Guest Post by Willis Eschenbach.
For all of its faults, the IPCC (Intergovernmental Panel on Climate Change) lays out their idea of the climate paradigm pretty clearly. A fundamental part of this paradigm is that the long-term change in global average surface temperature is a linear function of the long-term change in what is called the “radiative forcing”. Today I found myself contemplating the concept of radiative forcing, usually referred to just as “forcing”.
So … what is radiative forcing when it’s at home? Well, that gets a bit complex … in the history chapter of the Fourth Assessment Report (AR4), the IPCC says of the origination of the concept (emphasis mine):
The concept of radiative forcing (RF) as the radiative imbalance (W m–2) in the climate system at the top of the atmosphere caused by the addition of a greenhouse gas (or other change) was established at the time and summarised in Chapter 2 of the WGI FAR [First Assessment Report].
Figure 1. A graph of temperature versus altitude, showing how the tropopause is higher in the tropics and lower at the poles. The tropopause marks the boundary between the troposphere (the lowest atmospheric layer) and the stratosphere. SOURCE
The concept of radiative forcing was clearly stated in the Third Assessment Report (TAR), which defined radiative forcing as follows:
The radiative forcing of the surface-troposphere system due to the perturbation in or the introduction of an agent (say, a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long-wave; in Wm-2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values.
In the context of climate change, the term forcing is restricted to changes in the radiation balance of the surface-troposphere system imposed by external factors, with no changes in stratospheric dynamics, without any surface and tropospheric feedbacks in operation (i.e., no secondary effects induced because of changes in tropospheric motions or its thermodynamic state), and with no dynamically-induced changes in the amount and distribution of atmospheric water (vapour, liquid, and solid forms).
So what’s not to like about that definition of forcing?
Well, the main thing that I don’t like about the definition is that it is not a definition of a measurable physical quantity.
We can measure the average surface temperature, or at least estimate it in a consistent fashion from a number of measurements. But we can never measure the change in the radiation balance at the troposphere AFTER the stratosphere has readjusted, but with the surface and tropospheric temperatures held fixed. You can’t hold any part of the climate fixed. It simply can not be done. This means that the IPCC vision of radiative forcing is a purely imaginary value, forever incapable of experimental confirmation or measurement.
The problem is that the surface and tropospheric temperatures respond to changes in radiation with a time scale on the order of seconds. The instant that the sun hits the surface, it starts affecting the surface temperature. Even hourly measurements of radiative imbalances reflect the changing temperatures of the surface and the troposphere during that hour. There is no way that we can have the “surface and tropospheric temperatures and state held fixed at the unperturbed values” as is required by the IPCC formulation.
There is a second difficulty with the IPCC definition of radiative forcing, a practical problem. This is that the forcing is defined by the IPCC as being measured at the tropopause. The tropopause is the boundary between the troposphere (the lowest atmospheric layer, where weather occurs), and the stratosphere above it. Unfortunately, the tropopause varies in height from the tropics to the poles, from day to night, and from summer to winter. The tropopause is a most vaguely located, vagrant, and ill-mannered creature that is neither stratosphere nor troposphere. One authority defines it as:
The boundary between the troposphere and the stratosphere, where an abrupt change in lapse rate usually occurs. It is defined as the lowest level at which the lapse rate decreases to 2 °C/km or less, provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 °C/km.
This is an interesting definition. It highlights that there can be two or more layers that look like the tropopause (little temperature change with altitude), and if there is more than one, this definition always chooses the one at the higher altitude.
In any case, the issue arises because under the IPCC definition the radiation balance is measured at the tropopause. But it is very difficult to measure the radiation, either upwelling or downwelling, at the tropopause. You can’t do it from the ground, and you can’t do it from a satellite. You have to do it from a balloon or an airplane, while taking continuous temperature measurements so you can identify the altitude of the tropopause at that particular place and time. As a result, we will never be able to measure it on a global basis.
