere.  Moisture tends to enhance the tropical upper atmosphere warming relative to surface.  Temperature increases to the right. 

TOA vs. Surface

Perhaps just as crucial to all of this, Postma cannot get around the surface energy budget fallacy, which says that increased CO2 causes surface warming by just increasing the downward infrared flux to the surface.  This problem is described in standard treatments of the greenhouse effect, which he does not seem to know exist, such as in Ray Pierrehumbert’s recent textbook. The primacy of the top of the atmosphere budget, rather than the surface energy budget, has been known at least since the work of Manabe in the 1960s (see also Miller, 2011 submitted)

In reality, the top of the atmosphere budget controls the surface temperature even more than the surface forcing, because the atmosphere itself is adjusting its outgoing radiation to space (and much of the radiation to space is originating in the upper atmosphere, owing to its IR opacity). Where the atmosphere is well-stirred by convection, the adjustment in temperature at this layer is communicated to the surface.  I described this in more detail here.  (As a side note, I hope people can bookmark the home page to that blog, which is run by a team of meteorologists, climatologists, and grad students in atmospheric science, at the University of Albany in NY, and we will be posting periodically on many different issues from ENSO to climate change to recent weather around the country).

Postma runs into this mistake again when he claims that the low water vapor in hot deserts is a problem for greenhouse theory, but this is largely due to the lack of evaporation cooling, which is just one component of the surface energy budget, and nearly absent in a desert.  This is one scenario where a detailed consideration of the surface budget is critical, as well as in other weakly coupled regimes.

The way CO2-induced warming really works in a well mixed atmosphere is by reducing the rate of infrared radiation loss to space.  Virtually all of the surface fluxes, not just the radiative ones, should change in a warming climate, and act to keep the surface and overlying air temperature relatively similar.  The back-radiation will indeed increase in part because of more CO2 and water vapor, but also simply because the atmosphere is now at a higher temperature. But if the lower atmosphere was already filled with water vapor or clouds to the point where it emitted like a blackbody (at its temperature), increasing CO2 would not directly increase downward emission before temperature adjustment, but would nonetheless warm the planet by throwing the TOA energy budget out of whack.


In summary, Joseph Postma published an article criticizing a very simple model that nonetheless produces useful results.  He made several very simple errors along the way, none of which are very technical in nature.  More sophisticated models are obviously designed to handle the uneven distribution of solar heating (which is why we have weather!); nonetheless, the educational tools are useful for their purpose, and in no way does Postma undermine the existence or necessity of the greenhouse effect.  Without a greenhouse effect, multiple studies have shown that the Earth collapses into a frozen iceball (Pierrehumbert et al., 2007; Voigt and Marotzke 2009, Lacis et al 2010) and indeed, after an ice-albedo feedback, plummets below the modern effective temperature of 255 K.  This work makes extraordinary claims and yet no effort was made to put it in a real climate science journal, since it was never intended to educate climate scientists or improve the field; it is a sham, intended only to confuse casual readers and provide a citation on blogs.  The author should be ashamed.

These posts comprise the Advanced rebuttal to Postma disproved the greenhouse effect.

The short URL for this rebuttal is

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Comments 1 to 13:

  1. Chris, I am going to disagree with your next to last sentence. Yes, it is wrong, but I am not sure it was intended to confuse casual readers. Let's accept the possibility that Joseph E. Postma simply does not have the intellectual ability to really understand what he is doing. The stupid, it sometimes hurts, but it really exists (I could show you a paper in which essentially nothing is right, most of which the author did not understand when I pointed it out (it actually got published in an otherwise reasonable journal (IF 2.8)).

    We'll have to live with people who seriously and honestly believe they are right, regardless of everything and everyone pointing out their errors. Their intentions may not be nefarious, they are just spectacularly wrong.
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  2. I am open to that possibility...but Joe Postma is now posting comments on Judith Curry´s blog, and the quality of the comments are slowly making me a skeptic, or perhaps even a ¨denier¨ of that possibility.
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  3. The pro-pollutionist camp produces an endless supply of fractured science arguments. Co-incidentally with Postma squeezing strawman and quadratic equations into one package, the Galileo Group is running a parallel diversion. They've revived the nonsense about 'CO2 is not a Greenhouse Gas'. That got Sciam's attention:

    Ever notice how Science wins every battle, and still loses the war?
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    Moderator Response: [Sph] Converted inline link.
  4. Briefly glancing over the paper, i am reminded of a pasty fat nerdy-looking boy i once worked with who's parents likened him to the next Einstein. He had a remarkable gift for stringing together esoteric verbiage in his observations that dumbfounded a lot of the doctors in the facility.

    When they decided to test the child's actual aptitude they were surprised to find he scored quite low. And not to be a jerk but i saw that coming a mile away. The poor child was trying to use a false image of intellect to compensate for what had to be a horrible self-image in all other respects.

    The gimmick was people's verbal comprehension couldn't follow the onslaught of vocabulary words to recognize that he was really just spouting gibberish. His words could be strung together in a verb-follows-noun grammatical sense but they were never actually articulating any sort of logical point. He'd just kind of spout nonsense and act like he was operating at a level of sophistication mere mortals couldn't ever hope to understand and no one was the wiser. But ask him to solve a simple logic or math problem and he wasn't going to get anywhere.

