The indelible dumbness of physicists
Eli has always been impressed by Myanna Lahsen's take on physicists
they think they know everything, because they’re smart. What they don’t understand is that yes, it is true, actually meteorology is a branch of physics. And so you take a physicist, like me, and you can sit him down, and in 2 or 3 years, they could learn meteorology. But physicists confuse being smart and having the ability to learn everything with actually knowing stuff!and by way Watts, excerpted by Tallbloke, via a comment at Open Mind, comes another example, one Robert Brown, PhD, at Duke who offers up a BOE to showcase another argument from personal incredulity.
As some noble prize winners, he gets the wrong answer for the right reason. We have all gone through the trivial exercise of balancing the solar input against radiative loss from an Earth without an atmosphere, which shows that without greenhouse gases the temperature of the Earth would be a uniform 255 K, about 33 K colder than it is on average. Brown asks what would happen if the surface temperature was not uniform, without realizing that Arthur Smith provided the answer, it would be a lot colder. If you account for day/night differences, the change of temperature with latitude and such, 33K is a lower limit for the greenhouse effect if you insist on radiative balance. To cut a long story there short, assumption of a uniform surface temperature UNDERESTIMATES the effect of greenhouse gases on surface temperature. To return to the first paragraph, DECREASING the temperature at which the Earth's atmosphere radiates to space by increasing greenhouse gases, requires that the surface temperature INCREASE in order to restore radiative balance. Brown clearly was not on the distribution list.
The point is that as temperatures increase, the rate at which the Earth loses heat goes strictly up, all things being equal. Hot bodies lose heat (to radiation) much faster than cold bodies due to Stefan-Boltzmann’s T^4 straight up; then anything that increases the inhomogeneity of the temperature distribution around the (increased) mean tends to increase it further still. Note well that the former scales like:
P' being the radiated power.P’/P = 1 + 4 dT/T + …
straight up! (This assumes T’ = T + dT, with dT << T the warming.)
At the high end of the IPCC doom scale, a temperature increase of 5.6C is 5.6/280 \approx 0.02. That increases the rate of Stefan-Boltzmann radiative power loss by a factor of 0.08 or nearly 10%. I would argue that this is absurd — there is basically no way in hell doubling CO_2 (to a concentration that is still < 0.1%) is going to alter the radiative energy balance of the Earth by 10%.Well, Eli leaves it to the reader to decide whether a 6 K temperature change is reasonable for CO2, greenhouse forcing doubling, without getting into the issue of why Brown chooses 6K rather than the generally agreed on 2-3 K (so that is only a 2- 3% change), please don't spit the cherry pits out on the linoleum or the window, this is a high class blog, but even without going much further, how unreasonable is that 2-3 K change if the greenhouse effect accounts for more than 33 K of surface warming, which it does. Still dear bunnies, there is more.
The statement that "The point is that as temperatures increase, the rate at which the Earth loses heat goes strictly up, all things being equal." is where the good Doctor Brown goes serious GIGO. It is correct that the rate at which the Earth's SURFACE loses heat goes strictly up, but the surface is NOT where most of the thermal IR is emitted to space.
That is rather high up in the atmosphere, which can be seen by comparing the emission to space with the Planck distribution of thermal emission from the surface for example, but there are plenty of accurate measurements and models.
The point at which the emission curve matches a blackbody curve tells you the temperature of the effective altitude at which emission is occurring to space. Raising the greenhouse gas concentration raises the level at which the emission to space occurs to a colder level, and thus one where emission is slower. To make up for that the surface has to warm in order to push more energy through the open window directly into space.Pass the mole hammer please.
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39 comments:
Where this whole discussion started is a thread at WUWT where everyone is trying to defend the latest piece of total nonsense, a "Unified Theory of Climate" that is being embraced by people like Tallbloke even though it manifestly violates conservation of energy http://wattsupwiththat.com/2011/12/29/unified-theory-of-climate and is riddled with other boneheaded errors!