So even if we were not already talking about an unmeasurable quantity (radiative change with stratosphere reacting and surface and tropospheric temperatures held fixed), because of practical difficulties we still wouldn’t be able to measure the radiation at the tropopause in any global, regional, or even local sense. All we have is scattered point measurements, far from enough to establish a global average.
This is very unfortunate. It means that “radiative forcing” as defined by the IPCC is not measurable for two separate reasons, one practical, the other that the definition involves an imaginary and physically impossible situation.
In my experience, this is unusual in theories of physical phenomena. I don’t know of other scientific fields that base fundamental concepts on an unmeasurable imaginary variable rather than a measurable physical variable. Climate science is already strange enough, because it studies averages rather than observations. But this definition of forcing pushes the field into unreality.
Here is the main problem. Under the IPCC’s definition, radiative forcing cannot ever be measured. This makes it impossible to falsify the central idea that the change in surface temperature is a linear function of the change in forcing. Since we cannot measure the forcing, how can that be falsified (or proven)?
It is for this reason that I use a slightly different definition of the forcing. This is the net radiative change, not at the troposphere, but at the TOA (top of atmosphere, often taken to mean 20 km for practical purposes).
And rather than some imaginary measurement after some but not all parts of the climate have reacted, I use the forcing AFTER all parts of the climate have readjusted to the change. Any measurement we can take already must include whatever readjustments of the surface and tropospheric temperatures that have taken place since the last measurement. It is this definition of “radiative forcing” that I used in my recent post, An Interim Look at Intermediate Sensitivity.
I don’t have any particular conclusions in this post, other than this is a heck of a way to run a railroad, using imaginary values that can never be measured or verified.
w.
Mack says:
December 17, 2012 at 5:35 am
Mack, I’m sorry, but that abusive rant just cancelled your vote with me. I have no time to deal with jerkwagons.
Buh-bye, don’t let the door hit you on the way out. You certainly may talk with others here, but your conversation with me is cancelled because of your sudden storm of extreme dickishness.
w.
Ryan says:
December 17, 2012 at 3:58 am
What part of “global 24/7 average” are you not following? We’re not talking about instantaneous sun at the equator, we’re talking about the global oceanic energy balance.
w.
Willis: Sorry you are not right. When you are measuring the IR you are not measuring the radiated energy from the desk, say, to the thermal imaging camera. You are measuring the infra-red energy that WOULD flow if the thermal imaging camera was at -273Celsius (i.e. absolute zero). So no, it is not an energy you can sense. There is no net energy transferred from the desk to you, for instance, even if the measurement tell you that it is emitting 400W/sqm. There is a small amount of net energy transferred from you to the desk because you are ever so slightly warmer, but it would really be negligible. Similarly there can be no net transfer of photonic energy from the ocean to the air if the air is already at the same temperature, otherwise this would violate the laws of entropy.
TimTheToolMan says:
December 17, 2012 at 5:11 am
OK, so you agree that the ocean is in fact absorbing the energy, and that the energy is in fact subsequently being lost again in various forms … but then you go on to say:
Look, you have agreed that the ocean is absorbing the energy. As soon as it is absorbed it turns into heat … but now you claim that all that added heat doesn’t change the temperature at all.
Energy can’t be destroyed. Every bit of the DLR that you agree is absorbed by the ocean is turned into heat.
You seem to think that that heat does nothing because at equilibrium, an equivalent amount of heat is being lost … but if we took the DLR away, the ocean would cool rapidly and the mixed layer would end up at a much cooler temperature.
So to summarize, it seems that you agree with me that:
1. The ocean absorbs DLR.
2. The ocean ends up warmer with the DLR than it would be without it.
w.
PS—Now that you have come out of the closet and joined the dark sidy by agreeing that the ocean indeed does absorb DLR, watch and see how fast your friends evaporate …
PPS—Your contention. that the amount of energy added to the ocean is rapidly being lost, doesn’t meant that the DLR doesn’t warm the ocean. To understand why, consider, for example, a rock sitting in the sun. The rock is basically at thermal equilibrium.
