Spencer on IPCC admission on climate feedbacks

In Their Own Words: The IPCC on Climate Feedbacks

by Roy W. Spencer, Ph. D.

feedback_system

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.

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96 thoughts on “Spencer on IPCC admission on climate feedbacks

  1. “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.”
    As always, well said.
    Chris
    Norfolk, VA, USA

  2. “… without any objections from the scientists who should know better.”
    Porque no? Because a global decrease in economic activity is seen as good (or at least prudent) in itself even if based on scientific malpractice?
    What? We have scientists who think they are economists too? “Convenient Lies” or “Convenient Silence”, both should be punished where applicable.

  3. Climate sensitivity cannot be measured directly but estimates can be made by observing climate change in the past or from short-term changes caused by volcanic eruptions. Knutti & Hegerl (2009) and IPCC (2007) conclude that various observations show a climate sensitivity value of about 3oC, with a likely range of about 2 – 4.5oC.
    See: http://www2.sunysuffolk.edu/mandias/global_warming/images/climate_sensitivity_lg.gif
    Furthermore, the lower value of climate sensitivity of 2oC is fairly well constrained which means that if emissions are not stabilized very soon, significant global warming is inevitable. According to Synthesis Report from the Climate Change Congress – University of Copenhagen (Richardson et al., 2009):
    “Recent observations show that societies and ecosystems are highly vulnerable to even modest levels of climate change, with poor nations and communities, ecosystem services and biodiversity particularly at risk. Temperature rises above 2oC will be difficult for contemporary societies to cope with, and are likely to cause major societal and environmental disruptions through the rest of the century and beyond.”
    Knutti, R. & Hegerl, G. (2008). The equilibrium sensitivity of the earth’s temperature to radiation changes. Nature Geoscience, (1), 735 – 743.
    Richardson, K., Steffen W., Schellnhuber, H., Alcamo, J. Barker, T., Kammen, D., et al. (2009, March). Synthesis report. Retrieved July 8, 2009, from Climate Change Congress – University of Copenhagen Website: http://climatecongress.ku.dk/pdf/synthesisreport/

  4. This is a very fundamental issue that lies at the basis of catastrophic projections/claims. Excellent to keep people focused on this most basic of as-yet “unsettled” aspects of the science.

  5. Bravo, Dr. Spencer.
    Now, can you dumb down the central part of this discussion so that, say, a second grader or a US Senator from either coast can understand the scientific argument? Then republish this or present it at the upcoming hearings on “AGW”, making sure to emphasize that great ending. “You’re preparing to spend how many trillions, perhaps even destroying the economy, on these guesses, Senator?”

  6. It is interesting that we can’t really measure the effect yet.
    Why would we be spending billions on the research yet not be able to measure the fundamental basis of the theory.
    I’ve always considered global warming to be a theoritical concept (that could still turn out to be accurate) but it is so complicated (trillions of photons interacting with trillions of molecules every nanosecond) that we have to prove/disprove/fine-tune it with factual evidence of what actually occurs.

  7. I saw the Crucible last night. I wish I could say that statement was O/T but unfortunatly the themes in the play hit a little too close to this topic than I would have liked. Particularly about jumping from victim to witch without any EVIDENCE.

  8. The atmosphere is a blanket. No blanket can trap heat the way the UN IPCC modellers predict, especially a gas blanket.
    And we hate politicians and economists faux scientist spretending to science is one translation.
    The science remains unsettled.
    Thanks Doc.

  9. Here is a radical approach:
    Fix the dishonest/unstable banking and money system that is causing all kinds of environmental damage and then quit worrying. It is called repentance.
    Or assume capitalism is flawed, apologize to Russia, and establish the USSA.

  10. This arcane debate is only important if one wishes to justify, or expell, the AGWERs’ temperature predictions for the next 100 years.
    Because, since temperatures have, at best, remained static for the last 11 years, whilst CO2 climbed, the theory demanding these future predictions is demonstrated wrong.
    I admire Pielke’s patience in playing the Lysenkoist game.

  11. Thanks Roy. Look forward to your presentation when available.
    Some amateur thoughts:

    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).

    Can these be distinguished by different phase, timing or trends between external and internal forcing?
    Richard Lindzen in Climate Change Deconstructed
    October 26, 2009, discusses positive feedback from global warming models (slide 46) vs negative feedback from ERBE and CERES on (slide 47).
    How definitive is this?
    Dr. Habibullo Abdussamatov in The Sun Defines the Climate – an essay from Russia shows a TSI graph

    Distinct short-term upward excursions are caused by the passage of faculae on the solar disk, and downward excursions by the passage of sunspot groups.

    The 0.1% short-term excursions in TSI and 0.1% long term solar cycle excursions provide external variations in forcing with differing frequencies.
    Satellites measure TSI, outgoing short wave (albedo) and long wave radiation as well as water in the atmosphere. Argo network measures sea temperatures. Cosmic rays are monitored.
    Ferenc Miskolczi predicts about constant global optical depth.
    I would be interested in comments on how useful these are in measuring the change in optical depth (water vapor + CO2), albedo and outgoing long wave radiation, vs the external forcing from the difference in TSI less reflections, and cosmic rays modulating clouds, relative to the uncertainties involved.
    Are the uncertainties in satellite measurements are still so high that it is difficult to measure the response to these variations?
    Nir J. Shaviv addresses The oceans as a calorimeter and solar amplification

    the TSI cannot explain the observed flux going into the ocean. An amplification mechanism, such as that of CRF modulation of the low altitude cloud cover is required.

    The temperature lapse rate vs altitude, height of the atmosphere, height of the troposphere, and water content of the atmosphere would seem to be other parameters that could be useful in evaluating the system.
    I would be interested in any comments on these vs the feedback parameters.
    How much do uncertainties need to be reduced to quantitatively evaluate the parameters? e.g. How much would it help to reduce uncertainties in measuring global water vapor to 0.1% or to 0.01%?

