In Their Own Words: The IPCC on Climate Feedbacks
by Roy W. Spencer, Ph. D.
Despite the fact that the magnitude of anthropogenic global warming depends mostly upon the strengths of feedbacks in the climate system, there is no known way to actually measure those feedbacks from observational data.
The IPCC has admitted as much on p. 640 of the IPCC AR4 report, at the end of section 8.6, which is entitled “Climate Sensitivity and Feedbacks”:
“A number of diagnostic tests have been proposed…but few of them have been applied to a majority of the models currently in use. Moreover, it is not yet clear which tests are critical for constraining future projections (of warming). Consequently, a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed.”
This is a rather amazing admission. Of course, since these statements are lost in a sea of favorable (but likely superfluous) comparisons between the models and various aspects of today’s climate system, one gets the impression that the 99% of the IPCC’s statements that are supportive of the climate models far outweighs the 1% that might cast doubt.
But the central importance of feedbacks to projections of future climate makes them by far more important to policy debates than all of the ways in which model behavior might resemble the current climate system. So, why has it been so difficult to measure feedbacks in the climate system? This question is not answered in the IPCC reports because, as far as I can tell, no one has bothered to dig into the reasons.
Rather unexpectedly, I have been asked to present our research results on this subject at a special session on feedbacks at the Fall AGU meeting in San Francisco in mid-December. In that short 15 minute presentation, I hope to bring some clarity to an issue that has remained muddied for too long.
To review, the feedback measurement we are after can be defined as the amount of global average radiative change caused by a temperature change. The main reason for the difficulty in diagnosing the true feedbacks operating in the climate system is that the above definition of feedback is NOT the same as what we can actually measure from satellites, which is the amount of radiative change accompanied by a temperature change.
The distinction is that in the real world, causation in the opposite direction as feedback also exists in the measurements. Thus, a change in measured radiative flux results from some unknown combination of (1) temperature causing radiative changes (feedback), and (2) unforced natural radiative changes causing a temperature change (internal forcing).
The internal forcing does not merely add contaminating noise to the diagnosis of feedback – it causes a bias in the direction of positive feedback (high climate sensitivity). This bias exists primarily because forcing and net feedback (including the direct increase of IR radiation with temperature) always have opposite signs, so a misinterpretation of the sum of the two as feedback alone causes a bias.
For instance, for the global average climate system, a decrease in outgoing radiation causes an increase in global average temperature, whereas an increase in temperature must always do the opposite: cause an increase in outgoing radiation. As a result, the presence of forcing mutes the signature of net feedback. Similarly, the presence of feedback mutes the signature of forcing.
The effect of this partial cancellation is to result in diagnosed net feedbacks being smaller than what is actually occurring in nature, unless any forcing present is first removed from the data before estimating feedbacks. Unfortunately, we do not know which portion of radiative variability is forcing versus feedback, and so researchers have simply ignored the issue (if they were even aware of it) and assumed that what they have been measuring is feedback alone. As a result, the climate system creates the illusion of being more sensitive than it really is.
One implication of this is that it is not a sufficient test of the feedbacks in climate models to simply compare temperature changes to radiation changes. “This is because the same relationship between temperature and radiation can be caused by either STRONG forcing accompanied by a large feedback parameter (which would be low climate sensitivity), or by WEAK forcing accompanied by a small feedback parameter (which would be high climate sensitivity).”
Only in the case of radiative forcing being either zero or constant in time – situations that never happen in the real world – can feedback be accurately estimated with current methods.
Our continuing analysis of satellite and climate model data has yet to yield a good solution to this problem. Unforced cloud changes in the climate system not only give the illusion of positive feedback, they might also offer a potential explanation for past warming (and cooling). [I believe these to be mostly chaotic in origin, but it also opens the door to more obscure (and controversial) mechanisms such as the modulation of cloud cover by cosmic ray activity.]
But without accurate long-term measurements of global cloud cover changes, we might never know to what extent global warming is simply a manifestation of natural climate variability, or whether cloud feedbacks are positive or negative. And without direct evidence, the IPCC can conveniently point to carbon dioxide change as the culprit. But this explanation seems rather anthropocentric to me, since it is easier for humans to keep track of global carbon dioxide changes than cloud changes.
Also, the IPCC can conveniently (and truthfully) claim that the behavior of their models is broadly “consistent with” the observed behavior of the real climate system. Unfortunately, this is then misinterpreted by the public, politicians, and policymakers as a claim that the amount of warming those models produce (a direct result of feedback) has been tested, which is not true.
