Guest Post by Willis Eschenbach
OK, a quick pop quiz. The average temperature of the planet is about 14°C (57°F). If the earth had no atmosphere, and if it were a blackbody at the same distance from the sun, how much cooler would it be than at present?
a) 33°C (59°F) cooler
b) 20°C (36°F) cooler
c) 8° C (15°F) cooler
The answer may come as a surprise. If the earth were a blackbody at its present distance from the sun, it would be only 8°C cooler than it is now. That is to say, the net gain from our entire complete system, including clouds, surface albedo, aerosols, evaporation losses, and all the rest, is only 8°C above blackbody no-atmosphere conditions.
Why is the temperature rise so small? Here’s a diagram of what is happening.
Figure 1. Global energy budget, adapted and expanded from Kiehl/Trenberth . Values are in Watts per square metre (W/m2). Note the top of atmosphere (TOA) emission of 147 W/m2. Tropopause is the altitude where temperature stops decreasing with altitude.
As you can see, the temperature doesn’t rise much because there are a variety of losses in the complete system. Some of the incoming solar radiation is absorbed by the atmosphere. Some is radiated into space through the “atmospheric window”. Some is lost through latent heat (evaporation/transpiration), and some is lost as sensible heat (conduction/convection). Finally, some of this loss is due to the surface albedo.
The surface reflects about 29 W/m2 back into space. This means that the surface albedo is about 0.15 (15% of the solar radiation hitting the ground is reflected by the surface back to space). So let’s take that into account. If the earth had no atmosphere and had an average albedo like the present earth of 0.15, it would be about 20°C cooler than it is at present.
This means that the warming due to the complete atmospheric system (greenhouse gases, clouds, aerosols, latent and sensible heat losses, and all the rest) is about 20°C over no-atmosphere earth albedo conditions.
Why is this important? Because it allows us to determine the overall net climate sensitivity of the entire system. Climate sensitivity is defined by the UN IPCC as “the climate system response to sustained radiative forcing.” It is measured as the change in temperature from a given change in TOA atmospheric forcing.
As is shown in the diagram above, the TOA radiation is about 150W/m2. This 150 W/m2 TOA radiation is responsible for the 20°C warming. So the net climate sensitivity is 20°C/150W-m2, or a temperature rise 0.13°C per W/m2. If we assume the UN IPCC canonical value of 3.7 W/m2 for a doubling of CO2, this would mean that a doubling of CO2 would lead to a temperature rise of about half a degree.
The UN IPCC Fourth Assessment Report gives a much higher value for climate sensitivity. They say it is from 2°C to 4.5°C for a CO2 doubling, or from four to nine times higher than what we see in the real climate system. Why is their number so much higher? Inter alia, the reasons are:
1. The climate models assume that there is a large positive feedback as the earth warms. This feedback has never been demonstrated, only assumed.
2. The climate models underestimate the increase in evaporation with temperature.
3. The climate models do not include the effect of thunderstorms, which act to cool the earth in a host of ways .
4. The climate models overestimate the effect of CO2. This is because they are tuned to a historical temperature record which contains a large UHI (urban heat island) component. Since the historical temperature rise is overestimated, the effect of CO2 is overestimated as well.
5. The sensitivity of the climate models depend on the assumed value of the aerosol forcing. This is not measured, but assumed. As in point 4 above, the assumed size depends on the historical record, which is contaminated by UHI. See Kiehl for a full discussion.
6. Wind increases with differential temperature. Increasing wind increases evaporation, ocean albedo, conductive/convective loss, ocean surface area, total evaporative area, and airborne dust and aerosols, all of which cool the system. But thunderstorm winds are not included in any of the models, and many models ignore one or more of the effects of wind.