  12. What is extraordinary is that the IPCC projects 4 to 5 times the warming of the 20th century and the great majority of that is supposedly to come from positive feedback.

  13. Scott Mandia: “Furthermore, the lower value of climate sensitivity of 2oC is fairly well constrained which means that if emissions are not stabilized very soon, significant global warming is inevitable.”
    Circular reasoning at its best.
    Chris
    Norfolk, VA, USA

  14. 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
    Says who? This is an inverse problem. Complicated? Yes. Possibly the system, if it were linear, would be ill-conditioned; or perhaps it is non-linear, and in either case one would find an “ensemble” of systems, but wouldn’t that be more interesting than ensembles of these wearying and predictable simulations?

  15. RE: Scott A. Mandia (18:18:54);
    Your first paragraph seems to have been made in contradiction to what the article is saying. Did you read it? Or ignore it in favour of posting your rebuttal? The article is describing the issues relating to lack of certainty and estimates involved in climate modelling. Your first paragraph implies that climate forcings can be estimated – using the models that were described in the article as being based on estmates and not necesarily reliable… I am going in circles. Was there a point beyond agreeing with the article you were trying to make?
    Additionally, recent satelite data, included in Richard Lindzen’s latest paper, linked on this website and located here http://www.leif.org/EOS/2009GL039628-pip.pdf show that the estimated climate sensitivity, used in the models currently predicting high sensitivity are in fact suggesting low sensitivity and fall outside of the estimates given to models. All evidence I have seen in models suggesting high sensitivity are based on “best guess” (educated guesswork) and on the hope that as many climate variables as possible are included. Direct observations are showing the opposite to models, at the very least you must concede that there is an issue with the models (and not link back to models to prove the observable evidence incorrect..).
    As for the rest of the post you went on to discuss climate sensitivity on a small scale, such as a river network, or coral reef etc – comparably small in relation to a global scale. You cannot make an argument that says “the frogs in my local pond will go extinct if the temperate around the pond increases 2 degrees” and then raise that to “and therefore climate sensitivity on a global level is high” (which to be fair you did not explicity state that, but you did use local variability and estimates on climate sensitivity as an example following a speil about global climate which begs the inference).

  16. What I found to be a more striking admission on the part of the IPCC was in the Summary for Policymakers, which conceded that the question of whether anthropogenoic greenhouse gasses were responsible for most of the observed warming was purely a matter of opinion, rather than scientific procedure. They couched this admission in terms of “expert judgment” but that just begged the question of how those offering their opinon have demonstrated their expertise at attributing causation to an observed climate effect. If causation cannot be verified through measurments, then how can anyone claim actual expertise at attributing causation? It’s a cart-before-the-horse issue.

  17. Like David L. Hagen (19:20:09), I’m also curious about the relationship of Spencer’s remarks with Lindzen & Choi (2009)[1]. It seems that Spencer’s statement is in conflict with Lindzen & Choi, no?
    [1] Lindzen, R.S. and Y.-S. Choi, 2009: On the determination of climate feedbacks from ERBE data, accepted Geophys. Res. Ltrs.

  18. Lindzen and Choi (GRL to be published, I think) use ERBE and CERES radiation measurements in concert with sea surface temperature changes to infer a net feedback. This inferred feedback is overall net negative, giving rise to a net climate senitivity that is vastly smaller than the IPCC central tendency of 3 degrees for CO2 doubling and substantially smaller than even the 1 degree calculated for zero net feedback. Presumably by examining a large number of events, the noise due to random unforced changes is averaged out, and any net bias would tend to reduce the climate sensitivity even further.
    What’s wrong with this conclusion?

  19. Roger Sowell (18:49:41) :
    This gets into the feedback, which is the process control engineers’ domain.

    Interesting post. I’ll head off to read Dr. LaTour’s comments, but you mentioned that The steady-state gain (dt/dCO2) therefore is 0.0182 degrees C/yr, or almost zero.
    Shouldn’t the sensitivity value be in degrees C per quantity of CO2 rather than time? The temperature trend figure you quote is very small, almost zero in fact, but it is nonetheless the staff on which the AGWers hang their standards. The CO2 sensitivity is something we all wish we knew.

  20. If the climate really is a closed loop system, it is almost impossible to measure the feedback. You cannot determing 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.
    I suspect the ‘values’ for A and B vary with time and physical conditions, variations in orbit, small changes in TSI, etc. So we have a system better described by chaos theory than control theory.
    I’ve built a lot of closed loop systems. They had few inputs, few outputs, and not overly complex transfer functions. Still took a long time to wring out all the bugs. With climate, the variables far exceed the known equations, so finding the scale factors (and powers) is not much better than looking at tea leaves and animal entrails.
    Well done, Dr. Spencer. Someone has to address this issue. Perhaps a few people will listen to what you have to say.
    Jim F: Comparing a second grader to a U.S. Senator does a disservice to the kids in second grade. Most of them want to learn something.

  21. “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”
    But isn’t the IPCC case that the second statement is not true? As I understand their position, an increase in T causes evaporation to increase leading to higher atmospheric water vapor, which then end to increase T further due to its greenhouse gas properties. That is, an increase in T leads to a decrease in outgoing energy flux. This is my understanding of what they mean by “positive feeback”. Isn’t it enough to observe outgoing flux to be higher at higher T to refute this assumption? Not to say that you understand how, or can quantify a feedback parameter, but just whether feedback is positive or negative.
    It seems to me that the satellite data is enough to say the assumption is busted. Have I missed the point?

