Guest post By Ben Herman and Roger A. Pielke Sr.
During the past several months there have been various, unpublished studies circulating around the blogosphere and elsewhere claiming that the “greenhouse effect” cannot warm the Earth’s atmosphere. We would like to briefly explain the arguments that have been put forth and why they are incorrect. Two of the primary arguments that have been used are
- By virtue of the second law of Thermodynamics, heat cannot be transferred from a colder to a warmer body, and
- Since solar energy is the basic source of all energy on Earth, if we do not change the amount of solar energy absorbed, we cannot change the effective radiating temperature of the Earth.
Both of the above statements are certainly true, but as we will show, the so-called “greenhouse theory” does not violate either of these two statements. (we use quotation marks around the words “greenhouse theory” to indicate that while this terminology has been generally adopted to explain the predicted warming with the addition of absorbing gases into the atmosphere, the actual process is quite a bit different from how a greenhouse heats).
With regards to the violation of the second law, what actually happens when absorbing gases are added to the atmosphere is that the cooling is slowed down. Equilibrium with the incoming absorbed sunlight is maintained by the emission of infrared radiation to space. When absorbing gases are added to the atmosphere, more of emitted radiation from the ground is absorbed by the atmosphere. This results in increased downward radiation toward the surface, so that the rate of escape of IR radiation to space is decreased, i.e., the rate of infrared cooling is decreased. This results in warming of the lower atmosphere and thus the second law is not violated. Thus, the warming is a result of decreased cooling rates.
Going to the second statement above, it is true that in equilibrium, if the amount of solar energy absorbed is not changed, then the amount of IR energy escaping out of the top of the atmosphere also cannot change. Therefore the effective radiating temperature of the atmosphere cannot change. But, the effective radiating temperature of the atmosphere is different from the vertical profile of temperature in the atmosphere. The effective radiating temperature is that T that will give the proper value of upward IR radiation at the top of the atmosphere such that it equals the solar radiation absorbed by the Earth-atmosphere system.
In other words, it is the temperature such that 4 pi x Sigma T4 equals pi Re2 Fso, where Re is the Earth’s radius, and Fso is the solar constant. Now, when we add more CO2, the absorption per unit distance increases, and this warms the atmosphere. But the increased absorption also means that less radiation from lower, warmer levels of the atmosphere can escape to space. Thus, more of the escaping IR radiation originates from higher, cooler levels of the atmosphere. Thus, the same effective radiating temperature can exist, but the atmospheric column has warmed.
These arguments, of course, do not take into account feedbacks which will kick in as soon as a warming (or cooling) begins.
The bottom line here is that when you add IR absorbing gases to the atmosphere, you slow down the loss of energy from the ground and the ground must warm up. The rest of the processes, including convection, conduction, feedbacks, etc. are too complicated to discuss here and are not completely understood anyway. But the radiational forcing due to the addition of greenhouse gases must result in a warming contribution to the atmosphere. By itself, this will not result in a change of the effective radiation temperature of the atmosphere, but it will result in changes in the vertical profile of temperature.
The so-called “greenhouse effect” is real. The question is how much will this effect be, and this is not a simple question. There are also questions being raised as to the very sign of some of the larger feedbacks to add to the confusion. Our purpose here was to merely point out that the addition of absorbing gases into the atmosphere must result in warming, contrary to some research currently circulating that says to the contrary.
For those that might still question this conclusion, consider taking away the atmosphere from the Earth, but change nothing else, i.e., keep the solar albedo the same (the lack of clouds would of course change this), and calculate the equilibrium temperature of the Earth’s surface. If you’ve done your arithmetic correctly, you should have come up with something like 255 K. But with the atmosphere, it is about 288 K, 33 degrees warmer. This is the greenhouse effect of the atmosphere.
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Dave Springer says:
Theory is built from experiment. In the case of the theory of radiative transfer, we have not only tons and tons of experimental work but now a lot of technology built upon theory. And, this is true even for radiative transfer specifically in the atmosphere. How do you think the whole field of satellite remote sensing works? It seems rather strange that you doubt the theory of radiative transfer when applied to understand the greenhouse effect and yet you don’t doubt the satellite measurements of tropospheric temperatures that rely on that same theory. I think part of this whole reaction to AGW is an interesting psychological study of how people will believe what they want to believe and endlessly question and demand evidence to prove what they don’t want to believe.