As the IPCC has admitted, no one has yet figured out how to perform such a test. And until such a test is devised, the warming estimates produced by the IPCC’s twenty-something climate models are little more than educated guesses. It verges on scientific malpractice that politicians and the media continue to portray the models as accurate in this regard, without any objections from the scientists who should know better.
Given that the clouds are moving, transferring energy from one place to another (generally equator -> poles) I’m also not clear on what is being measured from a static position in the stream. The downward energy (LW) flux being measured at that point is from elsewhere (outside our arbitrary column). Energy is arriving and leaving the column horizontally as well as vertically. Not at all clear on how the two components are separated in any calculations.
The diagram with the single op amp is much too simple to reflect the real situation. You need long time delays to allow tropical pacific water to reach the Bering Strait and then you need to determine what the polar vortex is doing to compute how much it will rain in Seattle.
Determining a short-term response to temperature changes in the presence of unforced natural radiative changes that “just happen” seems futile unless the longer term mechanisms that cause the “happenings” can be fully described and modeled. That may well take place, but until then Miskolczi’s constant tau assumption is the best guess I know of. How does incoming SW tau vary? With what? Same for outgoing LW tau? Get a good handle on these and you have a good handle on climate.
Re Measurements of the Radiative Surface Forcing of Climate
Quote from Abstract: “This experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming”
Is it normal to spit on the skeptics already in the Abstract? Smell of Catlin with preconceived agenda.
To the article:
The earth’s climate system is warmed by 35 C due to the emission of downward infrared radiation by greenhouse gases in the atmosphere..
IMO this is the basic mistake. Earth climate system is warmed by mere existence of the atmosphere (oceans), which keeps and distributes the day (summer) heat. If I cover my face against the night sky, I do not feel lack of warmth like when doing so during the day against solar radiation. The atmosphere radiates, because it is warm; it is not warm because it radiates.
Fig 1 shows measured winter spectra of greenhouse gases. How come there is no sign of water vapor emission line? If absorbtion spectrum = emission spectrum, the thick line on the left between 5-8 microns, assigned to CO2 is actually H2O line.
Fig 2 shows measured summer spectrum, but again H2O is not assigned to any of the spectral lines.
http://z.hubpages.com/u/1293007_f520.jpg
The flux measurements presented in Table 2 provide important experimental verification of the driving radiation that is responsible for global warming.
First, the Table 2 does not contain water vapor flux (by far the biggest contributor to downward LW flux). Second, it does not provide anything; that slightly increased LW radiation will be sucked up by 70% of earth surface – oceans – just to increase evaporation a bit. Third, if colder regions should more readily react on increase of CO2 because of low humidity, how come that Greenland was colder in 2000s than in 40ties, its temperature being now on the 1920 level and falling down again?
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=431042500000&data_set=1&num_neighbors=5
Something is driving those temperatures up and down, but those downward fluxes obviously do not.
There is some argument to suggest that tropospheric water vapour has already increased by several percent; hence, the corresponding flux contribution may need to be included, but this effect is beyond the scope of current models.
Not the case; even IPCC AR4 says that whether it has increased or not “is a subject of significant debate”. Radiosonde measurements show drop of moisture in the upper troposphere and ERBE/CERES satellite measurements of OLR also show weakening of ability of “high clouds” (=upper troposphere humidity) to retain the outgoing radiation.
From Table 4 it is evident that the actual greenhouse radiation has increased by over 3.5 W/m2 since pre-industrial times, or by about 2.3% of the total greenhouse radiation.
Until I see long-term measurement data from globally distributed measuring locations since 1850, it is still assumption based on modeled fluxes in 1850, while estimating the biggest player – water vapor – has been kept constant. In reality, the upper tropospheric humidity, which gives cca half of water vapor downward flux, has actually decreased during last decades.
Last, more than half of the earth surface is covered by clouds, which have no IR window like H2O/CO2 and mercilessly absorb and re-radiate all outgoing radiation. Effect of clouds on outgoing radiation (and on incoming as well) is therefore much more significant, does not matter how it really contributes to that 33K myth.
These are measured fluxes during clear sky day:
http://www.srrb.noaa.gov/cgi-bin/surf_check?ptype=gif&site=desr&date=17-jun-2008&p1=dpsp&p5=dpir&p6=upir
It is interesting, that atmosphere radiates constant downward LW radiation, not depending how much upwelling LW it is receiving. It does not behave as an obstacle for outgoing LW radiation.
http://www.srrb.noaa.gov/cgi-bin/surf_check?ptype=gif&site=desr&date=12-jul-2008&p1=dpsp&p5=dpir&p6=upir
Cloudy day: clouds block solar radiation, cooler earth surface radiates less upwelling radiation, but downwelling radiation now clearly reacts, being effectively absorbed and re-emitted by clouds. Overall local increase is, however, not too significant.