  22. Every now and then, one comes across someone who asks a question that pierces the fog of unreason. The importance of the issue raised by RS is self evident. My hat off in recognition of his clear thinking.

  23. If one takes an IPCC moel with positive feedback and runs it out a couple hudred years… do the seas boil?

  24. Dr A Burns (20:40:57) :
    Hmmm I read that and my first take was exactly the opposite of what the authors intended… I assumed signing a treaty at Copenhagen was the “dirty deal.” All a question of perspective.
    I wonder how much clout pathetic webtitions like this have to be honest, but a few to the contrary can’t hurt.

  25. Scott, I think you are putting the cart before the horse. There is no proof that this current warm spell is that much different from others, much less CO2 is the culprit.
    You say look at past climate change. OK, look at the temp rise in the early 1700’s (E. England, De Bilt, Uppsala, Berlin), that was not much different from the last 30-40 years.
    Or why the current global temps are have fattened out over the past 8-10 years, when the “models” predict they should be going up? If these basic questions cannot be answered, one runs the risk of doing more harm then good.

  26. 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.
    The nit picking comes if the sensitivity measured Lindzen’s way takes into account the objections raised by the present paper on whether what is purported to be sensitivity is the real sensitivity to a specific forcing, but is irrelevant to the scrapping of the models.

  27. Bulldust (21:16:18): If one takes an IPCC moel with positive feedback and runs it out a couple hudred years… do the seas boil?
    They most certainly do, according to Dr. James Hansen. The Venus Effect. The seas will boil away and all Life on this planet (and in the Universe as far as we know) will be kaput.
    http://wattsupwiththat.com/2008/12/21/jim-hansens-agu-presentation-hes-nailed-climate-forcing-for-2x-co2/
    All because you drive an SUV and use more electricity than a Pribilof Islander, you bounder.
    But then, looking at the last billion years or so, runaway global warming has not occurred, the proof being we are having this conversation. The End of Life hasn’t happened, yet.
    But I do expect boiling seas any day now. The consensus of dependent scientists (CODS) is that we passed the tipping point, in fact quite a few tipping points, years or months or weeks ago. So get out the tea bags and the sunscreen and try to make the best of it.

  28. Jim F (18:28:17) :
    Bravo, Dr. Spencer.
    Now, can you dumb down the central part of this discussion so that, say, a second grader or a US Senator from either coast can understand the scientific argument?

    Second grader? US Senator?
    ..
    What’s the difference?
    Well said….

  29. Retired Engineer (19:53:38) :

    If the climate really is a closed loop system, it is almost impossible to measure the feedback. You cannot determing 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.

    BINGO! Thank you for this sanity.

    I suspect the ‘values’ for A and B vary with time and physical conditions, variations in orbit, small changes in TSI, etc. So we have a system better described by chaos theory than control theory.

    I suspect there are way more gains than just A and delays than just B, but you state the same in one of your later sentences (which I have not included).

    I’ve built a lot of closed loop systems. They had few inputs, few outputs, and not overly complex transfer functions. Still took a long time to wring out all the bugs.

    Indeed. Multiple input, multiple output (MIMO) systems are difficult to analyze by themselves, feedback complicates this.
    Mark

  30. Mike D. (21:59:16) :

    But I do expect boiling seas any day now. The consensus of dependent scientists (CODS) is that we passed the tipping point, in fact quite a few tipping points, years or months or weeks ago.

    How do you refer to the individual scientists that make up the CODS? CODs pieces?
    Mark

  31. Kevin Kilty (19:52:21) :
    You are correct, and thank you for pointing that out. The steady-state gain dt/dCO2 should indeed by in units of degC / pct CO2. The fact that change in CO2 is very small over time also complicates the matter, which is one of Dr. Latour’s points.
    I also discuss this issue in my speeches to engineering groups, and stress that the inconsistency in response between temperature and CO2 (dt/dCO2) proves without any doubt that manipulating CO2 will not affect global temperature.
    As the available temperature and CO2 charts show, sometimes temperature falls, sometimes remains steady, and sometimes increases for decades, all the while CO2 increases. When a candidate manipulated variable (CO2) has those characteristics, it cannot be used to control the system.
    If only the world’s politicians understood process control fundamentals, all this nonsense of controlling global temperatures would cease.

  32. this is an astonishing quote from the ipcc report.
    in this context, there is another important issue revealed by mcintyre, where he demontrates how the ipcc report manipulated scientific results. a must read, and – implying rational thinking – suitable to convert agw believers to sceptics.
    http://www.climateaudit.org/?p=6590

  33. Yes, Watts up with that?
    Noblesse Oblige (19:41:44) :
    Lindzen and Choi (GRL to be published, I think) use ERBE and CERES radiation
    measurements in concert with sea surface temperature changes to infer a net feedback. This inferred feedback is overall net negative, giving rise to a net climate senitivity that is vastly smaller than the IPCC central tendency of 3 degrees for CO2 doubling and substantially smaller than even the 1 degree calculated for zero net feedback. Presumably by examining a large number of events, the noise due to random unforced changes is averaged out, and any net bias would tend to reduce the climate sensitivity even further.
    What’s wrong with this conclusion?

  34. Mark T 22.46.06
    Mike D 21.59.16
    Perhaps the clout exercised by the CODS could be referred to as CODSWALLOP.

  35. “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.”
    …Well, scientists have bills to pay too, you know. And let’s not forget if they dare speak the truth they’ll be ridiculed by their colleagues, and when they can’t publish their papers any more their research grants will dry up. I mean would you speak out under these circumstances or just keep quiet and save your job/reputation/lifestyle/mortgage/marriage?
    Come to think of it, the 20,000 politicians and global warming worshipers looking forward to their gangfest in Copenhagen are not going to take kindly to any scientist pointing out what a load of hogwash it all is. And so-called “Carbon Trading”? You might as well trade in pixidust and moonbeams for all the good it will do the environment.

