Without anything real to feed on because of deep snow, deer are now starving to death...IPCC climate alarmism is based on a climate sensitivity of 3 C from doubled CO2, presented as the result of feedbacks starting with an initial value of 1 C.
In a survey of IPCC climate science, (former) IPCC scientist Judith Curry has now come to the basic question of Climate Feedbacks:
- Everybody talks about climate feedbacks, but what are they, really? And where did the expression ΔTs = λRF actually come from?
- After two decades of wrestling with this issue, I’m not sure how useful the concept of “feedback” is in the context of the climate system.
- We already saw what kind of trouble we can get into on the thread on CO2 no feedback sensitivity, which is supposed to be the easy part of the problem.
- The problem flat out isn’t linear, and attempting to do a nonlinear control theory analysis is pretty hopeless, as illustrated by the Aires and Rossow paper.
- At best, it seems like the concept is useful as a conceptual aid in thinking about a complex system. Various metrics like ΔTs = λRF or the partial derivatives may have some use in comparing climate models with each other or with observations, but it may not say much about feedback.
- So is this concept useful? If not, can it be salvaged?
- Or are there better ways to try to understand the whole system, something from dynamical systems theory, entropy extremals, etc?
We read that Curry poses questions but we see nothing in the direction of answers.
Curry asks the logical question: If now both the sign and magnitude of feedbacks are
impossible to determine, why was the concept introduced at all?
Because it served IPCC climate alarmism, of course, but there is one important element to understand: Feedbacks need something to feed on, an initial perturbation which can be magnified by positive feedback. So what was then the initial perturbation and how could it be identified by IPCC if nothing else could?
The answer is given in my recent post Definition vs Axiom and Consensus in Climate Science
showing that the initial value to feed on by IPCC is stated to be 1 C, referred to as no-feedback climate sensitivity.
So how is then the initial value of 1 C as no-feedback climate sensitivity determined? By experiments? No, that is impossible. By a theory starting with some assumptions which can be verified? No, nobody knows such a theory.
What remains is to take 1 C as a definition of no-feedback sensitivity to be computed by a
direct application of Stefan-Boltzmann's Black-Body Radiation Law with certain data ("radiative forcing" of 4 W/m2), which invariably gives 1 C.
The advantage of a definition is that full consensus can be reached: It is pointless to question if there are 100 centimeters on a 1 meter. It is pointless to question a no-feedback climate sensitivity of 1 C computed from Stefan-Boltzmann's Law with certain data. That would be like questioning that there are 200 centimeters on 2 meters.
IPCC thus can safely state that there is full consensus about a no-feedback climate sensitivity of 1 C, because it is a definition.
So, a definition is wonderful in the sense that full consensus can be reached as concerns its validity. But the full consensus and absolute truth of a definition does not come without a serious drawback: A definition says nothing about reality.
If we understand this, we understand that the IPCC feedbacks have nothing real to feed on, and
thus cannot say anything about any reality. Curry has understood this, maybe. Anyone else?
For example, what about Lindzen and Spencer? Are they happy to twist, like IPCC, a definition into a potentially alarming physical fact of 1 C, and then have to argue that negative feedback can diminish it to a harmless 0.5 C, using an argument that can easily be questioned? Is this clever? Is it science?
It must be possible for a scientist to understand if a certain statement is a definition, which is true by its construction independent of any reality. Or if it is a statement about reality which may be true or false depending on the reality and therefore can be questioned, because perceptions of reality can differ and thus possibly prevent full consensus.
Inlägg
Claes, have a look at the Miskolczi paper:
SvaraRaderahttp://met.hu/doc/idojaras/vol111001_01.pdf
It seems that also M uses backradiation, in the quantity E-D, while S-G is the full SB radiation flux. Unphysical according to my analysis.
SvaraRaderaClaes, One can argue about a definition if it is not correct. The Stefan-Boltzman equation is only applicable to black bodies and when there is heat transfer between two bodies it is only applicable in a vacuum. If there is a fluid between the two bodies, there will be boundary layers which change the surface temperatures, there will be heat transfer by convection and the fluid will absorb some energy by radiation. The emissivity which must be introduced with real surfaces can vary with temperature. The boundary layer properties are affected by the movement of the fluid.