Note that the climate sensitivity figure of half a degree per W/m2 is an average. It is not the equilibrium sensitivity. The equilibrium sensitivity has to be lower, since losses increase faster than TOA radiation. This is because both parasitic losses and albedo are temperature dependent, and rise faster than the increase in temperature:
a) Evaporation increases roughly exponentially with temperature, and linearly with wind speed.
b) Tropical cumulus clouds increase rapidly with increasing temperature, cutting down the incoming radiation.
c) Tropical thunderstorms also increase rapidly with increasing temperature, cooling the earth.
d) Sensible heat losses increase with the surface temperature.
e) Radiation losses increases proportional to the fourth power of temperature. This means that each additional degree of warming requires more and more input energy to achieve. To warm the earth from 13°C to 14°C requires 20% more energy than to warm it from minus 6°C (the current temperature less 20°C) to minus 5°C.
This means that as the temperature rises, each additional W/m2 added to the system will result in a smaller and smaller temperature increase. As a result, the equilibrium value of the climate sensitivity (as defined by the IPCC) is certain to be smaller, and likely to be much smaller, than the half a degree per CO2 doubling as calculated above.
I understand where this is coming from, Bill, but where I (and apparently Gerlich and Tscheuscher and a lot of others) have the worst difficulty, is accepting the idea that the “atmosphere” is “warming” the “surface”.
Either that idea violates the Second Law or it doesn’t. If someone could just present ONE parallel example to show this is at least possible, then I would not say that Gerlich and Tscheusher’s analysis is as good as anyother application of the Second Law
Very interesting post Mr. Eschenbach; it is great to see the varied, open air give and take between you and and the variety of posters who question several of your points.
I enjoyed reading, if not fully understanding, nearly all the posts and your responses to them.
Infinitely more interesting than anything on the boob tube. Thanks.
Brian W (01:59:09) :
Steve Goddard (23:47:55)
The shell of your airplane heated due to air friction! Blankets indeed!
Blankets. The air friction at 35000 ft is the same as 5000 ft is the airplane is flying at the same indicated airspeed, and airliners do stay in a fairly small range of indicated airspeeds. The thinner air up high requires they fly a much faster true airspeed for the wings to generate the lift, but the dynamic pressure the airplane feels is about the same.
Re: Brian G Valentine (Mar 18 22:12),
I understand where this is coming from, Bill, but where I (and apparently Gerlich and Tscheuscher and a lot of others) have the worst difficulty, is accepting the idea that the “atmosphere” is “warming” the “surface”.
Yes.
http://discover.itsc.uah.edu/amsutemps/execute.csh?amsutemps+001
At 36000 feet (15km) temperatures play between -47.5 to -46.5.
at 14000 feet (5km) -21.5 to -19.5
near surface 20.8 to 21.5
Now basic thermodynamics says heat is not transferred from a cold body to a hot body without work being done. That is elementary . CO2 is not doing any work ( running a compressor circuit, at least it has not been shown as such).
The earth is a macroscopic body. There is absolutely no reason not to calculate everything within classical thermodynamics : there are no coherent phenomena and radiation is included in classical thermodynamics. If one wants to calculate the effect of a change in the composition of the gas, one has to calculate the effect of the change in the heat capacity of the medium, to see what happens in the heat transports.
The confusion with the quantum mechanical guts of the molecules of the atmosphere is what , in my opinion, makes for double counting.
One can work with quantum statistical mechanics, but then one should use that formulation throughout, making statistical ensembles and studying their evolution etc. Mixing two techniques over the same material creates the contradiction.
Perhaps one method of calculating climate sensitivity to some parameter, like increasing CO2 concentration, would be to calculate how much a very small step change in the controlling parameter would change the effective Stefan-Boltzmann temperature of the total energy that escapes from the top of the atmosphere. I suspect the negative of this change might give the surface temperature change required to make up the difference.
Of course this would all assume that we knew how to make such calculations in the first place.