Note that this is identical to the situation you describe with the DLR in the ocean. The amount of energy added to the rock by the sun is being constantly radiated away. So just as with DLR and the ocean, the rock doesn’t warm.
Where your logic goes off the rails is where you interpret that situation (the amount of energy entering the system is equal to the amount leaving, rock and ocean not warming) as meaning that the sun doesn’t warm the rock, or that the DLR doesn’t warm the ocean. It doesn’t mean that at all. Yes, amount of energy leaving the rock equals the amount entering, just like with DLR and the ocean. But the sun is still warming the rock, and DLR is still warming the ocean.
To see that, just remove the sun. The rock cools. Same is true of DLR and the ocean.
The 340 comes from DLW but it doesn’t go any deeper than the skin. It is cycling so fast that in a quantum sense it is the same energy. Like cycling money between your checking to savings accounts and wondering why you’re still not broke. The small (@ur momisugly 10%) losses from the eddy have been more than compensated for during the satellite era by incoming SW.
1. The ocean absorbs DLR.
Correct.
2. The ocean ends up warmer with the DLR than it would be without it.
Wrong. Because the ocean is emitting at the same rate, being as it is at the same temperature as the air from which it is receiving radiated heat. There is no net flow of radiated heat from ocean to air at the boundary between the two. They are at the same temperature due to conduction. Conduction drives the process to the ocean and air until they are at the same temperature, and then the net radiation in both directions cancels out. In entropy terms they are at the same levels of disorder already due to conduction, so further changes in disorder due to radiation cannot occur.
“To see that, just remove the sun. The rock cools.”
The sun is much hotter than the rock, so it can heat the rock. The air is not much hotter than the rock, so it cannot heat the rock. In any case, the hot rock is busily heating the air by conduction until the two are the same temperature. If the rock is colder than the air it will remove heat from the nearby air until they are at the same temperature. Once this happens radiation cannot play a part at all.
Willis: Last comment for the evening. Do you appreciate that just because the atmosphere might be emitting 340W/sqm this only is relevant for a black body at -273Celsius? I.e. only a black body at -273Celsius can absorb this power? The Earth is not black body at -273Celsius, therefore it cannot absorb 340W/sqm. The figure of 340W/sqm is almost completely irrelevant. Deep space is at -273Celsius so losing the heat to space it is relevant, but not for the Earth.
Watts are a rate of heat transfer. If I have two bodies at the same temperature I don’t get a heat transfer so I don’t get any Watts to measure. Period. Doesn’t matter if it is conduction or radiation.
Ryan says:
December 17, 2012 at 7:16 am
No, Ryan, the desk is not “radiating at 400W”. That statement is scientifically meaningless. Come back when you have figured out why, and we can continue the discussion.
w.
Willis:
At 6:47 on 12/16 you wrote:
“Well, yeah … except that one of them is in the desert and one is not. As a result, they have very different responses to downwelling IR. There is an interesting discussion of these issues here.”
Well, as you say, “well, yeah…” The link doesn’t work so I don’t know what you are getting at. My point is exactly that one place is a desert and the other one is not!! Why is the desert so much hotter than the humid area, despite having only 1/4 the amount of the magic GHGs??
Please check link as I would certainly like to go there. I’ve been bringing this same issue up for about 5 years now, and still have not had any success in reconciling this very simple empirical observation with the postulated radiative GHE.
Thanks!
[Link fixed, thanks. -w]
Willis: ‘You measure another physically real and measurable signal in the same band. They are about equal. As you would imagine, the difference between them is about zero.
Your conclusion?
Your conclusion from the fact that they are equal is that the signals that you measured are imaginary. They are not real. They do not contain energy.
You realize how crazy you are sounding?’
I am not mad, just a rather better physicist than most..Climate science is full of people who look at Stefan-Boltzmann and imagine they know everything. So let me explain things in a different way.
Your desk and you sofa are in radiative equilibrium. If you were to measure the energy arriving at a pyrgeometer sensor between them over 360°, it would be zero.