If you want to do yet another experiment to test things that are already well understood, be my guest.
tallbloke and Nasif, we need you out there in [snip] land putting a stop to all this nonsense.
cbs‘s post gives the Stefan formula that should apply to a body that is not in vacuum, and Nasif has it in his post .
Any body who has followed a physics program knows about boundary value problems, having solved a number of them in various courses. It is evident that when one has more than one body the solution has to take into account the existence of this body whether it is in fluid flow or electrostatics. It has no meaning to ask questions like ” does the photon know”, in some frameworks, namely the wave electromagnetic ones, yes it does. ( and lets not enter into the quantum mechanical argument of entanglement) .
The Stefan formula for a body Tb and its surroundings Ts shows that in a different framework, and tells us if the surrounding are of the same type and at the same temperature there is no overall radiation.
Putting a second body in the problem of a body in vacuum ( simple Stefan law), is taking a delta(solid angle) of the surrounding and there will be the corresponding modification to radiation from the body under consideration. It has nothing to do with back scattering hand waving.
John Finn says:
July 26, 2010 at 3:39 pm
anna v says:
July 26, 2010 at 5:34 am
John Finn says:
July 26, 2010 at 2:25 am
anna v:You have once more described Peden’s oven, the paradoxical chicken that cooks by itself because of the reflected radiation:
John Finn:No I haven’t. The planet-atmosphere has an external heat source – it’s sun.
Back radiation hand waving does not use the sun in the problem.
Jim D says:
July 26, 2010 at 6:35 pm
Published work shows that a third of the downward longwave flux at the South Pole surface is from CO2. This paper goes into measurements of the spectrum to prove it. It is hard to dispute that level of detail.
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3525.1
from Abstract “About two-thirds of the clear-sky flux is due to water vapor, and one-third is due to CO2, both in summer and winter.”
Model is not a four letter word, but it tends to be treated like one in climate discussions.
So no, the discussion cannot stop because real life and data say otherwise.
Note , it is all models and modeling. even clear skies are modeled!
from your link :Clear-sky conditions are identified by
comparing radiance ratios of observed and simulated spectra.
“Jim D says:
July 26, 2010 at 6:35 pm
Published work shows that a third of the downward longwave flux at the South Pole surface is from CO2. This paper goes into measurements of the spectrum to prove it. It is hard to dispute that level of detail.
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3525.1
from Abstract “About two-thirds of the clear-sky flux is due to water vapor, and one-third is due to CO2, both in summer and winter.”
I had the impression that the air over the South Pole is exceedingly dry !!
Jim D says:
July 26, 2010 at 6:35 pm (Edit)
Published work shows that a third of the downward longwave flux at the South Pole surface is from CO2. This paper goes into measurements of the spectrum to prove it. It is hard to dispute that level of detail.
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3525.1
from Abstract “About two-thirds of the clear-sky flux is due to water vapor, and one-third is due to CO2, both in summer and winter.”
Can we move past this argument about CO2 being insignificant now?
On the contrary Jim, it reinforces the point. Antarctica gets about 8mm of snow per year, the rest just blows around. The air is incredibly dry. Antarctica is classed as a desert. So if co2 can only manage 33% of the radiative forcing there, it is a good demonstration of how insignificant compared to water vapour it really is.
Uber says:
July 26, 2010 at 7:56 pm (Edit)
tallbloke and Nasif, we need you out there in [snip] land putting a stop to all this nonsense.
We’re trying. You can help by spreading the word about this thread and this one on my blog:
http://tallbloke.wordpress.com/2010/07/27/nasif-nahle-nails-the-radiative-physics-of-co2
Jim D says:
July 26, 2010 at 6:35 pm
Published work shows that a third of the downward longwave flux at the South Pole surface is from CO2. This paper goes into measurements of the spectrum to prove it. It is hard to dispute that level of detail.
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3525.1
from Abstract “About two-thirds of the clear-sky flux is due to water vapor, and one-third is due to CO2, both in summer and winter.”
Can we move past this argument about CO2 being insignificant now?
Two things, Jim:
First, it’s ‘may’ we, and not ‘can’ we, unless you’re asking about abilities …
Next, if CO2 is a transmission medium for downward radiation, then by the fact of the gas being reciprocal in nature, would it not also be a transmission medium for upwards radiation?
Ergo, it it conveys upwards and downwards with equal ability, then what goes in, goes out just as fast.
Any questions?
Dave Springer says:
July 26, 2010 at 3:54 pm
[–snip for brevity–] CO2 doesn’t exist in a vacuum.