Lief
Tsk Tsk
Tsk Tsk has my vote on this one. Lief, you define the two spheres as having a temperature of 400 but you also imply that the spheres as have equal power generation. If these two are defined then they must have identical heat losses equal to the power generated, for the temperature to remain constant. But you also define them as having different emmissivities (one is black and one is white). You cannot define all these three as being true. As Tsk Tsk says the system is overdefined. Tsk Tsk also clarified the point that good absorbers are good emmitters and vice versa so that energy laws are not violated.
Leif Svalgaard (18:03:44)
I don’t know if that’s humor or not … I hope it is.
Perhaps you could explain what he means by:
Also, I looked at the site he discusses, the University of Michigan Boring Hole Site or whatever it’s called. Here’s what they say:
Now, the error given for the HadCRUT3 dataset, which uses actual temperatures, is about two tenths of a degree in 1850 … and these guys want me to believe that they can look in boreholes that have wildly varying temperature profiles and give us the temperature 500 years ago with an error of a tenth of a degree???
You’re welcome to believe that, Leif, perhaps you’re like the Red Queen who believes six impossible things before breakfast. I’m not that skilled, I’ll pass.
It appears that you believe the canard that skeptics don’t think the earth is warming. Most skeptics I know and respect believe it is warming. So why would we reject something that shows the earth is warming? I reject it for other reasons.
Juckes and the Mitrie project are unethical imitations of scientists. Inter alia, they put up a paper and invited public comment, saying that they would consider the comments before publishing it. I and a number of others put a lot of time into it, uncovered serious scientific flaws in the claims, and then they just blew us off and published anyhow. Plenty of information here on their scientific malfeasance.
So I’ll pass on that one too. It’s just another puff piece from UMich, repeating their claim of a tenth of a degree accuracy a half a millennium ago. That claim doesn’t pass the smell test, and I’m astounded that you would recommend a paper claiming that accuracy.
Finally, I note that your borehole reconstruction shows the Medieval Warm Period, and theirs shows nothing of the sort … which one is wrong? Yours is about a degree different from theirs back 500 years, and they claim an error of 0.1°C … I’m sure you can see the problem.
Joel Shore (19:30:38)
If I am following your argument, you misunderstand the “per CO2 doubling”. This is just how the IPCC tends to measure climate sensitivity. It has nothing to do with how much of any given forcing is from CO2. It is merely a unit of measurement.
For example, we could say that climate sensitivity is 1°C/W-m2, or we could say that climate sensitivity is 3.7°C / CO2 doubling. There is absolutely no difference between those statements. They are just expressed in different units. The conversion factor is
1 CO2 doubling = 3.7 W/m2
or
1 W/m2 = 0.27 CO2 doublings
So we can convert from one unit to the other, and it means nothing about whether we are talking about cloud forcing or H2O forcing or CO2 forcing. It’s just different units.
Brian G Valentine (22:12:19)
Once again, see my post, “The Steel Greenhouse”. It shows that the greenhouse effect has nothing to do with gas, or lapse rate, or any of that. If you have problems with the concepts there, let me know.
w.
Joel Shore (17:27:26) :
daniel says:
As to Joel Shore announcement of a peer reviewed “comment on G&T” paper, will this be more successful that Smith tentative ? anyway is the paper already available through Arxiv ?……
Looking forward to reading your paper but I have to agree with Daniel that the previous so called refutations of G&T have backfired.
I would invite anyone who has any doubts on the matter to go to Arthur P Smith website and the thread “the arrogance of Physicists”.
Arthur has great difficulty coping with Fred Staples and Terry Oldberg never mind G&T
Willis Eschenbach (01:56:43) :
“That’s where careful cherry picking comes in.”
I don’t know if that’s humor or not … I hope it is.
It was not. You can [and did] pick two close boreholes that give different results. That is the cherry. For it not to be cherry picking you will have to show that any two close boreholes are always wildly different, which they are not.
Finally, I note that your borehole reconstruction shows the Medieval Warm Period, and theirs shows nothing of the sort … which one is wrong?
