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.
willis
The accusation of ignoring evidence was a device to goad you into responding. It worked and I’m not apologizing for it.
The main problem with your post is that you begin it with the impossible situation of the earth being a perfect black body with no atmosphere and say it would be “only” 8C cooler.
Yeah, but so what? The earth isn’t a perfect black body. Albedo plays a huge role in surface temperature. The heat flow experiments in Apollo 15 and 17 are excellent points of reference for what temperature realistic chunks of airless rock with non-zero albedos will attain at approximately 93 million miles from the sun.
Now you’re reduced to nit-picking by saying that two experiments deployed at mid-latitudes in full sun on the lunar surface aren’t enough to warrant consideration.
Well, here’s the deal with that. That’s still a heck of lot more warrant than your completely imaginary situation of a perfect black body. So there.
willis
To address your question of what’s up with the average between max daytime and nighttime surface temperatures being markedly different than subsurface average…
Someone else posted that and I’m not at all familiar with the reference it came from. The Apollo 15 and 17 heat flux experiments showed no such thing.
In fact there was no attempt to measure surface temperature in the heat flow rigs. It was only inadvertantly measured in the A15 setup because the astronaut couldn’t drill deep enough to bury all the thermocouples in one of the boreholes. As a result there were thermocouples (encased in a fiberglass rod) riding up a meter above the surface. Those above ground thermocouples yielded interesting information but it wasn’t regolith temperature, it was fiberglass temperature. In fact the most interesting thing they measured was a very small but gradual increase in nighttime minimum temperature. Several researches have speculated that the observed increase is due to increasing intensity of earthshine over the 5 years of data acquisition (1972 to 1977).
One might be interested in that as I believe back here on terra firma we had global cooling going on between 1972 and 1977. Increased earth albedo would give us global cooling and at the same time increase the intensity of earthshine on those inadvertantly exposed Apollo 15 ALSEP thermocouples.
Albedo in my opinion is what is really playing the big role in so-called climate change and a lot of the albedo change is in fact man-made by the deposition of black carbon (soot). Black carbon fits all the observations:
– it generates more heating at the surface than at altitude
– it has a limited range of effect of up to a few thousand kilometers from the source
– the sources are almost all in the northern hemisphere
– its effect is amplified by permanent snow cover as even during partial melts it floats to the surface getting darker and darker with each passing year
– recent experiments measuring earthshine on the moon show it decreasing
Even more interesting is the political ramifications of black carbon. The United States cleaned up its act with regard to black carbon decades ago. The primary offenders are Europe with their love of dirty deisel engines and poor countries that utilize slash/burn agriculture, heat their homes and cook their food by burning anything combustable in individual stoves and furnaces, and things of that nature. The United States then can’t be used for a scapegoat for global warming and in fact we would be the heroes instead of the villians. But NOooooooooooo. CO2 has to be the bogeyman so that the big wealthy United States gets the blame for it.
Is The Surface Unbalanced?
In my previous offering (Colin Davidson 18:18:13, 19MAR10) I used the Surface Balance equation to derive the sensitivity of the surface to “Surface Forcing”, and also calculated what that “Surface Forcing” must be to maintain a surface temperature which is 3DegC warmer.
The numbers turn out to be: a sensitivity between 0.095 and 0.15 DegC/W/m2, and an increase in “Surface Forcing” of between 22 and 32W/m2.
Joel Shore (19:04:26, 19MAR10) said:
“At the end of the day, the original forcing of ~4 W/m^2 from doubling CO2 results in another ~7 W/m^2 of “forcing” (in the sense of change in downwelling radiation at the TOA).The IPCC is not saying that ~4 W/m^2 increase in downwelling radiation at the TOA leads to a 3 C temperature rise…They are saying that ~4 W/m^2 of forcing results in feedback that increase the downwelling radiation by considerably more than that.”
As I understand this statement, the additional TOA “Radiative Forcing” at equilibrium for a 3DegC warmer planet is in the region of 12W/m2.
But this is nowhere near enough to keep the surface at an additional 3DegC warmer. Even if there is no additional evaporation, there needs to be 16W/m2 of additional downwelling radiation at the surface to cover the increased Stephan Boltzmann IR radiation.
And it is unrealistic to assume no increase in evaporation if the surface temperature increases. After all, my limited understanding is that the feedbacks invoked by the IPCC rely on increased water vapour.
So the additional amount of downwelling radiation, 12W/m2 is completely inadequate to maintain a 3DegC increase in surface temperature. It is between half and a third of what is required.
If you don’t get 22-32W/m2 you don’t get 3DegC. If you only have 12W/m2 you get between 1 to 1.5DegC.
Are all the models perpetually unbalanced at the surface? This seems quite likely based on the numbers cited by Joel.
anna v
“relevant to what?”