Oh? Really now? There’s no CO2 in space, anywhere? Got proof?
Dave Springer says:
July 26, 2010 at 3:54 pm
[–excerpted–]So the long and the short of it is that greenhouse warming is real, Co2 greenhouse warming is real, but CO2 probably makes no net contribution to global warming in the present or near future context and in no case is anthropogenic CO2 going to have any measurable effect. Possibly it becomes an important greenhouse gas in “snowball earth” episodes.
You do realize that you’ve contradicted yourself quite severely there, don’t you?
If —IF— CO2 is to be any agent of ‘CAGW/CCC,’ then it can’t be said to be involved in a “snowball Earth” scenario, as how could it cause a reverse effect?
Either it contributes to warming, or it contributes to cooling, according to one or another theory.
My theory says just this: It’s a reciprocal gas, which contributes —in total— nothing to the thermal character of the Earth’s temperature.
Wow. I read the entire paper. It’s littered with uncertainties, guesses, and admitted instrumentation error. The investigators were surprised by the constancy of the H2O/CO2 ratio (2:1) in downwelling LWIR across seasons when measured absolute humidity varied widely yet didn’t cause any variation in the flux ratio. The flux ratio appears to be bogus based on incorrect assumptions of first principles.
I’m given to understand there is some controversy over what the downwelling emissive irradiance spectra should look like. Absorption spectra are clearly understood where blackbody spectrum has big holes in it where different atoms and molecules absorb narrow bites out of it in different bands characteristic for those different atoms and molecules. The controversy appears in emissivity for those same atoms and molecules where the majority opinion seems to be that while absorption occurs in narraw characteristic bands emissivity occurs as blackbody radiation dependent only on temperature. Thus you can tell apart H2O and C02 absorption spectra you can’t tell apart H2O and CO2 emission spectra.
If the latter case is correct then the surprise in seeing no ratio change as the H20 content of the atmosphere changed is a simple one. What was presumed to be separate emissivity spectra was something else and the giveaway was that the ratio didn’t change when it should have according to the assumed first principles. The investigators labored long and hard to explain the discrepancy with all kinds of speculations rather than admit that the predictions of the hypothesis simply failed under experimental test. The scientific method demands the hypothesis be discarded when its predictions fail. In climate science the method seems to be that hypothesis is retained and the observations must be somehow incorrect. In this case the investigators placed the blame on inaccurate humidity measurements among other things. One might reasonably ask if something as simple as humidity isn’t being measured accurately how accurate are the much more difficult measurements involving radiative fluxes, ice particle content, clear sky vs. hazy sky, and other things like that, all of which were mentinoed as instrumentation uncertainties. The only thing they weren’t uncertain about was that their model had no flaws in it.
Bad science. FAIL.
I’ve observed this aberration in scientific method primaily in climate science and evolutionary biology. The aberation is where the theory is held with what can only be described as religious faith, and when observations do not agree with theoretical predictions, the observations must somehow be wrong.
Darwin predicted the fossil record would eventually be observed to show a continuum of small evolutionary changes that over time would add up to large phenotype variations characteristic of different taxonomical classifications. One hundred fifty more years of fossil digging and the fossil record was still one of sudden emergence of new species fully characteristic in phenotype, persistence for some period of time virtually unchanged, then sudden disappearance. Stephen J. Gould rather famously stated:
And thus rather than discard Darwin’s hypothesis of gradual evolution came up with a theory called punctuated equilibrium to explain the discrepancy which basically states that major evolutionary transitions occur in small isolated populations and that small numbers of individuals in isolated locations will tend to have very little relative representation in the fossil record. In other words the theory is correct so the observations must be wrong.
At least it can be said of Gould though that it didn’t take a whistleblower to get him to write of paleontology’s “trade secret” but that was only because he believed he had an explantion for it. He kept the secret until that time.
The frauds cited below were much worse:
I found the following explanation which appears to be succinct and correct regarding LWIR emission from the ground (or water), absorption and reemission from greenhouse gases:
“The IR is emitted from the surface of the earth as black body radiation, which has a wide bandwidth. Then CO2 absorbs a fingerprint set of frequencies, which is 8% of the available black body radiation. As it is absorbed, it is instantly converted into heat (in less than a pico second). The heat is distributed over all molecules in the atmosphere, which means 78% nitrogen and 21% oxygen. After some time, an equivalent amount of black body radiation is emitted from everything in the atmosphere, and 8% of it is absorbed by CO2 as fingerprint radiation.”