  36. Dr. Spencer;
    Or anyone else here who can help me with a question that’s been nagging me for a couple days. The other day, in the comments for the first post about Monckton’s appearance on Glenn Beck’s show, I got into a tete a tete with another commenter about a study that utilized spectral analysis to separate the contributions of the various GHGs to the greenhouse effect. In googling about on the topic I came across another paper which covered the same ground from a slightly different perspective
    http://ams.confex.com/ams/Annual2006/techprogram/paper_100737.htm
    Evans and Puckrin 2006 Measurements of the Radiative Surface Forcing of Climate
    The link is to the abstract, you need to click the Extended Abstract link to access the pdf of the whole paper.
    The experiment in the paper utilized the spectral analysis technique to measure the downward LW radiative flux to the surface of the various GHGs. Since the paper is couched in the usual AGW blather, my first inclination was to doubt its qualities and indeed as a work of science I didn’t find much to recommend it. But, though their conclusions seemed fairly illogical, their experimental techniques seemed reasonable and the data in the their tables is what has had me ruminating. Particularly their Tables 3a and 3b which list respectively their seasonal observations for winter and summer. The readings for the cold dry air of winter show downward LW flux to the surface from CO2 at 30-35W/m2 and from H2O at 95-125W/m2 in line with the approx. 25% contribution of CO2 to the greenhouse effect. What’s shown in the summer readings is what has had me thinking. The H2O numbers went up to 178-256W/m2 in the warm humid air of summer, but the CO2 numbers went down, not just in relative terms but in absolute terms to 10.5W/m2, a third of the winter rate, and bringing the contribution of CO2 to the total GE to 3-4%, a much smaller value than I’ve usually seen quoted. this phenomenon was so obvious that even the clearly warmist authors commented on the higher H2O flux suppressing the flux from the other GHGs. Since this study was done in Canada and most heating of the planet occurs in the Tropic and Subtropic latitudes, which are presumably warmer and more humid than even the summer in Canada and would probably have even levels of H2O flux, if this phenomenon is real and consistent it would seem to me to indicate that contribution of CO2 at those latitudes would be an even smaller percent.
    I guess my first question is does any of what I’ve said make sense or am I completely misunderstanding this? If not, has anyone ever attempted these type of measurements in the tropics and if so were the results similar?

  37. typo;… have even higher levels of H2O flux,..
    …to indicate that the contribution of CO2 at those latitudes…

  38. fixed a typo I had:
    “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).”
    to Scott A. Mandia:
    The estimation of feedback from volcanic eruptions depends upon knowledge of the radiative forcing with time, and the heat capacity of the system, both of which have considerable uncertainty on the time scales involved. A wide range of values result depending upon those assumptions.

  39. Dave Wendt (03:36:31)
    I think I followed that. The observation which you highlight would be consistent with H2O and CO2 competing for the same or overlapping bandwidths so that with more H2O in the air as water vapour there is less bandwidth available for CO2 to absorb.
    With such a large effect as shown by those figures the ability of more CO2 to absorb and re-radiate when there is more H2O in the air seems to be grossly overstated.

  40. Dave Wendt
    Interesting link. H2O dominates, contributing 67% to 90% of the radiation, yet all the hoopla is over CO2. If H2O could be quantitatively measured would that not provide a critical measure of probably the most important parameter?
    This begs for the application of Ferenc Miskolczi’s quantitative comprehensive line by line HARTCODE radiation transfer program to evaluate the total optical depth. See Miskolczi’s 2008 PHYSICS OF THE PLANETARY GREENHOUSE EFFECT presentation slide 20 of variation in optical depth with latitude, which I infer to be equivalent to the variation in optical depth from summer to winter.
    The quantitative validation of LBL codes are discussed in: An inter-comparison of far-infrared line-by-line radiative transfer models David P. Kratz, Martin G. Mlynczak, Christopher J. Mertens, Helen Brindley,
    Larry L. Gordley, Javier Martin-Torres, Ferenc M. Miskolczi, David D. Turner, Journal of Quantitative Spectroscopy & Radiative Transfer 90 (2005) 323–341
    More importantly, the focus on radiative transfer of minor gases ignores the major effect of convective and latent heat transfer, and of the gross average optical depth. Miskolczi’s evaluations and models suggest that the global optical depth may be constant from energy minimization principles.
    Note the reduction in humidity over time. See: ‘Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data’ by Garth Paltridge, Albert Arking and Michael Pook
    journal of Theoretical and Applied Climatology

  41. michael (02:09:05)
    I’m relieved to hear you say that because my thoughts have led me to infer a zero effect from more GHGs on the basis that a change in the speed of the hydrological cycle produces an equal and opposite value to the initial forcing.
    As long, that is, as the initial forcing does not inject extra energy into the oceans which is why I am somwhat exercised by the significance or otherwise of the so called ocean skin effect as proposed by AGW supporters.
    I am pretty sure that the ocean skin effect has been given the wrong sign as suggested by me here:
    http://climaterealists.com/index.php?id=4245&linkbox=true&position=12
    If I’ve got it all wrong then the sooner someone demonstrates that the better even if I have to amend or even pull the article.