They are evidently trying to revive Steve Goddard's "atmospheric pressure is responsible for planetary warming" hooha. They look a little more sophisticated than Goddard*--not hard--but trying to apply the ideal gas law over the range of temperatures, pressures and atmospheres they do seems just a tad gormless to this musician. (Though my intuition says the abuse of the IGL is more fundamental than that.)
It's also marked by the same inherent self-contradictions: pressure "isn't energy," they say, but still it boosts planetary temperatures by some mathematically indeterminate mechanism--without, of course, adding energy. . .
Call it the 'dumbness of forest scientists/remote sensing experts.'
*Not that I'm claiming any sophistication in these matters for myself, mind you. . .
Eli, could you rephrase
> To make up for that the surface has to warm in order to push
to eliminate the suggestion of teleology?
I know what you're saying, but I couldn't explain it to a fifth grader (my criterion for being of some use to the world). I can't come up with an analogy or poet's physics explanation of how that works.
Teleology is a slippery slope; look at this guy who claims that plants put stomata on the underside of their leaves because the heavy CO2 stays closer to the ground, and, well, other stuff ... /unified-theory-of-climate/#comment-847454 has
Hey, I have it on good authority that no climate scientists know this stuff at all!
The second he said that, I knew it was HS, stable staple, the rest of the way down.
It must be something in the water
"Raising the greenhouse gas concentration raises the level at which the emission to space occurs to a colder level, and thus one where emission is slower...."
That bit needs to be repeated more often - I don't think there's a general appreciation of it among the laity.
"Teleology is a slippery slope; look at this guy who claims that plants put stomata on the underside of their leaves because the heavy CO2 stays closer to the ground"
What, teleology used to explain a biological adaptation? Such a thing is too ludicrous to even consider! ;)
As for the reason that stomates are only on leaf undersides, there are some minor nitpicks one might raise. Such as the fact that it's not true in certain plant groups of minor importance, such as many forbs and most or all of the major grain crops, or the fact that there is no clear "underside" on e.g. the pines and spruces that dominate many millions of hectares of NH conifer forest. Other than that, seems like a pretty solid idea.
"look at this guy who claims that plants put stomata on the underside of their leaves because the heavy CO2 stays closer to the ground."
Apart from the minor points that stomata allow gaseous exchange in both directions (not simply for CO2 uptake) and in doing so lose water. Putting organs that leak water on the top of leaves doesn't seem especially sensible, but hey let's not let well established biological concepts get in the way of an ideological rant.
The AnonyBilby
Water is exchanged as vapor - not liquid. Gravity and therefore location is irrelevant.
and I guess Tallbloke is not taking any "erudite lesson" from Eli.
Looks like another mole truncheon is in order.
Hey, I notice a lot of stupidity coming from non-physicists too, and even from atmospheric physicists.
Your friendly ignorant but arrogant physicist,
AKA, CIP
The Brown argument makes a complete dogs breakfast of the way CO2 affects the energy balance, of course, but in your rebuttal, you need to be a bit more careful to state precisely what problem you are solving when you quote the temperature of the Earth "without an atmosphere." Even leaving aside the effect of the ocean freezing and increasing the albedo, if you took away the atmosphere you'd also take away the atmospheric heat transport which keeps the surface temperature relative uniform (the surface temperature only varies on the order of 10% about the mean for the actual Earth). If you took away the atmosphere and if the Earth had a rocky surface like Mars or the Moon, the surface temperature distribution would look very much like the Moon -- about 100C at the subsolar point where it's noon, and maybe -100C on the night side depending on what kind of rock we're talking about and its diffusion constant. The rapid rotation of the Earth doesn't lead to huge differences from the Moon, because of the low thermal inertia of rock. So, the surface of the Earth "without an atmosphere" would be nothing like a uniform 255K. To get that, you don't want an Earth without an atmosphere, but rather an Earth with an IR-transparent atmosphere (like nitrogen) which would keep the surface temperature more uniform, though still not completely isothermal. Even then, you really have to take away the ocean, too, since the ocean would put water vapor and clouds into the atmosphere, violating our no-greenhouse assumption; and besides that, as I said, the ocean would freeze over if you took away the greenhouse effect, and it would then be a lot colder than 255K because of the high albedo of ice.