Now put a metal shield between the sensor and the desk. The pyrgeometer signal immediately jumps to the temperature signal for the sofa, the S-B level in a vacuum. But there is still no radiative transfer between the desk and the sofa so there is no energy flow from the pyrgeometer sensor to the sofa despite the output meter for a pyrgeometer being in units of power.
Do you get it now? Just because the pyrgeometer displays W/m^2, that signal is only true for transmission to absolute zero. The only reason you detect it is because the device shields the signal from the other direction. <It is an artefact which does not exist without the shield in place.
This most basic failure to understand what a pyrgeometer measures has meant climate science is based on an entirely false premise and has been so for 50 years because the Meteorologists and now climate scientists, even mainstream physics in poor institutions are taught false science.
Most of the IR energy in Trenberth’s Energy budget does not exist.
If anyone else cares to comment on this please do because I must ram this message home; climate science has fallen at the first hurdle and the alchemists in it are beavering away repeating the same mistake over and over again.. That is the real definition of madness – at least I vary my teaching approach!
Ryan says:
December 17, 2012 at 9:25 am
Man, you are a regular font of misinformation.
When you are measuring IR, you are measuring IR, nothing else. You can re-baseline your IR measurements all you want, you can convert them into temperature in C or in F, but you are indeed measuring the radiated IR energy from the desk.
I also note that you don’t seem to understand that the temperature of the camera doesn’t change the flow of IR from the desk. The desk doesn’t know what the temperature of the camera is, it radiates the same amount of IR regardless of the temperature of the camera.
In other words, what you call “the infra-red energy that WOULD flow if the thermal imaging camera was at -273Celsius” is exactly the same as the amount of energy that WOULD flow from the desk if the thermal imaging camera was at room temperature.
w.
Ryan says:
December 17, 2012 at 10:02 am
Ryan, please, I beg of you, quit while you are behind. You are making a fool of yourself. Almost none of the statements in those two paragraphs are true. Stop posting, put down the mouse, and nobody gets hurt … then buy yourself a thermodynamics text and learn some science before you post again. It’s painful watching you flail around.
I gotta admit, though, I doubt that you could top this particular piece of misinformation:
I can only shake my head in awe at the massive stock of scientific misunderstanding that you’ve managed to pack into that one short sentence.
w.
One must also account for the observation that the oceans continued to warm after 1997 without wayming the atmosphere. DLR by definition is absorbed by the atmosphere and would warm it equally. Further, one must account for the crazy quilt distribution of ocean surface warming and cooling Bob Tisdale has shown.
AlecM, I am perfectly comfortable with superposition where you isolate the effect of multiple independent sources and sum them. It’s a little more complex when the sources are dependent, but we have a strategy for that too…small signal analysis with preset initial conditions. Weather and climate are state machines where the next state is determined by input signals and the recorded history. I wish, like an academic, I could simply invent forcings and transfer functions to suit my pet theory, but sadly, as an engineer, I’m bound to physical reality. Greenhouse gases increase the Earth’s surface temperature by an average of 33C. Don’t worry about how that’s thermo-mechanically possible, just take their word for it.
kencoffman: greenhouse gases do not cause the Earths temperature to rise by 33K. That was the first big scam of Hansenkoism/Houghtonism!
This is because adiabatic dry LR, Cp/g, is independent of the gas and because there is no mechanism for CO2 to increase water vapour concentration, there is no link with moist LR.
The real GHE is ~ 9 K, the remaining 24 K from gravitational potential energy. The 9 K is the heating of the surface because emissivity falls as GHG thermal emission switches of specific wavelength bands!
AlecM,
You’ve really managed to confuse yourself on the whole issue of Poynting vectors and Poynting’s theorem. It’s a perfectly good way of analyzing electromagnetic waves to find the net flow of energy through a location, and the work done on charges in that location, and the change in energy density at that location. Energy can be radiated by an object while it simultaneously absorbs radiant energy from elsewhere; add these up and you’ll get the net energy gained or lost. If you work with energy, that’s a scalar. If you want to work with Poynting vectors, you can do so; it’s not that useful. But, recognize that for for IR, the emitted and absorbed radiation do NOT cancel each other to leave only their vector sum. The vector sum will give the amount and direction of the NET energy flow at some point, including any work done on electric charges. But that doesn’t negate the components. By the same token, if you deposit your paycheck and pay your rent, and then balance your checkbook, that does not mean that your rent is suddenly unpaid and your paycheck was cut; it just tells you how much is left over for other things.