  42. some of the recent posts got me to thinking about our magical feedback force from h2o vapor. Claims I’ve seen are a rather fixed RH as temperature changes and it’s all about h2o vapor increasing with T. Going to the charts for absolute humidity I discovered that a 2 deg C rise with fixed RH achieves only a 1.1 x increase in the h2o vapor amount while a 5 deg C rise with fixed RH achieves a 1.3 x increase. In neither case does that translate into an increased forcing greater than that of the original co2 doubling according to a 1-d radiative model.
    The other generally acknowledged factor is that co2 doubling along contributes no more than 0.7 to 1.0 deg C rise and that the rest is all due to h2o vapor. It seems that the h2o vapor increase (in the basic statics case) combined with the co2 doubling is missing a full 3 deg C of additional warming with an assumed 5 deg C rise. It would seem also that the constant RH and absolute humidity constraints create a problem for the 2 deg C rise assumption as well in that the result is in the vacinity of 1 deg C for the combined effect of the increase in h2o vapor and the doubling of the CO2 and hence is missing almost a full deg C of forcing. Of course the second biggest assumption in this is going to be totally ignoring convection which, last time I looked, is going to reduce the effect further. The biggest assumption is the clear sky one which ignores clouds all together along with the water vapor cycle.
    Net result is that the RH constraint combined with the basic nature of water vapor means that it’s effect in the forcing is going to be much smaller than the CO2 even though the effect for an h2o doubling is equal to or greater than that of CO2. After all, the ipcc claims that 1W/m^2 of forcing is 1 W/m^2 regardless of the cause or specifics in how it affects.
    Do clouds on net increase or decrease T? Albedo is responsible for the averaged 107w/m^2 removal of power from the system. of the 0.3 Earth albedo, the dividing line between surface and atmosphere contribution is considered to be 0.22 for atmosphere (primarily clouds) and 0.08 for surface which is that low due mostly to oceans. If all the clouds suddenly dissappeared, the 239 W/m^2 radiative balance average would increase to over 313 w/m^2 and that corresponds to a stefan’s law increase of almost 10 deg C when the clear sky radiative efficiency of 70% is considered (only about 70% of the radiated surface emissions escape in clear skies). In my book, a 10 deg C increase needed to maintain balance with the removal of all clouds strongly indicates that the net effect of the present cloud cover has to be to reduce the temperature, regardless of which type makes up what % and how much CAGW types whine about it.

  43. Stephen,
    there is another tidbit. More trace ghgs in the atmosphere have an effect of increasing the emissivity of the atmosphere (in terms of stefan’s law concepts). That means one radiates more energy down at a given temperature for a chunk of gas and also that one radiates upward that same amount, requiring that the chunk of gas must become cooler as it is receiving an increase absorption that’s about half of the increase in emission – at least as one heads towards the boundaries. I don’t think this can actually result in a cooling but it certainly seems to indicate a lesser warming effect.
    Your referenced article was way too long for my reading time today so I only briefly skimmed it. That I didn’t see any glaring problems is a good thing but definitely nothing definitive. It did look reasonable.

  44. Regarding Spencer typo:
    I was confused by the first iteration and now also by the second. I was expecting that the same relationship between change in temp and radiative could be maintained by strong internal forcing with weak feedback (low sensitivity) or weak internal forcing with strong feedback (high sensitivity).
    Am wonderning now if I have failed to understand the terminology and relationships?

  45. Mark, having also been involved in the design of thermal process control systems, for many years, I agree with your comments on the time delay and MIMO. If you add to that non-linear effects in the forward and feedback loops, it takes a long time to work out the total system dynamics. In a sense there are loops within loops, within loops. All of which takes time to sort out. If I recall correctly we used Kalman filtering in a few cases, to help converge on models and solutions.

  46. Roger Sowell (23:25:11) :
    I agree entirely with you on the topic of controlling climate via CO2. By the way, I read the reply to the Letters in HP by LaTour, and not only was it a good read, but a first rate thumping, a polite thumping to be sure, for the fellow who wrote two ill considered letters in that issue. I was surprised, frankly, of the poor quality of thinking expressed in a couple other letters as well.

  47. David L. Hagen (06:43:54) :
    More importantly, the focus on radiative transfer of minor gases ignores the major effect of convective and latent heat transfer

    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.

  48. 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.

  49. 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?

  50. 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.

  51. 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.

  52. 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

  53. 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.

  54. 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.

  55. 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.

  56. 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.

  57. 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.

  58. 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?

  59. 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.

  60. “A proof is a proof is a proof.”
    My favourite ever quote, by Professor Minister Jean Chrétien.
    He never made more sense.

  61. 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?

  62. 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.

  63. 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.

  64. 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.

  65. 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.

  66. 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!

  67. 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.

  68. In classical feedback systems; the forward “gain block” (A) contains a power source that is the energy source that makes it all happen.

    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.

  69. 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.

  70. 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)

  71. 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.)

  72. “Only positive feedback has the capacity to amplify the input signal in closed loop.”
    Oops .. sorry, didn’t mean to say that bit! Negative feedback can amplify in closed loop, as many everyday examples of servos will happily demonstrate. (I think my mind was still on passive systems at that point).

  73. Anna V (10:21:44):
    Albedo at any level doesn’t change the total irradiance, only the fraction that is thermalized. Methinks John S. is deliberately keeping things simple in order to focus attention on the fact that an independent power source is required for any genuine feedback, to which the usual transfer functions apply. Otherwise, only recirculation is obtained. Many confuse the latter with the former.

  74. Jordan (16:02:25):
    Passive systems can recirculate (with or without dissipation) a fraction of the output, thereby stealing power from the output. Active systems sense the output, but don’t disturb it in any way. What is fed back in the latter is a replica of the output signal, which requires its own source of power. That makes for categorical differences in system behavior.

  75. Juraj V. (10:47:58) :
    Re Measurements of the Radiative Surface Forcing of Climate
    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.

    There’re not many H2O lines from 2000-600 cm^-1 (not microns!) and in the winter in Ontario on the day in question there wasn’t much H2O in the atmosphere. The band on the left is the ~15 micron CO2 band, 600-750 cm^-1.
    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

    That’s fig 3, the additional lines (the ‘grass’) cf fig 1 are the H2O lines.
    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).