One only went back to 1500, so cannot show the MWP.
The error bar is probably calculated from the spread of the 837 individual reconstructions. Let that be, typically [go look at several] 3 degrees, then the usual 1-sigma error of the mean would be 3/sqrt(836) = 0.10 degrees. You can find the individual reconstructions here http://www.ncdc.noaa.gov/paleo/borehole/core.html
I do believe [Red Queen-like] the borehole technique is sound. This does not guarantee that all applications of it are.
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HankHenry (19:12:32) :
Willis tells us “The average temperature of the planet is about 14°C.” Of course that’s disregarding the massive cold of the ocean which is more like 4°C – averaged out. What is it that makes the oceans so cold? Two miles down on the continents the earth is quite warm, but two miles down in the oceans it’s quite cold. It suggests to me there is a refrigeration process of some sort extracting heat from the depths. Also, do I remember my grade school science correctly when I say the total mass of the atmosphere is represented by the mass of just 33 feet of water – the theoretical lifting limit of a suction pump?
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No, it’s rather simple physics — the earth’s crust (in this case, the sea bottom) is a very good insulator because of its thickness. And, surprisingly, the warmer water above the cold-water layer is also a good insulator because of its thickness and also the water’s general stratification (little mixing).
The cold water is there because cold meltwater from glaciers and exposure to arctic air causes it to sink, and is then preserved below by the insulation above and below it. The cold water would eventually warm up, but it’s being replaced by more cold water continuously, so a equilibrium situation arises such as we observe. The cold deep-water is a reminent of the previous ice-ages.
Heat conduction is a feeble way to transfer heat compared to convection and even radiation, especially when there is little mixing (stratified).
Brian Valentine
I don’t understand why you responded since you had nothing to offer in way of explanation why the constant subsurface temperature of lunar regolith in the middle latitudes agrees very closely with the oft-cited figure of the earth being heated approximately 30 degrees celsius through greenhouse gases.
There are many studies of the optical properties of lunar regolith available. It isn’t exotic material of any sort and that shouldn’t be surprising given the moon is made of the same material as the earth. Lunar regolith is generally darker than earth surfaces because “space weathering” of the soil darkens it. Fresh impact craters have bright rays coming out from them because it is newly exposed regolith which has yet to be darkened by space weathering.
I believe the data from the Apollo experiments thoroughly disproves Willis’ hypothesis of only 8 degrees celsius heating from GHG. His continued silence on it I’m taking as a tacit admission that he can’t account for it and rather than admit an error is choosing to simply ignore the inconvenient data. I had thought hiding contrary data that doesn’t agree with theoretical model predictions was a tactic used by the AGW alarmists. I’m very disappointed to see it being employed by the anti-alarmists.
Joel Shore (18:35:55) :
Well I should have emphasized that I find it “surprising” only if I force myself to look at things in a certain innocent way.
Regarding our release of carbon that had been locked away… just like you point out that our energy use is tiny compared with what we get from the Sun, I shall point out that our release of carbon is also tiny compared with the vast transactions between the different parts of the system. This NASA chart of the carbon cycle is illustrative for piece of mind, if viewed with proper calm:
http://nasascience.nasa.gov/earth-science/oceanography/ocean-earth-system/ocean-\carbon-cycle
From that chart, you see that total amount of carbon in the extant fossil fuels still in the ground is roughly 1/8 the amount of carbon in the active system. The amount we are recycling annually back into the system is about 0.015% of the total carbon in the system.
The cause for alarm, it seems to me, comes only if you adopt the assumption that our modest recycling program represents a very grave disturbance to a static and balanced system, whose balance coincides with its state around 1850. I consider this assumption to have no rational or scientific basis whatsoever. It is merely ideological.
To begin with, the carbon we are releasing was once part of that dynamic system. We are recycling it back into life at what appears like a reasonable rate.