But if we want to play the 33K game, lets go: Kiehl-Trenberths LW downward flux of 324 W/m2 causes +33K. Calculated increase of 2.4W/m2 (40% on the way to CO2 doubling) is equivalent to 0.24K increase in temperature, with no changes in water vapor or clouds. Doubling gives puny 0,4 K, the same number which Miskolczi or Lindzen came to from different directions.
The whole study looks rather junk to me: funded by Canadian Foundation for
Climate and Atmospheric Science, with preset goals – to “effectively end the argument by skeptics”. Authors measured flux, by computer model extracted the CO2 flux, in another model they calculated what was the CO2 flux in 1850 and obtained staggering difference of few W/m2. So what?
anna v (21:43:56) :
I think that the recent deconstruction of Lindzen posted here previously stands by itself in refuting the models, because it uses the same definition for models and data of what “change in radiation” and “change in SST”. The models are glaringly inconsistent with the data.
It is important to keep that in mind. Both Lindzen and the AGW modelers can both be wrong. They cannot both be right. If someone wants to argue that Lindzen is not properly measuring the feedback, he or she still has to contend with the fact that his observations contradict the AGW models.
Retired Engineer (19:53:38) :
If the climate really is a closed loop system, it is almost impossible to measure the feedback. You cannot determine the transfer equations without “opening” the loop. Since we have limited, perhaps zero, control over the input to the system, just looking at the output doesn’t reveal much.
It is possible, if you have access to the internal signals, and they are “persistently exciting”. Then, you can do a cross correlation between the inputs and outputs to specific blocks. It becomes increasingly difficult, however, if the blocks are MIMO. And, it goes without saying you’ve got to have a good model, encompassing all significant inputs and dynamics.
I find it amusing that people often refer to climate studies that come out of the climate change industry. Yes, a multi-billion dollar industry at that! Would these same folks quote studies that came out of the tobacco industry? It’s all part of the cognitive dissonance that comes with faith vs. science.
Juraj V. (10:47:58) :
As I indicated in my comment, I share your general disdain for the paper. I was intrigued by the measurements that showed that in the presence of downwelling LW fluxes from H20 over 200W/m2 the CO2 flux was reduced to a rather inconsequential 10.5 W/m2, less than a third of the winter value. This reduced the percent of the total flux attributable to CO2 to less than 4% of the nearly 270W/m2 total in one of the years. Since, the estimates of similar fluxes, in the tropics where global warming is supposed to occur, are greater than than the levels measured by the Canadians, I suspected that if similar measurements could be taken there, it would prove that any contribution of marginal CO2 would be overwhelmed by minor random variations in the H2O component
In classical feedback systems; the forward “gain block” (A) contains a power source that is the energy source that makes it all happen. The feedback network (B) most often consists of passive elements, containing no energy sources; just lossy or storage elements.
But there is no fundamental requirement that that be so. Practical amplifier systems always have gain functions in both directions which are usually not equal; and the feed pack path could contain energy sources.
But then it becomes difficult to sort out which is (A) and which is (B), specially when the magnitudes of (A) and (B) are small.
Modern feedback amplifiers have huge values for (A), and use purely passive and usually linear elements for (B) resulting in an output which deopends only on (B) and changes little, even with order of magnitude changes in |A|.
Climatologists claim that water is a constituent of (B), even though it exhibits the exact same type of (A) like influences that CO2 or CH4 exhibit; plus some unique ones of its own.
I for one do not except the interpretation that water is a feedback that only springs into action when CO2 of CH4 and others occupy the (A) box) but somehow water cannot be in (A).
I say baloney; H2O can do it all by itself and the result would be little differnt without any CO2 or CH4 or anything other than H2O. Well the amount of cloud cover which is around 50% would change somewhat; but I don’t see the total temperature range changing much.
Scott,
Basically you are stating that we know that the current lack of warming can be attributed to the volcanic eruptions which therefore mask the amount of warming that would be occurring had said eruption not take place? Just trying to make sure I understand where you are going with this. It is not to say it did not happen or cannot happen but… that is the equivalent of saying CO2 cannot be the culprit, rather we simply are not having enough volcanic eruptions.