And even if you take away the ocean and put in a thick N2 atmosphere, you're still not really there, since the 255K comes from the absorbed solar radiation including effects of clouds, which we are taking away. So you have to paint your rock grey enough that the planet still has the same albedo as the original Earth.
For all these reasons, I never really liked the "255K no-atmosphere" sound bite. To get 255K you have to do something really contrived. If you take away the Earth's atmosphere, what you basically get is a big moon. Atmospheres do a lot of things besides just give you a greenhouse effect.
None of that makes any of Brown's points valid, though. Eli's critique of where Brown goes wrong is pretty much spot-on. The fact that you need to use radiating temperature, not surface temperature, to determine climate sensitivity is pretty much textbook stuff (and need I mention Principles of Planetary Climate here:)
--Raypierre
> Raising the greenhouse gas concentration
> raises the level at which the emission to space occurs
Is a Galton Board a useful poetic approximation of how photons scatter in the atmosphere? (photons and greenhouse gases instead of ping pong balls and wooden pegs; only the ball that ends up with no outside neighbor/no peg to intercept it can travel off the board).
Add more pegs and balls, and you make the normal curve bigger -- and with more pegs the "last ball on the outside edge" has to be further away so it can escape.
Nah. But some kind of mental image/exercise/analogy's needed.
That pushes the extreme out further....
Eli,
I suggest a new and improved title for this section:
"The incredible dumbness of SOME physicists"
After all, Michael Mann and James Hansen are physicists by training. Raymond Pierrehumbert, author of the textbook Principles of Planetary Climate*, received his BA in physics at Harvard.
In the interests of full disclosure, I admit being a physicist.
BTW Eli is under intense suspicion of being a chemist, and chemists gave us cold fusion. So there.
*the publisher claims the textbook is suitable for advanced undergraduate students. They damn well better be VERY advanced students.
-John
John --- I agree with your footnote but recall Raymond teaches @ U. Chicago.
"Raising the greenhouse gas concentration raises the level at which the emission to space occurs to a colder level, and thus one where emission is slower."
Although I haven't calculated it myself, I've seen estimates that the distance is of the order of 180m increase since 1900. I wonder what the thermal expansion of the atmosphere below the tropoause caused by the ~0.7C increase in lower tropospheric temperature would do in terms of raising the tropopause. If it was around the same 180m wouldn't that mean the temperature at the point where the max radiative emission to space was occurring would still be about the same? Another question I have is what the effect of a 30% reduction of the size of the thermosphere since the Sun went quiet in 2005 might have on the height of the tropopause? No-one seems to know.
Regarding Joel Shore's comment:
Nikolov and Zeller's conference poster is correct, if somewhat elliptical due to space limitation. I corrected Joel's misinterpretation of an energy redistribution due to higher near surface pressure as a failure of energy conservation, but to no avail it seems. As Nikolov points out on my blog It's rather astonishing that a lot of the climate community on the warm side of the debate only seem to remember the radiative properties of gases from their atmospheric science classes and nothing of the gas laws and how they operate in a gravitational field.
Cheers
TB
> "Raising the greenhouse gas concentration raises the level at which the
> emission to space occurs to a colder level, and thus one where emission is
> slower."
> Although I haven't calculated it myself, I've seen estimates that the distance
> is of the order of 180m increase since 1900.
Not likely... the right number is one (2-folding) scale height per doubling, i.e., about 5 km. Since 1900 we've seen half a doubling, so, say, 2500 m.
http://en.wikipedia.org/wiki/Scale_height
This is of course only for the part of the spectrum where the atmosphere is opaque, i.e., the part where the atmosphere, not the surface, is doing the radiating. And I'm leaving H2O out of the story which is complicated enough already ;-)
Another "the whole climate community is wrong" claim. There seem to be a lot of Galileos out there, but they all give a different reason. Very confusing. Reminds me of that line from the song "Two men say they are Jesus, one of them must be wrong".
Anon(1).