A few years ago there was some talk of a “missing sink” to refer to the apparently surprising fact that about half the CO2 we release does not accumulate in the atmosphere. This nonsensical phrase has now been sensibly dropped. How can sinks be missing? The surprise came only from the unwarranted assumption that the other entities that hold CO2 should refuse to take any extra amounts, on some kind of unwritten principle of carbon austerity by plants and oceans.
But why on earth would it be surprising that the plants take notice of variations in what is available for them to take – and proceed take it – as they are indeed taking it. Didn’t they once hold much of the very carbon we are now putting back in circulation? And why would it be surprising that the oceans also “take notice” of variations in the partial pressure of this gas in the atmosphere, and open their huge arms accordingly?
Alternatively, for illustrative purposes, you could look at the atmosphere as a giant pool with huge drains and pipes leading in and out of two other giant pools represented by the oceans and the plants/soil. So now we add our own little dripping faucet contribution to this giant global commerce, and we take ourselves so seriously that we assume the huge drains of this pool will be overwhelmed by our contribution, which will thus accumulate indefinitely. There are ribald jokes about ants having grandiose perceptions of their sanitary relations with elephants, or ants standing on a railway track and worried sick that they may cause a catastrophic derailment of the next train. I find them appropriate, sometimes, to the AGW discussions.
I think it could probably be demonstrated that even a doubling of CO2 concentrations from current levels is extremely unlikely, if not impossible, as a strict consequence of our contribution.
Thank you Anna. Somebody tried to tell me that the “work” expended to accomplish this is the pV work done “by” the atmosphere; that certainly cannot be. One could in principle write down quantum statistical conservation and evolution conditions I suppose; don’t know how much meaning that would have on getting some numbers out of it unless some dramatic simplifications could be made (like if it was near zero Kelvin).
Thank you Willis for your most enlightening construct. I might have normalized to radiance quantities energy/unit area/unit if solid angle to possibly avoid some difficulty of interpretation of conserved quantities.
Wonderful weather here on the Mid Atlantic region this past week! I just can’t WAIT for some watermelons to start howling that it’s “too warm” and can’t we pass an energy and climate bill to fix this problem?
(You think I’m kidding? I’m not kidding one bit.)
Bryan (04:13:36) :
I would invite anyone who has any doubts on the matter to go to Arthur P Smith website and the thread “the arrogance of Physicists”.
And to compare with: http://arxiv.org/ftp/arxiv/papers/0904/0904.2767.pdf
Professor Kramm sent to me that response, I would hope this appears someplace else other than good old arXiv
Anyway I still believe Gerlich and Tscheuschner,
… they oughta take me outside, and shoot me …
Can anyone tell me why it is not hotter in the desert on a humid day (when there is a lot of the best GHG) than on a very dry day?
The greenhouse effect is due to the fact that the atmosphere has a finite temperature and therefore emits radiation towards the surface. The surface receives more radiation from the atmosphere than it does from the sun.
The amount of warming generated by the atmosphere is about 7C per kilometer or 70-80C. This is well established, and as Feynman said :
It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.
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Brian G Valentine (06:06:09) :
Thank you Anna. Somebody tried to tell me that the “work” expended to accomplish this is the pV work done “by” the atmosphere; that certainly cannot be.
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I had alittle trouble w/this issue until I thought alittle.
Work compressing a gas does cause it to rise in temp. But once the compression is finished, the gas will cool back to ambient. So a gas under static conditions (even at an extremely high pressure) w/no further work being done on it , doesn’t produce any heat & will return to ambient temp. Standard gas cylinders of compressed H2 are @ur momisugly 2000 psi, but they’re at ambient temp once the heat of filling it (work) transfers away.
The earth does in fact do “work” of compression on descending air masses (high-pressure systems) & Chinook-type winds, but since the atmosphere is of a fixed mass & volume, air will have to rise somewhere else & then “cooling” occurs, as in low-pressure systems. The temp effects balance out & for the whole earth are zero. The earth as a whole isn’t doing any net “work” on the atmosphere.