Any amplifier is basically a four terminal network, and in the electronic domain, that network can be characterized by a number of parameters and relationships.
If I define Ein as the Voltage between the input terminal pair.
Eout sa the Voltage between the outpur terminal pair.
Iin as the current flowing into the input.
Iout as the current flowing out of the output.
Then I can also define a Voltage Gain Av = Eout/Ein and also a current gain
Ai = Iout/Iin, and then I can say that Ein = Iin . Zin, and Eout = Iout . Zl where Zin is the input impedance seen looking into the input temrinals, and Zl is the Load impedance being driven by the output.
Now these results are perefectly general properties of any electonic model amplifier.
Some elementary prestidigitation of all of that yields the following:-
Av . Zin = Ai . Zl which is a perfectly general property of an amplifier.
If you weant to apply feedback to such an animal, you have a number of choices. Feeedback normally takes a sample of the output and combines it with the original input signal.
But now we see, that we could sample either the output Voltage, or the output current, and feedback a portion of that. also we have a choice at the input, so we could combine the feedback sample, as either a current added into the input terminals, or as a Voltage added to the input Voltage.
Wouldn’t you know it can can do any or all of those things at the same time.
Generally if you sample the output Voltage, you end up reducing the output impedance of the amplifier (for negative feedback), whereas if you sample the output current the output impendance tends to increase.
You can modify both the input and output impedance with the appropriate feedbacks. And if the feedback sampling elements are frequency dependent; you can make those gains and impedances functions of frequency also for whatever reason you might want to.
Now I am sure that any physical model of the climate system that is represented as a feedback amplifier; would have climate analogs of the electrical parameters of the electronic feedback amplifier; including those impedances.
So now what do you modellers say about the climate feedbacks; are they Voltage feedbacks or Current feedbacks; and do they sum with the input as currents or Voltages; it makes quite a difference to the system impedances depending on which it is.
Now I personally don’t view the system as a feedback system anyhow. I think you have a complex system with many inputs and many oputputs, and these all bear some sorts of relationsships with each other; maybe even some cause and effect relationships.
Water and CO2 are just some of the factors in the system; and I don’t think you can regard either one as simply a feedback sample, let alone decide whether it raises or lowers the outpur impedance of the climate system; which presumably would make the system more stable or more unstable, depending on what the equivalent circuit is.
Just my opinipon of course; not citing any peer reviewed literature to support my view.
What it seems to boil down to is something like this. Leaving aside for the moment tectonic movement over geological time, the ocean and atmosphere as a whole system are balanced on a knife-edge of equilibrium with albedo and solar and cosmic ray influence, established over millions of years.
However at smaller local scales, such as continents and ocean basins, equilibrium is not even approached and dynamic chaos with non-equilibrium pattern formation the order of the day. The system is oscillatory – the term used by Tenuc, “quasi periodic chaotic non-linear” is apt. As with well-known experimental reaction-diffusion systems which display similar behaviour, they can receive periodic forcing (e.g. Milankovich, solar cycles) but also generate spontaneously and intrinsically, travelling waves, moving patterns and oscillations. As discussed on previous posts, in the context of such a nonlinear system, negative feedback is friction or damping and promotes pattern formation, while positive feedback kills off emergent pattern and imposes regular oscillation.
Stephen Wilde has proposed a persuasive scenario in which oceans which hold most climate heat energy, drive climate by an interaction between the periodic forcing they are subject to and (of no less magnitude or importance) intrinsic emergent oscillation and pattern from the ocean basins. (The decadal oscillations are examples of such emergent pattern.) The oceans serve up heat and cold as they see fit, and we on land and in the atmosphere just stand in line to receive it.
Possible intriguing evidence for this is shown in a link from Climate Sanity – a suggestion from the last decade or so that the rate of sea level change (an index of heat movement into or out of the upper ocean layer) is predictive of atmosphere and climate temperature by about one year.
http://climatesanity.wordpress.com/page/2/
However while non-linear dynamics prevail at smaller scales, at the global system the heat budget is finely balanced. This does not however mean instability. The climate and biosphere have remained relatively stable over 4 billion years, withstanding bolide impacts, flood basalts, plate tectonics and a possible nearby supernova among other insults. It has absorbed a 30% increase in solar output over this time without increase in temperature. So no nonsense about sensitivity and runaway feedback from CO2. None-the-less there is an equilibrium of some sort that results in solar oscillations of a miniscule magnitude exerting a forcing influence on ocean heat exchange.