>> they think they know everything ...
not only do physicists know everything - they know everything better 8-)
raypierre,
One nit. N2 is not completely IR transparent because of collision induced continuum absorption that would peak around 100 cm-1. This absorption is swamped for vertical paths by water vapor, but becomes significant for paths through the limb of the atmosphere at very high altitudes. I think CIA is insignificant for monatomic gases, so an argon or neon atmosphere might be considered perfectly transparent.
There was a long discussion at Science of Doom about the temperature profile of a perfectly transparent planetary atmosphere. My conclusion was that there would be some lapse rate caused by circulation due to the the latitudinal temperature gradient (assuming a non-superconducting surface) inducing a latitudinal pressure gradient. Without atmospheric radiative cooling, though, I don't think the lapse rate would reach the adiabatic rate.
Martin Vermeer,
"Not likely... the right number is one (2-folding) scale height per doubling, i.e., about 5 km. Since 1900 we've seen half a doubling, so, say, 2500 m."
Let's see, for the US 1976 standard atmosphere, the lapse rate is 6.5 K/km so according to your logic, the surface temperature should have gone up over 16 K. Even 180m is too much. 5 km/doubling is too much even for the center of the CO2 band. Using MODTRAN, the optical density for CO2 absorption at 668 cm-1 (peak absorption in the MODTRAN output) at 280 ppmv CO2 is 33 km. That increases to 36 km at 560 ppmv. Averaging over 630-710 cm-1 the altitudes are 16.6 km and 18.8. Oh, and the scale height for the dry atmosphere is 8 km, not 5 km. For water vapor, it's about 2 km.
Oops, 8 km is the e-folding height.
DeWitt, what you're overlooking is what I pointed out, that the atmosphere is opaque only for a small part of the spectrum. Looking at Eli's picture I would say the 15 micron band occupies about 10%.
10% of 16 degrees is 1.6 degrees... in the ball park for the dry CO2 doubling sensitivity.
DeWitt, I know all about the N2 continuum (it's in Chapter 4, based on Courtin's data, and important for Titan). But for Earthlike conditions with a bar or so of N2, it's transparent enough that it serves for the purpose of the example, especially in view of the fact that the part of the spectrum where N2 absorbs well by CIA is at longer wavelengths than the dominant emission of a warm planet like Earth (vs 100K for Titan). If you wanted something that was even more transparent, you could go to a pure He or Ar atmosphere, I suppose.
We've done some simulations of IR-transparent atmospheres for tide-locked planets, but they're not published yet. You do establish an adiabat due to surface-driven convection (remember turbulent heat exchange) but the whole atmosphere fills up with the potential temperature determined by the hottest spot on the planet. Earlier, we published some simulations in a similar spirit for the Hadley cell in the transparent limit, in QJRMS.
--raypierre
Raypierre, in attempting to resolve the N2 IR transparency nitpick by suggesting a pure He atmosphere, do you not fall foul of the greater nitpick that your new atmosphere would not be gravitationally bound to the Earth, rendering all other considerations moot?
--njp
Dr. Jay Cadbury, phd.
"how unreasonable is that 2-3 K change if the greenhouse effect accounts for more than 33 K of surface warming, which it does. Still dear bunnies, there is more."
Sorry Eli, this is nothing more than an opinion. You can't test it, therefore you can't prove it. Cue furious rage from Caerbannog.
NJP-- The lifetime of an He atmosphere on Earth would be long enough that the climate would reach equilibrium, especially since we have to take away the ocean to get rid of ice-albedo feedback and the water vapor greenhouse effect. But if you want a longer-lived atmosphere, you could always use argon instead. Both atmospheres are implausible from a standpoint of elemental abundance and physics of planet assembly, but it's just a thought experiment anyway. And note that even monotomic gases are not COMPLETELY transparent to IR, though much more so than diatomic gases.