    Point is, this guy MIGHT just be pulling a similar stunt. He jumps on known approximations for being flawed because well, they're approximations, then sticks in other concepts that seem so esoteric but don't actually apply, all the while throwing dense technical words together that don't actually add up to anything then foams at the mouth about violating laws of thermal dynamics. The guy is a [-snip-] trying to pass himself off as an emerging world authority who's exposed that everyone else is wrong.
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  5. I am wondering if it was worth the time to do this. Joseph Postma has now been pretty much laughed out of Judith Curry´s blog post on it, and with the crowd she gets, that is saying something...
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  6. You summed it up well. “The incompetence is overwhelming.”
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  7. Way, way of topic, but I don't know where else to post: I read in the current issue of Discover that a scientist has developed a method of pulling the carbon out of the air using only a small amount of PV and a lot of solar thermal. He ends up with either carbon monoxide or solid carbon. It was presented as a feasible solution to global warming. Am I missing something?
    Here is the article:
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  8. Sorry, Chris, I just see more evidence he is one of those "Bozo the Clown"-Galileos. I really think he honestly thinks he is right. Problem is, no one can show him wrong, because he won't accept being wrong. He's right, period. He's Galileo!
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  9. From Idiot Tracker

    "For months "Climate Etc" has been plagued by thousands upon thousands of comments triggered by her efforts to debunk some obvious denier fallacies about the greenhouse effect, which she has collectively labelled a "greenhouse dragon." Presently Judith's lead is a rather mundanely titled effort: "Postma on the greenhouse effect."

    "But I rather like what must be her original title... ..."A slain greenhouse dragon"."

    Her introduction mentions this Skeptical Science blogpost.
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  10. I've gotten the impression that there is a class of people I call symbol manipulators. Basically, these are reasonably intelligent people who have a hard time knowing when the equations apply to the physical world and when they don't, or when they apply, but only as an approximation. They can be pretty good at juggling math equations and laws of nature, but there is a disconnect between the symbols and what they mean in the real world. I'm getting the impression that Postma might fall in this category.

    An extreme example: There was a fellow engineering student I knew who read something to the effect that no matter exists at absolute zero. All the rest of us took that to mean the entropy and the diffusion of energy guaranteed that all matter had some, possibly very minute, amount of heat energy (molecular motion). He took it to mean that, if you could somehow reduce matter to a temperature of absolute zero, it would cease to exist. He wasn't a bad person, and he was capable of producing language and formulas that were consistent with most laws of physics, but he was missing a connection with reality at a fundamental level.

    It might be that Postma would benefit from an explanation of how the composition, the density, and the temperature of the atmosphere vary with altitude, and why that is, because that is where simple atmospheric models suffer a disconnect with reality. Then again, that is knowledge that is readily available; so, he has probably been exposed to it before.

    Is this pattern a Dunning-Kruger effect, a result of cognitive dissonance, or something else? I don't know.
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  11. 5, Chris Colose,

    It is certainly worth at least some effort, just to have a record of it. It serves three purposes:

    1) For a handful of deniers who believe this stuff, there's a chance they'll actually behave skeptically long enough to find your post, read it, and maybe put Postma aside in hopes of a more believable excuse for their denial.

    2) For people on the fence, or in denial but able to understand the truth when they see it, you are providing a resource which will help them to not only move on past Postma's gibberish should they stumble into it, but also to see how easily the unwary can be confused by high-faloot'n sounding gobbledygook.

    3) It will provide a log of yet another example of denial Climastrology, a growing and fantastic branch of alchemy that, if it grows large enough, will eventually serve as a huge, blinking neon sign for everyone to look at when considering how inane not only Postma's but almost all other denial arguments on the table really are.

    The sad fact is that a huge, huge number of deniers are Dunning-Kruger victims of the ilk of Postma (many can be found posting ridiculous comments on this very site). Not all (but many) are able to put together a web page or PDF of complex and therefore seemingly plausible gibberish. They are the poster children for those many more who don't or can't go that far, but also think they know better than everyone else because they rose in the ranks of their chosen but narrow field of engineering or science, and were able to solve any problem with their one hammer of choice.

    Because of the air-play that Postma is getting, his nonsense needs to be thoroughly debunked.
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  12. I guess I really thought that trying to appeal to Postma from an astrophysical point of view would help him see his error. What's interesting about it is that my own background in stellar atmospheres led my intuition astray too. The difference is that when I saw that my intuitive view of how nature works conflicts with every non-loony authority, my response was to step back and try to figure out where I went wrong. And it didn't take long to find the mistake. Just like grad school all over again...

    I've apparently greatly underestimated the blinders on these latter-day Galileos. The most depressing part of it is that the only long-term result is likely to be that this 'dramatic new theory' will become a permanent talking point for the right-wing nuts. If I have to pick sides (and from my interactions on that site, apparently I do) put me on the science team, please.
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  13. The thing about siding with Science is that it will sometimes lead you to conclusions that you find non-intuitive and difficult to accept. Siding with Fantasy will lead you anywhere you wish it to, except to reality.
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