Waves can add up and cancel; that’s destructive interference. They can also add up and reinforce, with constructive interference. Vector sums of electric fields are useful for this; but if you take the cross product of electric and magnetic fields to get the Poynting vector, you lose polarization information, and can’t analyze interference. Also, you’d need phase information, given by path length differences. Besides that, the Earth’s surface and atmosphere are not going to demonstrate interference anyway; as extended, thermal sources, they don’t exhibit the necessary spatial and temporal coherence.
Poynting vectors are great for anyzing the interactions of EM waves and conductors. But for heat transfer by IR, you really need to start with an outlook based on quantum physics. When IR is emitted or absorbed, this is the interaction between molecules and photons. Only rarely is it helpful to consider the IR as an EM wave interacting with wires or other configurations of conductors. So, the Poynting vector approach isn’t all that useful for heat transfer by IR. It’s still valid, as long as you don’t go tripping yourself up by confusing the vector sum of Poyning vectors at a point with the actual propigation of waves beyond that point, or confusing time-dependent vs. time-independent Poynting vectors, or similar confusions.
Here’s somthing to sum it up:
AlecM says:
December 17, 2012 at 1:00 am
No, both energy flows are real. IR from the surface can transfer energy to the atmosphere; IR from the atmosphere can transfer energy to the surface. Note, I said “transfer energy,” not “warm.” It’s only a warming process if the net heat transfer into an object is positive. But any object that radiates without absorbing at least an equal amount of radiation, will cool.
All energy flows can transfer heat, but only NET energy flows can give NET heat transfer. So, in the above, the net energy flow represents the net heat loss by the ocean, which is given by the difference between IR emitted upward and downward IR absorbed.
If you say that “the problem with this whole analysis is that they physicists don’t understand the physics,” then you’d better be a world-class physicist yourself. Otherwise, you probably missed something.
JazzyT: for a collimated beam, the Poynting Vector is identical to the Planck Irradiance Function at that wavelength.
The vector sum of the PVs UP and Down is simply a wavelength dependent version of the S-B1 – S-B2 calculation………..
JazzyT says:
“If you say that “the problem with this whole analysis is that they physicists don’t understand the physics,” then you’d better be a world-class physicist yourself. Otherwise, you probably missed something”.
So what is a ‘World Class Physicist’ ? Is It some-one who has discovered a ‘New Law’ or some-one who is Popular for reciting ‘Old Laws’?
What is your definition of ‘World Class’?.
Just curious.
I also note that you don’t seem to understand that the temperature of the camera doesn’t change the flow of IR from the desk. The desk doesn’t know what the temperature of the camera is, it radiates the same amount of IR regardless of the temperature of the camera.
In other words, what you call “the infra-red energy that WOULD flow if the thermal imaging camera was at -273Celsius” is exactly the same as the amount of energy that WOULD flow from the desk if the thermal imaging camera was at room temperature.
If the camera was at a temperature lower than the desk energy would flow in the direction of the camera. This would be an extremely small amount of energy as the desk is radiating in other directions proportional to the area that the desk “sees”.
If the camera were hotter than the desk then energy would flow in the direction of the desk, proportional to the area that the camera sees, also providing that all other energy sources are at a lower temperature than the camera.
This is just basic thermodynamics.
Thuswise, if the ocean is warmer than the sky/atmosphere it is radiating toward, it will radiate energy. It does not matter how much downwelling IR there is, from CO2 or a cloud, if the temperature of the ocean is greater than what it is looking at it will radiate energy and thus cool. It will also conduct energy away through molecular interaction with the atmosphere. There will also be convection that will speed the process along. However, to answer your question is that in order for the ocean to freeze, enough energy at the surface has to radiate away so as to bring the temperature at the surface down to freezing at -2c. Even then 80 more calories per cubic cm of energy has to radiate away in order to remove enough energy to support the phase change from water to ice.