If this is correct then there was no way for the investigators at the south pole to discriminate between remission of LWIR from H2O and CO2. Both would be seen as identical blackbody radiation. Therefore there is no way to assign a 2:1 ratio to the two respective compounds.
Is the reemission mechanism described above not correct?
“doesn’t exist in a vacuum” is an expression meaning that something is not independent of its surroundings
i.e. Your child doesn’t exist in a vacuum, he lives in your family.
CO2 doesn’t exist in a vacuum, it resides in a mix of other gases which itself resides in a land/ocean/atmosphere system.
No. The concentration of CO2 absent the normal sinks of ocean and plant life over millions of years of continual emission from volcanism can rise to where it’s an appreciable percentage of the atmosphere comparable to water vapor today (up to 40,000 ppm) instead of the miniscule fraction (380ppm) it is today. A CO2 concentration that high would make its effect as a GHG 100 times more pronounced. There is virtually no possibility of CO2 reaching that level of concentration in any timeframe applicable to the CAGW brouhaha.
@899
There is considerable evidence of the earth being completely covered by icecap in the past. The ocean basins then effectively become like a corked bottle. In the meantime underwater volcanoes at plate boundaries (the “ring of fire” that runs around the earth like the seams on a baseball) continually adds CO2 to the corked bottle. The first thing to come along, say a meteor, which breaks the cork would release the dissolved CO2 somewhat like uncorking a bottle of champagne.
The mechanism that melts a snowball earth is not known with any degree of confidence but clearly something comes along to end the runaway freeze. That’s as good a scenerio as anything else.
anna v says:
July 26, 2010 at 10:29 pm
“and lets not enter into the quantum mechanical argument of entanglement”
Spoilsport.
I’d hardly call it an argument, though. It’s experimentally confirmed and approaching the point of practical application in quantum computers.
Granted I can’t see any relevance in atmospheric back radiation but I was sorely tempted to just throw it out there to dispute the notion that spooky action at a distance is a magical belief.
Dave Springer said:
“The investigators were surprised by the constancy of the H2O/CO2 ratio (2:1) in downwelling LWIR across seasons when measured absolute humidity varied widely yet didn’t cause any variation in the flux ratio.”
Hello Dave,
Does the above observation have any significance as regards Miskolczi’s findings ?
anna v says:
July 26, 2010 at 10:32 pm
Back radiation hand waving does not use the sun in the problem.
You haven’t understood the problem. Back radiation is about the reduced effectiveness of the earth to radiate the cnstant source of energy it gets from the sun. A bit like how the water in my kettle boils after a certain length of time because the constant source of energy is much greater than any heat losses.
This is the process known as thermalization, if it didn’t occur then the extra energy would just radiate away and the air would not heat up, this is not what’s observed. What Vonk is misled by is that N2 and O2 also transfer heat to CO2 molecules by collisions, however this still means that the lifetime of an individual vibrationally excited CO2 molecule (whether excited collisionally or radiatively) is orders of magnitude shorter than the mean time required to emit a photon.
.
Sorry Phil but you keep showing that you really have not a clue .
Considering the amount of nonsense in the statement quoted , your other statements are probably all similarily nonsensical .
It is not only 1 law of physics you violate but 4 what is rather much even for a layman .
.
Here they are :
1) You violate the time symmetry of the collision processes .
Indeed the equations of the collision processes are time symmetrical what means that if a CO2 molecules transfers energy to an N2 molecule then the N2 molecules will transfer energy to CO2 molecules . Statistically in LTE (Local Thermodynamic Equilibrium) the amount of energy transferred will be exactly the same in both directions by time symmetry .
2) By the same token you violate the energy conservation . As per Noether theorem , the time symmetry is equivalent to energy conservation . As you violated the time symmetry , you violated the energy conservation .
3) You also violated the energy equipartition law . This says that in LTE , the energy is partitionned equally between all degrees of freedom . As you “created” a privileged energy transfer from the vibrationnal degrees of freedom of CO2 to translational degrees of freedom of N2 you violated the energy equipartition .
4) Last but not least you violated the LTE conditions . By transferring energy in exclusively one direction (namely from vibrationnal degrees of freedom of CO2 to translationnal degrees of freedom of N2) the temperature of N2 diverges from the temperature of CO2 . The consequence is that the local temperature is no more defined what is not a good thing when one wants to talk about temperature .