Relevant to the average surface temperature of an airless rock with an albedo around 10% orbiting around 93 million miles from the sun.
Why would you think that NOT relevant to a discussion of what the temperature of the earth’s surface would be absent an atmosphere?
I can’t help you out if you don’t understand why a thermocouple buried just deep enough in the moon so that there are no variations in it from day to day or year to year is not indicating the average surface temperature.
Brian G. Valentine says:
Well, I understand that in your state, you might feel that way. But, there are accepted ways that have worked well for our societies to distinguish between science and nonsense…and those scientific authorities have clearly come down on one side of the argument. And, in fact, you are so far out in the weeds on issues like G&T that even many who share your general view about AGW can’t stomach such nonsense.
Bryan says:
Ah…240 W/m^2 is an awfully lot of energy to store away by the methods that you are proposing. Besides which, the various energy flows can be measured, maybe not down to the fractions of a W/m^2 that one might ideally like, but certainly well enough to dismiss any notions that the earth’s temperature can grossly violate the constraints of radiative balance at will.
anna v
I worked my way through the video presentation on stefan boltzmann for undergraduates of Dr. David Archer over at realclimate. In those lectures he throws in this discussion about how much time it takes for energy (I’m not sure if you’d call it heat or radiation) to work its way through the atmosphere. I gathered those considerations were something apart and supplementary to just a discussion of stefan boltzmann proper. Is this as much as saying the earth’s atmosphere has an R value? I wonder what that value would be like – on an averaged out basis?
Colin Davidson: There is a reason why climate scientists like to talk in terms of the top-of-the-atmosphere and that is because the temperature at the surface is really governed by the top-of-the-atmosphere radiative balance and the processes that set the thermal structure of the atmosphere with height.
For example, in the book “Global Warming: The Hard Science” by L.D. Danny Harvey, he does a calculations where he shows that if you increase the downward infrared flux from the atmosphere at the earth’s surface by 10 W/m^2, you would only warm the surface by ~0.1 C (while cooling the atmosphere by 0.3 C). However, an externally-imposed 10 W/m^2 change in the greenhouse gas forcing produces (in his estimate, using an ~2 C per CO2 doubling climate sensitivity) about a 5 C surface temperature increase, i.e., a 50X larger response. The reason has to do with the atmospheric response: In the former case, the response is governed by turbulent heat exchange, which is very efficient in neutralizing the effect. However, in the latter case, the response is governed by the radiative damping to space, which is much weaker.
A thought experiment:
Joel, there was a day that you knew nothing about AGW. You never heard of it, but you had rational thought.
At that time, I held up a picture of the Earth and atmosphere in outer space. I pointed out temperatures to you at tropopause, Earth, and outer space. Then I asked, “which way is heat at the tropopause going?”
When you gave me the answer, “to space,” I corrected you, saying, “the downwelling radiation is an exchange with the warmer Earth, and increases the average surface temperature due to forcing at the tropopause”
… you would have taken me for a fool, trying to beguile you with misinformation
But then, Joel, people who you admired and evidently sympathized with, have sold you on an argument that you (I feel sure) would have taken for complete and utter nonsense.
Right out in the weeds, Joel
Re: Dave Springer (Mar 20 14:21),
I do not know about thermocouples, what about a diode?
Lets try again:
Temperature is what enters the radiation flow equations.
The temperature of the skin.
Temperature is not conserved. Energy is conserved. The -23- degrees 50cm in the ground have a deformed and unknown connection with whatever the average of the skin is: conduction equations and constants.
Take the average numbers in
http://www.asi.org/adb/m/03/05/average-temperatures.html
107C daytime
-153 night average
add and divide by two, as is done in the GISS records of earth temperature, and you find: -28C.
The actual average will be different, integrated correctly, but not the -23C 50cm in the ground.
Joel wrote (17:12:14, 20MAR10):
“Colin Davidson: There is a reason why climate scientists like to talk in terms of the top-of-the-atmosphere and that is because the temperature at the surface is really governed by the top-of-the-atmosphere radiative balance and the processes that set the thermal structure of the atmosphere with height. ”
Don’t the energy fluxes at both boundaries have to be in balance? There is no mechanism for the TOA to warm the Surface. It has no thermal mass to speak of, and is at a very feeble temperature. Declaring that the Surface is warmed by “the processes that set the thermal structure of the atmosphere with height” is akin to saying that the surface temperature is created by magic.
The Atmosphere is mostly warmed from the surface upwards. It is not warmed from the TOA downwards. At the surface (in a Kiehl & Trenberth Diagram, and at equilibrium – both these things are simplifications so that the Physics does not get bogged down in all the other variables) only two forcings are available – absorption of solar radiation, and back-radiation from the atmosphere. If you increase the temperature of the surface, how does one balance the new KT diagram at the elevated temperature?