SvaraRaderaOne thing that has been over looked (deliberately?)is that CO2 only absorbs radiation in very narrow wavelength ranges. Molecules of CO2 are not black bodies. The absorptivity/emissivity is very very small and depends on the temperature of the source. I have calculated it using the Hottel equation (which was determined from measurements in heat exchangers) at 0.007. The assumptions of 4W/m2 and 1C are nonesense and unreal.
Here is a paragraph from a forum post at
SvaraRaderahttp://www.physicsforums.com/showthread.php?t=252066&page=3
The poster first introduces the "IR window" in Earth's atmosphere, then goes on:
"Outside the window, where the cloudless atmosphere is opaque to IR, the propagation of heat from the land-sea surface to the lower skin of the atmosphere, and through the atmosphere except in its upper reaches, is described by the diffusion limit of the radiation transfer equation (Mihalas and Mihalas 1984). Fourier's law of heat diffusion reigns here. Though very widely customary, it is not good physics to try to speak or think here of "radiative transfer" as distinct from conductive-convective-evaporative transfer. The radiative part of the heat transfer is much better thought of as part of the diffusion-conduction. Both ponderable matter and radiation share inseparably in the conduction of heat. The mean free path of the IR "single photons" is some tens of meters, a distance over which the temperature of the air changes only a little, because of convection. It is thus futile to think separately of "radiative transfer" from the land-sea surface outside the window. In other words, the commonly touted story of "back-radiation", from the bulk of the atmosphere to land-sea surface, is futile, poor physics, confusing or misleading, practically meaningless outside the window. Outside the window, the rate of transfer of heat from land-sea surface to lower atmospheric skin is directly proportional to the local temperature gradient, as expressed by the Fourier heat diffusion law, and one can forget a separate radiative transfer here."
It seems to me, a physicist, easy to understand why "backradiation" is wrong-headed, yet so many in climate science are deceived. Such entrenched incompetence, throughout the whole field, is like a rare nugget, or (a better simile) a great malignant tumor, amazing to behold. The public cannot believe an entire science can be wrong today, no matter how good are the credentials of the competent critic. But I try to see the glass as half full, and am pleased "Slaying the Sky Dragon" appears to be getting attention, from those willing to think forbidden thoughts. People don't know me, so unless they already disbelieve the consensus they dismiss me without real thought. I haven't seen any sign from Curry that she has cast off the mirage of backradiation. She seems to want to redefine the "greenhouse effect" simply as the absorption of IR in the atmosphere, without confronting the illegitimacy of backradiation. I tried to tell her the issue was whether "greenhouse gases" warmed the atmosphere by absorption of direct solar IR radiation, or by absorption of surface IR emissions, but I doubt I got through to her.
Curry is searching for a "greenhouse effect", but does not seem to know where to look or who to ask. Strange since AGW is supposedly derived from this effect.
SvaraRaderaClaes, regarding the cold winter. Please read:
SvaraRaderahttp://www.smhi.se/forskning/varfor-kom-vintern-sa-tidigt-1.13793 which ends:
"Just nu är 2010 ett av de varmaste åren globalt sett."
But what are the deer saying? 2010 one of the warmest years?
SvaraRaderaFunny... Please don't mix up weather and climate.
SvaraRaderaI agree that M is somewhat stuck in the "greenhouse paradigm", however i think he might be up to something rather important if the different fluxes are given appropriate physical interpretations. For example, since the atmosphere is a gravitationally bounded system there must be a constant downward force acting on the gas which ought to have some consequences. I think that what he discovered was that the total IR-flux absorbed by the atmosphere according to GE happened to equal the total potential energy of the gas. Is this a coincidence?
SvaraRaderaSeems to me that radiation does not couple with gravitation, since Maxwell's equations behind radiation do not contain gravitational forces. Or?
SvaraRaderaTrue, gravity is not included in Maxwells equations. However, to me the radiation cartoons of IPCC looks very similar to a freebody diagram of a mass at rest on a surface. In other words, the arrows could be interpreted as forces. Indeed, light with a certain direction which is absorbed is nothing else than a force which physicists should know.
SvaraRaderaSo, when M observes that the greenhouse equations are tuned so that the total absorbed IR-energy equals the total potential energy of the atmosphere, there could be something interesting hiding in that observation. I think at least people should take a moment to reflect upon it.
Here is some further discussion:
http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.2980v2.pdf
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