    Tables 3a & 3b.

  76. sky
    “Passive systems can recirculate (with or without dissipation) a fraction of the output”
    Circulation without loss sounds a little too hypothetical. I’d suggest it’s best to assume dissipation for practical systems.
    I wonder if your reference to “circulating” energy is to energy storage. As I mentioned above, passive systems can be underdamped.
    A basic example would be a pendulum. Or a mass hanging at the end of a spring. Both of these systems will oscillate if they are given a single shove. The energy will “circulate” between kinetic and potential energy at different phases of each cycle.
    But we can all agree the initial input cannot be amplified without another source of energy. The oscillations cannot be greater than an amplitude defined by the limited energy provided by the initial shove. Without another shove, the oscillations will diminish over time due to losses.

  77. 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).

    AGH! Point taken. I’m so used to working with systems with loop gain > unity that I forget this.

  78. “AGH! Point taken. I’m so used to working with systems with loop gain > unity that I forget this.”
    Positive feedback tends to have very limited utility in engineering, and this little exception tends to be ignored and forgotten. I once got caught out on the same point in discussion ClimateAudit. AGH!

  79. sky: “Passive systems [steal] power from the output.”
    Power is an energy flow from a higher potential source to lower potential sink. The concept of a sink “stealing power” is novel, but probably of no practical use.
    “Active systems sense the output, but don’t disturb it in any way.”
    I disagree. Any “signal” involves a flow of energy. George E Smith will be able to tell you about the possible attenuation of electronic signals, and the importance of “impedance matching” at the input.
    “That makes for categorical differences in system behavior.”
    Again I disagee. If you accept the definition of passive and active systems I gave above, it will save you a lot of confusion.

  80. Again, in reply to sky
    “the fact that an independent power source is required for any genuine feedback, to which the usual transfer functions apply.”
    Afraid that’s complete nonsense. Feedback is in no way conditional on an independent power source.
    Imagine two tanks of water with a connecting pipe and valve. The level in one tank is below the other. When you open the valve. water flows into the lower tank, but the flow reduces as the levels in the two tanks equalise. That’s a passive feedback system to which “the usual transfer functions apply”. The only energy supplied to the system is in the initial conditions (and a trivial input to open the valve).
    “Many confuse the latter with the former.”
    Confusion probably goes back to the failure of climatology/earth sciences to adopt the standard concepts of feedback found in mathematical and engineering textbooks. The result appears to be no end of confusion over what different modes of feedback can do, stability conditions, and conservation of energy (which is the underpinning principle of systems analysis).

  81. Jordan (14:14:32):
    I fear that In your preoccupation with mechanical systems subject to the force of gravity and friction, you miss the entire point about the difference between feedback and recirculation (storage, if you wish) of system output in cases where there is no conversion of energy from kinetic to potential. Feedback in such cases requires a transducer at the output node and an external power source to replicate the output. That’s why the node is called a “pick-up point” in standard engineering terms. The output signal power is not affected by the transducer. In recirculation, the node is a branch-point, at which only a fraction of the available power goes out of the system. The complementary fraction is returned to the input for reuse. A common thermal example of recirculation is a boiler/radiator system. There’s a huge difference between the heat it produces and what would be obtained if the radiated heat were replicated and added to that from the boiler. That is more akin to the bogus feedback issue at hand than mechanical examples wherein the external (sic!) force of gravity acts as the power source.

  82. “”” Slartibartfast (10:22:57) :
    In classical feedback systems; the forward “gain block” (A) contains a power source that is the energy source that makes it all happen.
    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. “””
    Why do you assume that positive feedback means an “exponential” increase in temperature.
    In a sense, “positive feedback” means only that the feedback generates an additional signal at the input, which contains at least a component that has the effect of increasing the total input signal, and hence by inference, increases the output. But that is a far cry from asserting that the output must grow without limit; or at least until some non linearity or limit process stops the increase.
    The term “exponential increase” is bandied about a bit too freely.
    When water vapor captures LWIR emissions from the surface, thereby warming the atmosphere, and also warming the surface, as a result of the additional solar energy that arrives during that delay in the exodus of the LWIR; that is certainly a positive feedback effect. Water vapor can also have a negative feedback effect, in that it also can absorb insoming solar energy; thereby also warming the atmosphere; but in this case reducing the solar energy that reaches the ground; thereby resulting in a cooling. That is a negative feedback effect; even though the atmosphere was warmed (more) by the additional solar energy absorbed by the increased water vapor.
    But neither effect is a runaway condition; that leads to warming without limit; well until the “power supply rails are reached.
    However the phase change that occurs with water and not with other GHGs in earth atmosphere, kicks in a definite cooling of the surface (over climate time scales); and that is why the earth atmosphere condition cannot thermally runaway; like an out of control positive feedback loop with excessive gain.
    I’m surprised to see that some people feel that warmer surface temperatures should lead to less outgoing LWIR emissions, rather than much more as suggested by the usual blackbody radiation principles.
    Probably they are the same people who think that it is the polar regions that are cooling the earth.
    No the polar regions are cold because they don’t get enough energy from everywhere else to be at a higher temperature; it is not because they are more efficient radiators. It is the tropical deserts (and UHIs) that are the efficient radiators that are really cooling the planet; because of the Stefan-Boltzmann 4th power law. And when you consider that the CO2 absorption band is on the long wavelength side of the surface LWIR spectrum; then we should consider the peak spectral emittance at the LWIR spectrum peak; because that moves further away from the CO2 band as the emission temperature increases. And in that case the peak spectral emittance increases as the fifth power of the temperature.
    So hot things make effective energy radiators; cold ones do not.
    So I’m not surprised that that weird looking satellite sees more LWIR from warmer regions.