The solar hypothesis of climate has often been overdone and naive versions of it have been justifiable attacked again and again. But like a horror movie end-boss the solar climate influence idea somehow refuses to die.
Climate cant be just the sun – this is equally simplistic and wrong as it being just CO2.
There is an interplay between sun and oceans. The fine balance of the ocean heat budget allows a weak solar oscillation (in fact several oscillations over several timescales) to cause the ocean to alternate between heat-gaining and heat-losing modes. In fact “cause” is the wrong word. The solar cycles influence the ocean heat budget alternations by way of interaction with the ocean’s own intrinsic rhythms. The fine balance and oscillation of the ocean is probably not attributable only to linear equations, but is also an emergent property of the dynamically chaotic non-linear/non-equilibrium system. A strange attractor or a limit cycle.
Control engineering pratice includes “system identification”. This is statistical analysis to estimate parameter values in a parameterissed model of the system to be controlled. We need these for control design.
I hope you’ll forgive a simplified, but slightly technical discussion to support many of the points made above.
Let’s say we want to relate output ‘y’ to an input ‘x’, but we’re stuck with noisy measurements (noise or extraneous input ‘z’). The simplest case is to “identify” fixed constant parameter ‘K’:
y(t) = K.x(t) + z(t)
Ideally, all of the x(t) and z(t) are independent of all other x and z in the two series. With a decent sample size, it is then fairly easy to estimate K.
Things get tricky if there is any correlation between x(t) and z(t). Same if either x or z is autocorrelated (some dependency between the neighbouring values in the series). A simple statistical analysis cannot therefore trace the variation in y to K.x. It could just as easily be variation due to neighbouring values of x or z. Averaging doesn’t remove the bias. We therfore get a false estimate of the value of K.
That’s why I feel very sceptical about estimates of climate sensitivity from (say) single events like Pinatubo. Think of all of those decade-long climate processes – are we supposed to accept that the data is free from autocorrelation?
To finish off, a highly simplified example of a feedback process with a delay period ‘n’ in the feedback loop:
y(t) = A.x(t) + v(t) + B.y(t-n)
y is no longer just a function of x and z, but is a function of the whole history of x and z. Autocorrelation is a consequence of the feedback loop.
So if all we have is some noisy measurements of y and x in a long duration climate process with feedback, it’s not going to be easy to tease an unbiased estimate of a conceptualised climate parameters from the data.
That’s my take on the climate sensitivity estimates we see today.
The thrust of the short article was about the IPCC’s own admission of the feedback being “difficult” to work out, which is a great article topic given the “science is settled” claim. And the feedback model that Dr. Spencer shows is, I’m sure, just by way of illustration.
The real problem is that B (the feedback) is not a constant due to the complex non-linear interactions in 3D of all of the different elements of the climate system. So even if a definitive and accurate test could be done of the “feedback parameter” for the world’s global mean surface temperature in 2008, and B= +0.5 (whatever that means, just a number for illustration), when we do the amazing test again for 2009, B might be -0.6. And in January 2010, B might be 0.1, and so on.
The history of the climate system, being exhibit 1 for the skeptics, seems to clearly demonstrate this.
With no human interaction, the GMST sinks down several degrees and we have an ice age for a period of time, and then, as if out of nowhere, the GMST soars by 5-10 degrees and we have an interglacial. Like in the Eemian interglacial around 130,000 years ago.
Exhibit 1 doesn’t prove or disprove that CO2 didn’t cause the warming between 1970-2000. But it clearly makes the AGW movement uncomfortable as they have been trying to airbursh out the most recent history of temperature changes so that the 20th century and especially 1970-2000 can be called “unprecedented”.
Does CO2 cause warming? Yes. Can we establish how much warming? Yes, it’s simple physics but *only* until we consider feedback, which – my opinion – may never be worked out. That is, the computer models may never be able to establish this feedback.
Because to get an accurate computer model you need:
– accurate and complete equations for all of the processes in the system (ocean currents, salinity, wave angles for working out reflected sunlight, wind vectors, humidity profiles, aerosols impact, cloud formation, rain, hail… ok I missed a few hundred)
– boundary conditions at t=0 (the time we start the model running from)
– finite element analysis computer capable of running the model with these equations at the *spatial discrimination* needed to accurately model the climate
So, even after finding out nos 1 and 2 – and no 1 according to even the IPCC is a major problem because they describe many processes as understood to only a low level of confidence – even after finding them all out, it might be that a computer model needs to be run with gridcells only 100m apart, not 200km that are currently used. (Of course, you will need the boundary conditions for all of these process values at every gridcell – temperature profile with height, wind speed, cloud cover, ocean salinity, vegetation cover, ground type, humidity profile.. plus a few hundred other values)
What is the value that’s needed for this spatial discrimination in the model? Is it 200km? Is it 100m?