The ocean, if its temperature is less than the sky/atmosphere, will absorb energy from the atmosphere/sky. This is just basic thermodynamics.
In the Arctic and Antarctic there is a phenomenon called flash freezing whereby the rough water is continually radiating energy away due to the greater surface area of the water. The temperature can go well below -2c at the surface of the water. Then when the wind dies, tens of square kilometers of water will freeze (phase change to ice) in seconds. Google this, there are videos of it out there some where.
Willis Eschenbach says, December 17, 2012 at 12:24 am:
Greg, […] I see that in fact you agree that everything radiates.
It appears that you believe, however, that when radiation from something cooler is absorbed by something warmer than the spot where the radiation originated, no energy of any kind is transferred to the warmer object.
Is this in fact your belief? And if so …
[…]Put a 100-watt incandescent bulb in a fixture, […] Me, I can do it as a thought experiment, I don’t need to build the apparatus to be clear about what will happen.
========================================================
No, Willis, there was absolutely nothing in my comments that suggested what you said about my “belief”. But nevertheless thank you for this nice example of a straw-man argument.
You “thought experiment” is only an illustration of how you think or (want to make people to believe) how things work. It is not real, it is a product of fantasy and not a scientific argument at all. Your assertion about “NET” you made previously is not science, Willis, it is a fiction, because unproven experimentally. At best you can call it an “experimentally unproven hypothesis”, but not a scientific fact.
The fact that a colder body radiates in a warmer body’s direction ALONE does not prove any particular effect on this warmer body including effect on the warmer body’s TEMPERATURE.
Apparently, neither you nor warmists I talked to on this and other blogs can present a REAL experiment confirming that notion about “NET”. Which inevitably leads to the conclusion that there has never been one and the whole notion is just a fiction.
Yeah, Willis calls it a day with me because he can’t handle the kitchen heat.
A slight improvement in the wording on my last posting to him Dec.17th 2012 @ur momisugly 5.35 am……..
“Sort of one foot in reality and the other in an AGW fantasy” better read as…….
“Sort of one foot in reality and the other in a model of AGW fantasy”
These academic teaching twats drawing pictures of the sun and earth on the blackboard fail to realise they are already modelling. They fail to realise they are in a classroom and not in the real world making real observations and taking real measurements.
Science thus becomes abused …and Willis here is still abusing it.
Mack says:
December 17, 2012 at 4:58 pm (Edit)
Oh, please. I’m unable to make a dent in your lack of knowledge, so I don’t plan to try any further. Your assertions are not simply un-physical, they are a-physical. Please re-read what JazzyT says above. Truly, you don’t understand what you are talking about.
w.
denniswingo says:
December 17, 2012 at 1:57
Thanks, dennis. I’m not sure if we disagree or not. I think the difference is you are referring to the net energy flow while I am also referring to the individual energy flows that are measured in order to determine the net energy flow. Let me try again.
The desk does not know the temperature of the camera. It radiates in all directions. It radiates about the same amount whether the camera is cold or hot.
You are correct that if the camera is colder than the desk, there will be a net flow of energy from the desk to the camera. But this is NOT because of an increase in the energy flow from the desk to the camera. That stays the same, because the temperature of the desk stays the same.
To the contrary, it is because of a decrease in the flow of energy from the camera to the desk. Because the camera is now cold, it radiates less energy.
Because the flow of radiated energy from the camera to the desk is now smaller than the flow of radiated energy from the desk to the camera, the net flow of energy (Q1 minus Q2) is from the desk to the camera. As you point out, net flows of energy always go from warm to cold.
It’s not just a good idea.
It’s the Law.
w.
I thought you were not talking to me Willis,
Trenberth btw is a kiwi and “works” in the USA. I too am a kiwi an as far as I’m concerned you can b— well keep him.