Only by increasing the sum of the two forcings by a massive 22 to 32 W/m^2 can the surface remain balanced. If it is not balanced then it will cool down or heat up until it is balanced, regardless of what the TOA is doing. Allowing for the (very disputed) IPCC positive feedbacks, Joel has indicated that the additional downwelling radiation is 12W/m^2 or so. That’s not enough to maintain the surface at an additional 3DegC. The most you get is 1.5DegC.
There may be something I have missed here (most likely) but I don’t think Joel has identified what it is. At present I am forced to conclude that anyone who predicts more than 1.5DegC for a doubling of CO2 has a surface imbalance hidden in his model.
Joel Shore (17:12:14) :
“if you increase the downward infrared flux from the atmosphere at the earth’s surface by 10 W/m^2, you would only warm the surface by ~0.1 C”
This sounds very strange. Has he developed a service pack for the S-B law?
Colin Davidson (00:21:13) :
How do you arrive at “a massive 22 to 32 W/m^2” ?
Brian G Valentine says:
Yes, and if by heat you mean net heat (which is really the only logical thing you could talk about as flowing only in one direction) then I would to this day say that you are wrong. The net heat flow is in fact to space. It is in Willis’s steel greenhouse, it is in the Trenberth & Kiehl diagram, and it is in any other explanation of the greenhouse effect that I have seen.
It is just that the heat flow into space is less than it would be if the atmosphere were transparent to IR radiation (and the Earth’s surface were still at its current temperature).
anna v
You don’t know what a thermocouple is? That is taught in high school physics. Very basic stuff. What grade are you in?
Igl says:
No…It is just that the earth’s surface can exchange heat with the atmosphere by other processes besides radiation. However, the earth system as a whole can only exchange radiation with space by radiation.
Joel
I take it you agree with me that there is no law of conservation of radiation!
……..but certainly well enough to dismiss any notions that the earth’s temperature can grossly violate the constraints of radiative balance at will….
But then you try to bend it back to some kind of law that does not hold unless you try to grossly violate it!
My boat uses a solar panel to keep my batteries charged up until I need to convert the chemical potential energy into some other form of energy of my choosing.
The coal that I use in my fire releases energy that was stored over 400 million years.
You could yourself think of countless other examples of EM radiation being converted into other energy forms.
The preoccupation by “consensus”advocates on radiation balance is leading them into serious errors.
Also on the topic of the millions of scientists beavering away fully united in support of a co2 greenhouse effect is as bogus as the effect itself.
What any sceptic finds is this theory is like an inverted triangle balanced on a tiny base.
The three sets of so called independent data supporting the theory is reduced to two because of the Phil Jones affair.
We then find that the other two were not as independent as claimed.
The sceptics choose a variety of methods to test the AGW theory.
Some do it by actually checking the data to see it it supports the theory.
Some do it by providing an alternative theory such as solar flares.
Some(mainly geologists) take a historical approach to find out if the present time is highly unusual.
Others like G&T check to see if the Physics behind AGW theory stacks up.
To expect all sceptics to be in total agreement with one another is really stupid.
I am from a Physics background and I must say I am much more impressed by G&T than any counter argument.
In fact some of those attacking G&T show serious signs of scientific ignorance.
If say a Physics Professor specialising in Heat Transfer Thermodynamics was to criticise their paper, I’m sure they would regard that as a serious challenge, but as yet this has not happened.
Dave Springer, I don’t exactly care for that kind of tone directed at Anna because you’ve got no basis for it
anna v
You made a mistake in your calculation:
diurnal mean temperature swing = 107+153 = 260
half of diurnal change = 260 / 2 = 130
half of diurnal change added to nightime mean = -153 + 130 = -23
half of diurnal change subtracted from daytime mean = 107 – 130 = -23
Actual measured regolith temperature at 50cm depth was, unsurprisingly, a constant -23C.
QED
Bryan says:
Look, you could also complain that climate scientists don’t include the effects of quantum gravity or the relativistic corrections to the speeds of winds and ocean currents. The question is whether this is at all relevant. I haven’t done the calculation myself but I’ll give you a hint from what I do know: All those fossil fuels that accumulated over hundreds of millions of years that we are now burning very rapidly (relative to the time that it took them to form) amounts to an energy usage averaged over the earth’s surface of ~0.02 W/m^2.
And, by the way, your solar panel only successfully converts a small fraction of that energy and what it stores gets converted eventually into heat when you run your boat. In the end, the net amount of energy you store in that battery averaged over the course of year will be very small (and will be either negative or positive depending on whether the battery is in a more or less charged state at the beginning of the year as at the end).