5)Of course the statistical fact that the average time necessary to emit a photon is longer than the average time between collisions is irrelevant to the points 1-4 above . It certainly doesn’t mean like you seem to believe that CO2 emits no radiation . Quite on the contrary and especially for the resonant frequencies where CO2 is a good absorber !
It might be a shocking news for you but CO2 emits about as much 15µ radiation as it absorbs .
To help with your general education I would add that all this is textbook knowledge and can recommend you some good books initiating to QM .
.
And now ?
I expect that to get out of the hole you dug yourself in , you will pretend next that the low atmosphere is not in LTE and that Noether’s theorem is wrong …
Good luck 🙂
John Finn says:
July 27, 2010 at 3:31 am (Edit)
You haven’t understood the problem. Back radiation is about the reduced effectiveness of the earth to radiate the cnstant source of energy it gets from the sun.
The Earth’s surface (the bit that matters in terms of bulk energy transfer) doesn’t get a constant amount of energy from the sun. It is varying all the time due to albedo changes by much larger numbers of watts than co2 is involved with.
You are the one who hasn’t understood the problem.
Soooooooooooooo…..
(Sarc On)
We’re all agreed, then, the statement “The Science of AGW is settled!” is True!
(Sarc Off)
John Finn says:
July 27, 2010 at 3:31 am
You are out of your depth in this, do not swim any further.
http://en.wikipedia.org/wiki/Greenhouse_effect
The greenhouse effect is a process by which radiative energy leaving a planetary surface is absorbed by some atmospheric gases, called greenhouse gases. They transfer this energy to other components of the atmosphere, and it is re-radiated in all directions, including back down towards the surface. This transfers energy to the surface and lower atmosphere, so the temperature there is higher than it would be if direct heating by solar radiation were the only warming mechanism [
and this is Peden’s oven
As I read it I was thinking it might as I read it. The authors were particularly concerned about radiosonde humidity measurements not being accurate under conditions of extreme cold in the range of Antarctic interior continental surface temps in the winter.
Miskolczi’s hypothesis uses 61 years of radiosonde humidity measurements to support it and those measurements go well up into the stratosphere where presumably it is or can be as cold as Antarctic winter surface temps.
What I don’t know is whether Miskolczi needed high altitude humidity data. The amount of water vapor in the stratosphere is pretty slim to begin with and so doesn’t seem likely to be that’s where the action takes place. As well, Miskolczi only needed a decreasing trend in humidity to match the trend in increasing CO2 over the past 60 years. Barring significant changes in instrumentation the trend should be intact even if the readings are not accurate – they can be inaccurate so long as they’re consistently inaccurate if a trend is all you need. Even calibration procedural changes using the same hardware could cause a change but I believe those are well documented in metadata associated with the data set he was using.
Just as an aside, I was a meteorological equipment repair technician from 1974 to 1978 which included routine calibration of all the gear prior to launch – calibrating the radiosonde itself, the tracking antenna, and strip chart recorders. There were no procedural or hardware changes during my watch that I can recall.
I was rather hoping someone more expert in the history of experimental physics could point me to the experiment which surely must have been performed.
So much for that idea. Thanks for nothing.
I have read through all posts again.
I will illustrate the situation as it looks to me by introducing another experiment, using persons instead of spheres.(and some humour and exageration)
Person a) (Government person) says;
===========================
Look, the atmosphere is almost like a nuclear reactor. Photons acts almost like neutrons. Bouncing back and forth, never getting out! The temperature is increasing and we will soon reach critical mass!!!We’re all gonna die! (Yes, I know, its a bit over the top, but, close enough)
Person b) (Ordinary scientist working in private sector) says;
===========================================
But, but, isnt the athmosphere consisting of approx. 5% water vapour and only 0.04% CO2? Isnt there convection and evapouration going on all the time? There are clouds? Oceans? Surely if we increase with H2O instead of CO2 there would be no difference?
Surely, mr. government person, you cannot deny the existense of the natural cycles?
The temperature isnt increasing? Only GISS curves are, and we all know thats your curves, mr. govt. person?
Then the crux of the experiment;
Person c) passes by and says;
========================
Look, the optical Depth hasnt changed for 61 years.
What would be the normal chain of events after “Person c)” passes on this info?
How do we expect “person a)” to react?
Why does “person a)” react with indifference?
Because “person a)” works for the government. And 8 presidents did say the US govt must stop being dependant of foreign oil. Therefore CO2 must be declared a pollutant.
I find no other explanation.