We can only know that we’ve achieved it when the model can predict the future. So far they can “predict” the past – as far as GMST is concerned, but I doubt that they get the actual climate system at each grid point – cloud cover, humidity, temperature, salinity, ocean current, wind speed. If they don’t, is the model accurate?
I’m sure the models are useful because they give insight into the processes and their interaction and climate scientists will learn a lot in the process.
But are they useful for predicting the climate in the future? Can they calculate the feedback?
Spencer’s graphic invites the question: where does the power for the amplification of solar radiation (the driving input) come from? It seems that recirculation of thermal energy by the climate system and/or changes in its response characteristics are being confused with true feedback, which always affects the input. How can Earth change solar radiation? Amplifiers and true feedback loops are easy to draw, but difficult to find in inanimate nature. I suspect there are none in the climate system. A complex nonlinear system can be adaptively time-varying without any amplifiers or feedback loops.
“A proof is a proof is a proof.”
My favourite ever quote, by Professor Minister Jean Chrétien.
He never made more sense.
Phlogiston (17:11:39) :
” the ocean and atmosphere as a whole system are balanced on a knife-edge of equilibrium with albedo and solar and cosmic ray influence…
This does not however mean instability. The climate and biosphere have remained relatively stable over 4 billion years, withstanding bolide impacts, flood basalts, plate tectonics and a possible nearby supernova among other insults. It has absorbed a 30% increase in solar output over this time without increase in temperature.”
I would generally term such a system “robust”. I do not see any sense in which it is “balanced on a knife-edge”.
I think you need to separate internal stability from forcing. These cycles do not come about because of some self-sustaining internal dynamic. They are imposed by external forcings. The Sun is external to the system – it is not part of a feedback loop. The Sun couldn’t care less what is going on with the Earth’s climate. Have I misinterpreted what you have said?
Phlogiston (17:11:39)
Thank you.
Apart from a couple of minor terminological quibbles that is a fair alternative summary of my proposals.
It’s nice to see it all sinking in over time. The oceanic contribution to climate change is popping up everywhere these days but it was hardly mentioned less than two years ago.
I don’t see the system as ‘balanced on a knife edge’. Rather the fineness of the balancing act makes the system as a whole ‘robust’ as suggested by Bart (19:30:03).
Short term sensitivity leading to long term robustness is another way of describing it.
Either way the sun and oceans are in control and we are just along for the ride.
The oceans are jealous of their power and use the speed of the hydrological cycle mediated by the latitudinal positions of the air circulation systems to prevent changes limited to the air from usurping their authority.
If extra downward re-radiated infra red energy from extra CO2 cannot add to the ocean energy content then it cannot alter the Earth’s equilibrium temperature. Instead a miniscule change in the rate of energy transfer to space occurs to retain the equilibrium set by the sun and oceans.
I await, with interest, a sensible disproof of what I say. I’ve been waiting for 18 months now.
Bart (19:30:03)
Clearly “Interplay” between sun and ocean is the wrong term, implying a reverse causality between the earth and the sun. Clumsy wording.
What I was trying to get at was the appearance of a fine balance when the ocean heat content is looked at – e.g. Levitus et al 2009 recently found that there was a very finely balanced thermal budget, such that even volcanic / geothermal inputs needed to be considered. However there is a tension or paradox between this fine balance and the robustness of the system as a whole. I conjectured that the system is drawn or attracted to this balanced state by a nonlinear process.
Why do you reject self-sustaining internal cycles? Spencer himself concedes that chaotic nonlinear dynamics have a role in the climate system, and emergent oscillations and patterns are what you get in such systems. They form a major part of what Stephen Wilde proposes in an ocean-driven climate system.
The oceans and atmosphere are not necessarily just passive resonators of external forcings – the possibility of internally generated oscillations and complex waves from nonlinear dynamics is taken seriously by many scientists.
Several people have suggested a disagreement between Lindzen and Choi on one side, and Spencer on the other side.
Yes, they’re right. There’s a disagreement here. Roy wrote about it here:
http://www.drroyspencer.com/2009/11/some-comments-on-the-lindzen-and-choi-2009-feedback-study/
And although I like Richard a lot, and believe that the long-term net feedbacks are negative or close to zero, I agree with Roy, too:
http://motls.blogspot.com/2009/11/spencer-on-lindzen-choi.html
We believe it is not the case that the models predict a reverted (decreasing) dependence of outgoing heat on the temperature.