  83. sky (16:39:38) :
    My preoccupation is with conservation of energy.
    I have used examples of mechanical systems because it is easier to convey ideas using mechanical examples. It hope they will help others understand my misgivings about climate modelling. (More on that in a moment).
    The feedback systems I have given you are not considered “bogus” in the engineering world – a world where feedback concepts are routinely put to good use, allowing you to take them for granted.
    For example, my pendulum did not use gravity as its power source. The only energy source was the initial shove. Gavity only served as a mechanism to store energy in one part of the cycle. Same for the water tanks – the only energy input was the initial condition (the difference in the levels).
    As George E Smith correctly says, the climate model has had a number of control-systems misnomers applied to it, and climatologists insist on borrowing heavily from the systems engineering lexicon without paying much attention to what the various terms actually mean.
    I can assure you that anybody in climatology who wishes to carry out a formal mathematical analysis of feedback systems, the first thing they will do is to adopt the sensible convention of positive and negative feedback used by mathematicians and engineers.
    With that in mind, I suspect that nobody has ever had the need to invoke positive feedback to model a passive oscillator (such as a pendulum).
    You appear to be suggesting that the climate behaves as a passive oscillator. If so, an immediate consequence would be that the GCMs will then have been incorrectly formulated, if they use positive feedback mechanisms to explain the motion of the climate.
    You mention cases where there is no conversion of energy from kinetic to potential. The movement of energy is kinda central to systems analysis, so I struggle to think of an example of a real-world system which doesn’t involve a transfer of energy from one form to another.
    I never mentioned a transducer or “replication of output”. Methinks ’tis like a Red Herring.
    Maybe I do miss the entire point about the difference between feedback and recirculation (storage, if you wish). On recirculation, I think you are straying into Pascal’s objection (if memory serves me correctly). This states that you cannot return heat from the cold reservoir to the hot reservoir of a practical machine and expect a net gain in output. The amount of energy you need to put in to do so will always exceed the amount you get back. It’s another way of saying that we cannot have perpetual motion.
    So to leave you with a couple more examples.
    Let’s say you wish to be lifted to a height of 20 metres. Do you climb inside a bucket and lift yourself up 20 metres using the handle? No you cannot. So what makes you think you can send energy back to the input of a passive system to achieve an analogous result?
    Or, let’s say you’re watching your pendulum swiniging, and you guess that the air resistance is having an effect on the dynamics. So you put the pendulum into a vacuum chamber and set it swinging by giving it an initial shove. As you empty the chamber, what do you expect to see? Surely you don’t expect the absence of air in the chamber to result in the pendulum increasing the length of its swing! So what makes you think a change in the radiative transfer properties of the atmosphere can *amplify* a change in the temperature on the Earth? (To understand the question, be careful to understand what I mean by “amplify”.)
    These are just some more examples of the reasons why I am far convinced about the proposition of positive feedback in a passive climate system.

  84. John S. (09:50:15) :
    “The lack of grasp of the fundamentals of complex system behavior is what keeps “climate science” in its primitive state.”
    I applaud this statement. Complex (including chaotic and nonlinear) systems certainly do need to be understood better. The work by Tsonis such as “The Southern Oscillation as an Example of a Simple, Ordered Subsystem of a Complex Chaotic System” (1998) is a good start.
    I’m not an engineer of physicist. But I get the feeling people are using the term “feedback” in different ways and causing confusion. Feedback in the important sense in a chaotic system is what is also called damping or dissipation or friction, and it is the key ingredient for non-equilibrium pattern formation.
    Have a look at this video of spatio-temporal emergent patterns in vibrated corn-starch:
    http://chaos.ph.utexas.edu/research/vibrated_cornstarch.htm
    There are some cyclical phenomena visible: for instance the merging then separation of the persistent indentations from the blown holes. This event repeats in a cycle. At the end the protrusion of the fingers and the eventual collapse of each finger. This also has a timecourse.
    Engineers such as John S state that climate being passive cannot generate its own temporal dynamics – or only as some simple derivative of a forcing frequency. But the cornstarch shows emergent cyclical events with timecourses very decoupled and many orders of magnitude longer than the frequency of the forcing vibration.
    Tsonis treats the oceanic decadal oscillations as emergent spatio-temporal patterns in a chaotic-nonlinear system and this is the way forward for researching such systems, plus many other temporal and cyclical phenomena of atmosphere and ocean.

  85. I agree completely that positive feedback in a passive system is out of the question. Given the stringent requirement that no power be diverted from the output signal in any feedback sytem governed by a transfer function with the Laplace-transform representation H(s)/[1 – G(s)H(s)], I don’t think that even negative feedback can be physically implemented without recourse to some external source of power to replicate the output signal. Replication of output in the loop is at the very heart of all genuine feedback.
    Control system engineers are by no means shy in using a variety of configurations of sensors/transducers/servomechanisms/op-ams in the feedback loop to accomplish their goals (see, e.g., Fig 5.6 in Nise’s classic text.) Whether you recognize it or not, gravity is the external restoring force that powers the pendulum response. Without it, the pendulum would not swing in response to any forcing.
    Finally, my reference to bogus feedback was not directed at your mechanical examples, but to the ungrounded notions prevalent in climate science. To see a system block-diagram with an op-amp in the foward loop–the simplest control system configuration–in a discussion of natural climate is highly perplexing, to say the very least. Op-amps are always independently powered. No one has come up with any credible explanation of what the corresponding natural mechanism would be. Let’s leave it at that.