“The amount of warming generated by the atmosphere is about 7C per kilometer or 70-80C. This is well established, and as Feynman said :
It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.”
For Feynman’s sake where is the empirical evidence that “well-establishes” this?
beng: what you say is accurate. But don’t forget that a gas at, say 20 C, possesses a lot of potential and kinetic energy. This is stored energy, which manifests itself as heat and causes the thermometer to read 20 C. A column of air several miles high has to have a lot of stored heat in it to exist. In fact, the amount of such stored heat is probably equivalent to the “greenhouse effect.”
JAE,
http://mtp.jpl.nasa.gov/missions/cirex/results.html
http://en.wikipedia.org/wiki/Lapse_rate
JAE,
Nights in the desert are much warmer when it is humid, due to the increased GHG.
Leif Svalgaard (05:01:34)
Ah, I mistook your meaning.
Boreholes like this are fairly common.I found a number of them very quickly. Unfortunately, most boreholes are a ways from each other, so it’s hard to tell.
But if the boreholes are connected to temperature, temperature is well correlated at distances up to about 1,000 km, and falls off fairly linearly. I have never seen a borehole study that claimed that, and I doubt it greatly.
Oh, please. Yours shows that 500 years ago was a full degree warmer than theirs. You claim this is from the MWP, which in your reconstruction is about 600 years ago. Stop tap dancing and answer the question — why is your reconstruction a degree warmer than theirs 500 years ago if their error bar is only a tenth of a degree?
Yes, I know that’s how the error bar is constructed. I just don’t believe it is meaningful. Let me see if I can explain why.
Suppose we have a thermometer, and the actual temperature is 10.55°C. I ask people to read it to the nearest degree. I have ten thousand people read it. As you might expect, about half of them say the temperature is 10C, and the other half say it is 11C. We end up with an average of 10.5°, and an actual error of 0.05°C
OK. The standard error of a group of observations is the standard deviation divided by the square root of the number of observations N. In this situation, we end up with the numbers saying that the temperature is 10.5C with a standard error of ± 0.005°C … which is clearly wrong, because the real temperature is no less than ten, count them, ten standard errors away from the calculated value.
But wait, it gets worse. What if the errors are asymmetrical, that is to say biased to one side or the other? For example, if it is very very cold, people will tend to round their temperature off to the cold side. It’s only human.
Suppose that because of that tendency, instead of the readings coming back 50/50 above and below the real temperature, that the split is 60/40 to the cooler side. Not much of a change.
But in that case, the result is no less than 29 standard errors away from the true value.
So there are two problems. The first one is the inherent accuracy of the measurement technique. My rule of thumb is that no matter how many measurements we take, we can’t gain more than one decimal of accuracy over the original measurements. In other words, if we are measuring to the nearest degree, our error can never be less than a tenth of a degree, no matter how many measurements we take. And when two adjacent boreholes give widely varying answers as to the temperature 500 years ago, we are using a very crude measuring stick.
The second one is asymmetrical errors. For boreholes the main one of these is plain old water. I used to make my living drilling water wells, so I’m more than a bit familiar with this.
As a borehole goes down into the earth, we expect it to get warmer. This is because the core of the earth is really hot, and the heat slowly flows upwards.
Now, if there is water coming out of the side of the borehole anywhere, it will cool the borehole. And because gravity only goes one direction, it will cool the part of the borehole which is deeper, but not the shallower part.
This, of course, introduces an asymmetrical error into the data, with more boreholes expected to show spurious warming because the older (deeper) parts are cooler.
Now, these problems with error calculations have been known for centuries. For the borehole folks to ignore them and claim that they can measure the global temperature a half a millennium ago with a smaller error than we can do with 1850 temperature records tells me one thing …
We’re not dealing with borehole scientists. We’re dealing with borehole acolytes.