The main confounding issue when trying to understand climate is the large number of inter-related mechanisms that combine to produce the total effect we (partly) observe. We are also only just starting to realise how the extra-planetary environment has an effect on climate and it would seem that every time a new satellite is put into orbit unexpected events are observed.
Each individual climate processes often has several modes of operation over time, depending on the inputs it receives from related mechanisms – from dead calm to highly turbulent. To cope with this degree of complexity, scientist resort to taking averages at low temporal rates, using low granularity data. This makes a nonsense of trying to understand how things work, and using these broad ‘guestimates’ to try and get accurate forecasts of climate is futile.
Phlogiston (03:51:25) writes:
“The oceans and atmosphere are not necessarily just passive resonators of external forcings – the possibility of internally generated oscillations and complex waves from nonlinear dynamics is taken seriously by many scientists.”
Inasmuch as all the power (forcing) comes from insolation, the climate system is entirely PASSIVE in the technical system-analysis sense. The oscillations/waves are forced RESPONSES of the complex nonlinear system, which lacks the ability to GENERATE power on its own (aside from negligible geothermal sources). It can only store and redistribute/recirculate some of the energy derived from thermalization of insolation. Devoid of independent power sources or amplifiers, it cannot physically implement any bona fide FEEDBACK within the system, i.e., become an ACTIVE system. It can, however, exhibit changing response charateristics as a result of slight variations in forcing, i.e., be a TIME-VARYING ystem.
The lack of grasp of the fundamentals of complex system behavior is what keeps “climate science” in its primitive state. I regret that I cannot take any more time this week to try to clear up the persistent confusion. Cheers!
John S. (09:50:15) :
Phlogiston (03:51:25) writes:
“The oceans and atmosphere are not necessarily just passive resonators of external forcings – the possibility of internally generated oscillations and complex waves from nonlinear dynamics is taken seriously by many scientists.”
Inasmuch as all the power (forcing) comes from insolation, the climate system is entirely PASSIVE in the technical system-analysis sense.
Insolation at what height? Changing albedo changes insolation at sea level. The change in albedo is dependent on the variables at sea level. Your exposition is simplistic, methinks.
Good point. I’m not sure how universal that is, but in servo control, the command is the input, but the power system feeding the servomotor does the lion’s share of the work. This is also true for wrapping feedback loops around amplifiers.
I applaud Mr. Sowell’s take on the problem, as well as Dr. Latour’s. I’ve been pointing out that the climate model has been had a number of control-systems misnomers applied to it for some time now, but the climatologists still insist on borrowing heavily from the systems engineering lexicon without paying much attention to what the various terms actually mean.
“Positive feedback” in this context would mean an exponential increase in temperature, until something went nonlinear to the point where positive feedback was no longer occurring. “Forcing” in this context would mean a “command”, which in the context of world climate doesn’t exist, unless you wish to consider the will of God in the matter. What gets referred to as “forcing” is simply different kinds of nonlinear and unpredictable variation in the feedback loop gain.
As I understand it, anyway. I do know that things are NOT what they are being named.
Luboš Motl (08:23:38) :
Several people have suggested a disagreement between Lindzen and Choi on one side, and Spencer on the other side.
Yes, they’re right. There’s a disagreement here. Roy wrote about it here:
http://www.drroyspencer.com/2009/11/some-comments-on-the-lindzen-and-choi-2009-feedback-study/
And although I like Richard a lot, and believe that the long-term net feedbacks are negative or close to zero, I agree with Roy, too:
http://motls.blogspot.com/2009/11/spencer-on-lindzen-choi.html
We believe it is not the case that the models predict a reverted (decreasing) dependence of outgoing heat on the temperature.
There have been reports in the peer review literature that the models violate the second law of thermodynamics, maybe the disagreement is part of this? After all numerical simulations have to be violating lots of things and brought into line at the boundaries of the grids used.
In my mind, the importance of the Lidzen paper is not if it really is measuring the sensitivity to whatever feedbacks. It is if they have used the models in the same way as they have used the data when making the crucial scatter plots. If so, then the models are falsified, no matter if what is displayed is the true sensitivity or the true feedbacks.
Well I have serious concerns about the validity of the whole concept of the climate system as being any kind of “feedback” control system.
In this day and age, where feedback (electronic) systems are everywhere and controlling everything, the “froward gain block” (A) is almost universally, an “operational” amplifier. Control system freaks use them like popcorn.