  86. Jordan (06:22:35):
    I completely agree that positive feedback in a passive system is out of the question on energy conservation principles alone. Inasmuch as any feedback system governed by the transfer function H(s)/[1 – H(s)G(s)] relies upon replication of the undisturbed output signal in the feedback loop, I don’t think that even negative feedback is possible without an outside power source. Control system engineers are not shy at all in using independently powered sensors/transducers along with servomechanisms and op amps in the feedback loop to achieve their goals (see, e.g., Fig 5.6 in Nise’s classic text).
    Gravity does supply external power in your mechanical example. Without it, the pendulum would not oscillate in response to applied nonoscillatory forcing. Please note, however, that my reference to bogus feedback was not aimed at your mechanical examples, but at the prevalent misuse of the term in climate science. Let’s leave it at that.

  87. Thank’s for your constructive reply sky. Still a couple of point at issue.
    Gravity only stores energy in the pendulum. It is the initial shove that gives it some kinetic energy, which then oscillates between kinetic at the lowest point in the swing, to potential energy at each extreme.
    No shove, no movement, no oscillation.
    “Inasmuch as any feedback system governed by the transfer function H(s)/[1 – H(s)G(s)] … I don’t think that even negative feedback is possible without an outside power source.”
    I’ll give you an example of a simple series RC filter with input voltage V1(t) and output voltage V2(t).
    The Laplace Transform current through the resistor: R.I(s) = V1(s) – V2(s)
    The Laplace Transform of current at the capacitor I(s)= C.s.V2(s)
    (on the initial condition, output voltage V2(t=0) = 0)
    The negative feedback here is the reducing current (reducing potential across the resistor) as the capacitor charges or discharges to the try to achieve equilibrium at V2 = V1.
    We can equate the two equations for I(s):
    RC.s.V2(s) = V1(s) – V2(s)
    which simplifes to a neat linear transfer function:
    V2(s)/v1(s) = 1/(1+RC.s)
    This has the form of the transfer function you mention. The change of sign from – to + in the denominator is becuase of the negative feedback.
    It short, negative feedback exists without a power source in a passive system. The only source of energy to a passive system is the energy provided by the input. As the components of passive system dissipate energy (unconditionally in practical systems), a passive system will always produce a bounded output for a bounded input, consistent with conservation of energy.

  88. Jordan (09:34:50):
    My first comment yesterday (17:28:56) dissappeared from the thread, prompting me to resubmit an abridged version (18:24:38). It now mysteriously reappears! Sorry for the repetition.
    I’m even more sorry, however, to see your persistent confusion about the role of internal and external variables in a system. Gravity is not a capacitance effect that “only stores energy in the pendulum.” It is a persistent external force that provides all the restorative power. If you look up the governing nonlinear differential equation in normal form, you’ll find it on the same side as the forcing function, but with opposite sign, in a classic example of negative feedback. Without it, the position of the pendulum would continue to change indefinitely in response to any forcing.
    Your notion thata passive RC filter constitutes feedback, because the voltage across the resistor can be expressed in similar algebraic form as a feedback system transfer function, convinces me that fundamental features of system analysis continue to escape you, along with many others. It is the relationship between system output and input signals that the transfer function specifies, not some state of internal components. Passive RC filters have no effect whatsoever upon the input signal. Without such an effect–the sine qua non of feedback control–it makes no sense to speak of system “feedback.” I will not elaborate this any further.

  89. sky
    You may recall from high school physics how the potential energy of a body of mass ‘m’, at a height ‘h’ (from some datum) can be expressed as:
    Q = m.g.h.
    When I used this in our discussion on the above thread, I suppose it was a way of testing whether your knowlege of dynamics has progressed as far as high school physics. But you do insist on coming back here with more confused arguments.
    It is not MY notion that a passive RC filter constitutes feedback. I was taught that as an undergraduate when I was studied for a batchelors degree in …. wait for it … control engineering!
    When you mentioned the transfer function, I thought it might be worthwhile to spell out the negative feedback in that passive RC circuit. To make it easy for you I even said specifically how the changing output voltage will be in the direction which reduces further changing voltage. But you still come back to argue about it. I would not expect such an argument from a first year undergraduate engineer.
    If you cannot take it from me, why not get yourself an undergraduate text book in control engineering. I thought my comments would help, but you seem intent on making an argument whatever I say.
    My only request would be to spare the community on this site any more of your confused notions of feedback theory. Because I would feel the need to reply to misinformation.

  90. Jordan:
    The issue is not what you were “taught,” but what feedback systems actually do. They operate–by definition– not just on the input signal, as with the RC filter, but upon the output signal, as well. That’s why the complete transfer fuction has both H(s) for the forward system function and G(s) for that in the feedback loop. There simply is no feeback of the filtered signal in the classic RC configuration. Unlike with feedback, the input signal left unaltered.
    As for elementary physics, take pendulum out to space an give it a shove. You’ll find that in the absence of any other external force, it will not oscillate, but simply revolve around the pivot point indefinitely.
    Wanting to enjoy my weekend, I’ll leave you with a final thought: condescension is never a good substitute for clarity of analysis.

  91. sky
    I wanted to show you how the net response of the RC circuit is the combination of the input and the output. The transfer function I gave encapsulates those internal interactions.
    It should be enough to convince you that negative feedback exists in passive systems. We don’t need to discuss it further here.
    Take a pendulum out to space and we have turned one of the parameters down to zero. After a shove, we expect to get circular motion (rather than an arc) as the limit of reducing the gravity parameter to zero. The physical system hasn’t changed and the mathematical model shouldn’t need to be changed.
    We could call gravity an external force if it was useful to do so. But it is analogous to calling the electrical field across a capacitor an external force. What would be the point? It seems more parsimonious to get straight to the point – these can be represented as energy storage devices.
    I’m sorry if I was condeseding. But undergraduate engineers would have points deducted for suggesting there is no feedback in a simple RC circuit. With that in mind, it doesn’t do WUWT any good to have such ideas being aired here.

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