Regarding Anonymous 5/1/12 7:25 AM: Note that the "33K colder without greenhouse effect" sound bite is not in any event the basis for the prediction of the amount of warming you get from doubling CO2. That comes from lab spectroscopy data backed up by atmospheric observations, plus simulations of basic atmospheric physics verified to one extent or another against data (very well checked for water vapor feedback, more uncertainty for cloud feedback). The "33K" meme isn't even an observational check of how well we understand the physics, since that state of the Earth has never been observed and would be hard to contrive; it's only an attempt to put the greenhouse effect in perspective (very large for Venus, moderately large for Earth, absent for the Moon). It's an attempt at scientific communication, not the basis of any prediction itself. I myself don't think it's a particularly successful or useful attempt. If you want a good indication of how well we know the basic physics of the greenhouse effect, it's better to look at the Earth/Mars/Venus comparison, which allows actual observations. That's done (in the spirit of scientific communication) in my Physics Today article.
--Raypierre
And having tested and multiply proven it, Cadbury will refuse to admit it. It so very much an inconvenient truth, and it seems that cranks willing to believe bullshit will ever be with us.
Foo. Use the average temprature of the lunar surface. That's sufficient to make the point that the so-called greenhouse effect is real.
I've often been accused of physicist partisanship in the physics/engineering flame wars. I do think the # of physicists who are science deniers is quite low. Even most of the crank physics out there is the work of xxx engineers. In my rough estimation the crankism and science denial goes roughly engineers, mining geologists, computer programmers, everyone else.
An anonymouse wrote "Reminds me of that line from the song 'Two men say they are Jesus, one of them must be wrong'."
How appropos - the song is "Industrial Disease" by Dire Straits ... and global warming certainly qualifies as an industrial disease that could lead to dire ... ok enough word play.
tallbloke said: "I corrected Joel's misinterpretation of an energy redistribution due to higher near surface pressure as a failure of energy conservation, but to no avail it seems."
I understand that one can have different temperature distributions that give different surface power emitted...but there ain't any way you are going to have ~390 W/m^2 emitted from the surface with only 240 W/m^2 absorbed by the Earth-atmosphere system unless some of that emission is absorbed by the atmosphere. 255 K is the maximum temperature a blackbody emitter can have with ANY temperature distribution...and the Earth's surface is pretty close to a blackbody over the relevant wavelengths.
Even skeptics like Willis Eschenbach and Roy Spencer understand this and are desperately trying to get you guys to stop making fools of yourselves by endorsing this nonsense.
"As Nikolov points out on my blog It's rather astonishing that a lot of the climate community on the warm side of the debate only seem to remember the radiative properties of gases from their atmospheric science classes and nothing of the gas laws and how they operate in a gravitational field."
What is astonishing is how profoundly ignorant Nikolov is not only of climate science but what climate scientists do and do not know! In the comment of his that you linked to, we see a perfect example of that. He gives the impression that climate scientists ignore the important role of evaporation as a heat transport process, which is hogwash.
Perhaps it is simply meant to distract the naive from the fact that the way that he and Zeller put convection into the simple radiative model that they started with was, by their own admission, so that it drives the temperatures T_a and T_s to be equal. So, what they have demonstrated is what anyone who has read a textbook like Ray Pierrehumbert's on climate science already knows: that to get a greenhouse effect, you need a lapse rate! Too bad we live in a universe where convection only drives the lapse rate down to the adiabatic lapse rate.
Just as a postscript on the above, tallbloke has now decided to censor me on his blog for arguing a point so uncontroversial that even Willis Eschenbach and Roy Spencer agree on it. Check it out: http://scienceblogs.com/deltoid/2012/01/january_2012_open_thread.php#comment-6208696
How does this fit in with the dumbness of physicists:
http://www.scirp.org/journal/PaperInformation.aspx?paperID=9233
Kramm rambling again, so beware!
Marco
Marco:
Hmmm..."Natural Science", apparently another journal to scratch off the "real scientific journals" list!
"Two men say they are Jesus, one of them must be wrong".
In this context (denialist crackpottery), I think that should be "at least one of them".
Thanks Eli, I linked to your blog post from a Climate Etc thread to knock some sense into the usual suspects.
http://judithcurry.com/2012/02/03/week-in-review-2312
NuclearBadger
I guess the Nikolov paper will find a good home in Energy & Environment.
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