At the lower frequency end of control things, the gain block (A) is a unidirectional transfer funtion. The design of op amps ensures that at the range of signal frequencies they are intended to process, the transmission (transfer function) from output to input is essentially zero; many orders of magnitude below the forward transfer function. The feedback network (B) is most often simple passive components, which can be either dissipative (resistors or conductors) and energy storage elements, most often capacitatice; but possibly and infrequently inductive.
As a result, one can usually say of the feedback network; that it is most certainly NOT unidirectional. A passive network can transmit signals in both directions simultaneously, and the backward, and forward transfer functions are usually easy to calculate; and may not be very different in magnitude. Signals applied at the input of the system (that (+) function can be transmitted directly through the feedback block (B) to the output; regardless of what goes on in the gain block (A); which is usually highly unidirectional.
Now many feedback systems at RF frequencies, such as feedback IF amplifier stages are quite bidirectional; often a simple resistor connected directly from input to output terminals, neither of which has a very high or a very low impedance.
So what does this have to do with the climate system.
Well the standard feedback mathematics employed in describing these climate feedback models; such as Dr Roy presnts here, tacitly assumes that the gain block (A) is also strictly unidirectional.
The output result at the output terminal can only influence the input via the feedback network (B); perish the thought that the climate function (A) could be bidirectional.
Now in fact a great many; if not most (or all) physical/chemical/biological functions that are seen in nature are highly bi-directional.
Le Chatalier’s Principle, Lenz’s law, Henry’s Law, and a host of other equilibrium criteria govern the “transfer funtion” of common systems that contribute in some way to weather and climate concerns. Warm oceans cause evaporation which changes the incoming ocean energy flux at either solar or LWIR wavelengths or both; and that in turn changes the ocean temperatures.
NO ! it isn’t feedback; it is simply a bidirectional reaction that can be driven in either direction. It’s the same thing as the rate equations in chemistry, where the reaction can proceed in either direction depending on the concentrations of the inputs and reaction products at both ends of the equation.
The simple feedback system diagrammed in Dr Roy’s essay; is hardly realistic as a representation of a climate process; it almost certainly is not valid to consider the gain block (A) which presumably contains the power source that drives the system to respond to the input signal; to be a unidirectional transfer function. It is highly likely to be as effective in the reverse direction.
This is why I simply cannot accept the popular notion that water is a “feedback” in the climate system; that responds to CO2 and other GHGs.
It is part of a complex bidirectional process that simply treats CO2 as something it encounters on the way to controlling the stability regime of the climate system.
And as usual this is simply the opinion of a Mathematical Physicist; who has been building stable feedback systems for longer than some climate data bases have been in existence; certainly a timescale comparable with the believable portions of the GISStemp database. And none of my points or opinions, are a result of proxies; they are all experimentally observed. The only ones that will be found documented would be found in the files of the United States Patent Office. ( a Peer reviewed process)
John S: “Devoid of independent power sources or amplifiers, it cannot physically implement any bona fide FEEDBACK within the system, i.e., become an ACTIVE system.”
Dunno about that … there is a multitude of passive systems which operate in feedback. Their responses to an input may be overdamped or underdamped. But, as you correctly to say, without a source of energy (other than the input), a PASSIVE system cannot amplify the input, nor can it be unstable.
Your main point is correct – we can draw a line between ACTIVE and PASSIVE systems on the grounds that a PASSIVE system has no more energy than provided by its input. The components of a PASSIVE system dissipate energy. To suggest instability in a passive system would breach the law of conservation of energy.
Slartibartfast: “Positive feedback” would mean an exponential increase in temperature”
I know where you’re coming from, but that’s not universally true. Positive feedback will produce a bounded output for a bounded input so long as the open loop gain is less than unity (at all frequencies).
But your point is correct for positve feedback where the open loop gain equals or exceeds unity (at any frequancy).
Only positive feedback has the capacity to amplify the input signal in closed loop. This is true even when the open loop gain is less than unity (that is, a large gain in the forward component ‘A’ more than compensated by the attenuation in the feedback component ‘B’). Given that PASSIVE systems cannot amplify their input, positive feedback can only exist in an ACTIVE system.
(I stick to the proper mathematical definition of positive and negative feedback: negative feedback is the arithmetic subtraction of the output signal from the input, and positive feedback is addition. The proper definition recognises that systems can go unstable in negative feedback – that’s just another good reasons to avoid the confusing definition adopted by climatology.)