We are also measuring the various energy fluxes and, while we can’t yet measure them to the fraction of a W/m^2 that would be necessary to directly measure what radiative balance there is, I believe that they are measured accurately enough to say empirically that there is radiative balance within at least a few W/m^2.
There are so many things I could say to this that I don’t know where to start:
(1) One doesn’t need to be a specialist in heat transfer thermodynamics to understand that G&T is nonsense.
(2) Most “skeptics” like to say that it is not the credentials that matter but rather the argument. So, why should G&T only take seriously those with such credentials?
(3) G&T are hardly the ones in the position to be deciding what constitutes a serious challenge to their paper. The fact that it was published at all is an extreme embarrassment and nobody in the field is taking it seriously. In fact, one of my motivations for participating in the comment debunking it was the notion that it was a public service so that the climate scientists themselves could focus on real science rather than wasting their time dealing with such nonsense. (I also felt a sense of duty as a physicist since the paper appeared in a physics journal and G&T make much of the fact that their physics viewpoint somehow allows them to see what others have missed.)
(4) As it happens, I am a physicist who has published papers in the area of statistical physics (which really provides the underlying foundations for thermodynamics) in some of the top physics journals in the world (e.g., Physical Review Letters). I have also done some heat transfer calculations in a more practically-oriented corporate research and development environment.
Re: Dave Springer (Mar 21 07:42),
Well, I did make an arithmetic mistake
(-153+107)/2 makes -23.
(I was hurrying to keep an appointment, if that is an excuse for bad arithmetic)
I consider it serendipitous, or maybe the choice of 50cms was made because of the coincidence of the numbers ?
Temperatures on the Lunar surface vary widely on location. Although beyond the first few centimeters of the regolith the temperature is a nearly constant -35 C (at a depth of 1 meter), the surface is influenced widely by the day-night cycle.
so -23 is a choice, why not -35 as this reference says?
http://www.asi.org/adb/m/03/05/average-temperatures.html
BTW, I am a retired particle physicist doctorate and all.
Joel Shore (06:50:50) :
But only 20% of the energy transport from the surface is non-radiative. Why would suddenly most of the added 10 W be returned as non-radiative? Still sounds very strange.
… and 5 C after a CO2 doubling?? That’s 27.8 W/m2 more from the surface + the non-radiation, or a 7.5 amplification of the 3.7 W. I really don’t understand any of this …
Joel
I can hardly believe some of the things you are writing.
You claim to be a Physicist yet you think there is such a thing as conservation of radiation.
Point me in the direction of one Physics book to back up your claim
….We are also measuring the various energy fluxes and, while we can’t yet measure them to the fraction of a W/m^2 that would be necessary to directly measure what radiative balance there is, I believe that they are measured accurately enough to say empirically that there is radiative balance within at least a few W/m^2………..
The total energy stored in fossil fuels over millions of years can be ignored apparently
… I haven’t done the calculation myself but I’ll give you a hint from what I do know: All those fossil fuels that accumulated over hundreds of millions of years that we are now burning very rapidly (relative to the time that it took them to form) amounts to an energy usage averaged over the earth’s surface of ~0.02 W/m^2…….
Please send this information to the IPCC
I have pointed you to elementary mistakes by A. P. Smith and you just brush them aside
You are completely contemptuous of G&T yet all you produce is a string of insults with no serious attempt to deal with any of the many points they make.
You claim to have produced more papers than Rupert Murdoch, so we will just have to take that on trust.
When and if your refutation is published we can then check just what the qualities of the papers were.
On present evidence of yourself, A.P.Smith, Eli Rabett and so on I think that G&T will not be losing any sleep.
I hope your paper will be read and given constructive criticism.
The usual way to resolve matters of scientific fact is to point to some experimental proof rather than a computerised projection.
The ability to hurl insults is inversely proportional to scientific proof.
Igl: No…In that calculation, Harvey assumed a 5 C increase from an imagined 10 W/m^2 forcing. Since a CO2 doubling is ~4 W/m^2 forcing, he is assuming a sensitivity of ~2 C per doubling.
Thank you, Joel.
So then at the tropopause, to make the surface temperature higher, the radiant heat of the Earth is
– reflected back to Earth at the tropopause (nope)
– absorbed by some molecules there and re-radiated …
… Which way. You tell me which way the radiation is going – up, or down.
The answer is: The radiation at the tropopause is going the opposite direction that AGW theory is going
Willis –
I have to say I have read through this entire thread (I’m home sick with a bad cold), and I am impressed at how calm and professional you remain in the face of many reasons not to.
Great job.
In the interest of transparency, I will say that I have a PhDEE, I love Physics, have read several books on the subject of “Global Warming” including the CRUTAPE letters and very much appreciate this website. Hats off to all of you guys who work to stay objective.
Thanks,
Mike