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“Misdiagnosis of Surface Temperature Feedback”

Filed under: — mike @ 29 July 2011

Guest commentary by Kevin Trenberth and John Fasullo

The hype surrounding a new paper by Roy Spencer and Danny Braswell is impressive (see for instance Fox News); unfortunately the paper itself is not. News releases and blogs on climate denier web sites have publicized the claim from the paper’s news release that “Climate models get energy balance wrong, make too hot forecasts of global warming”. The paper has been published in a journal called Remote sensing which is a fine journal for geographers, but it does not deal with atmospheric and climate science, and it is evident that this paper did not get an adequate peer review. It should not have been published.

The paper’s title “On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth’s Radiant Energy Balance” is provocative and should have raised red flags with the editors. The basic material in the paper has very basic shortcomings because no statistical significance of results, error bars or uncertainties are given either in the figures or discussed in the text. Moreover the description of methods of what was done is not sufficient to be able to replicate results. As a first step, some quick checks have been made to see whether results can be replicated and we find some points of contention.

The basic observational result seems to be similar to what we can produce but use of slightly different datasets, such as the EBAF CERES dataset, changes the results to be somewhat less in magnitude. And some parts of the results do appear to be significant. So are they replicated in climate models? Spencer and Braswell say no, but this is where attempts to replicate their results require clarification. In contrast, some model results do appear to fall well within the range of uncertainties of the observations. How can that be? For one, the observations cover a 10 year period. The models cover a hundred year period for the 20th century. The latter were detrended by Spencer but for the 20th century that should not be necessary. One could and perhaps should treat the 100 years as 10 sets of 10 years and see whether the observations match any of the ten year periods, but instead what appears to have been done is to use only the one hundred year set by itself. We have done exactly this and the result is in the Figure..
[ed. note: italics below replace the deleted sentence above, to make it clearer what is meant here.]

SB11 appears to have used the full 100 year record to evaluate the models, but this provides no indication of the robustness of their derived relationships. Here instead, we have considered each decade of the 20th century individually and quantified the inter-decadal variability to derive the Figure below. What this figure shows is the results for the observations, as in Spencer and Braswell, using the EBAF dataset (in black). Then we show results from 2 different models, one which does not replicate ENSO well (top) and one which does (second panel). Here we give the average result (red curve) for all 10 decades, plus the range of results that reflects the variations from one decade to the next. The MPI-Echam5 model replicates the observations very well. When all model results from CMIP3 are included, the bottom panel results, showing the red curve not too dis-similar from Spencer and Braswell, but with a huge range, due both to the spread among models, and also the spread due to decadal variability.



Figure: Lagged regression analysis for the Top-of-the-atmosphere Net Radiation against surface temperature. The CERES data is in black (as in SB11), and the individual models in each panel are in red. The dashed lines are the span of the regressions for specific 10 year periods in the model (so that the variance is comparable to the 10 years of the CERES data). The three panels show results for a) a model with poor ENSO variability, b) a model with reasonable ENSO variability, and c) all models.

Consequently, our results suggest that there are good models and some not so good, but rather than stratifying them by climate sensitivity, one should, in this case, stratify them by ability to simulate ENSO. In the Figure, the model that replicates the observations better has high sensitivity while the other has low sensitivity. The net result is that the models agree within reasonable bounds with the observations.

To help interpret the results, Spencer uses a simple model. But the simple model used by Spencer is too simple (Einstein says that things should be made as simple as possible but not simpler): well this has gone way beyond being too simple (see for instance this post by Barry Bickmore). The model has no realistic ocean, no El Niño, and no hydrological cycle, and it was tuned to give the result it gave. Most of what goes on in the real world of significance that causes the relationship in the paper is ENSO. We have already rebutted Lindzen’s work on exactly this point. The clouds respond to ENSO, not the other way round [see: Trenberth, K. E., J. T. Fasullo, C. O'Dell, and T. Wong, 2010: Relationships between tropical sea surface temperatures and top-of-atmosphere radiation. Geophys. Res. Lett., 37, L03702, doi:10.1029/2009GL042314.] During ENSO there is a major uptake of heat by the ocean during the La Niña phase and the heat is moved around and stored in the ocean in the tropical western Pacific, setting the stage for the next El Niño, as which point it is redistributed across the tropical Pacific. The ocean cools as the atmosphere responds with characteristic El Niño weather patterns forced from the region that influence weather patterns world wide. Ocean dynamics play a major role in moving heat around, and atmosphere-ocean interaction is a key to the ENSO cycle. None of those processes are included in the Spencer model.

Even so, the Spencer interpretation has no merit. The interannual global temperature variations were not radiatively forced, as claimed for the 2000s, and therefore cannot be used to say anything about climate sensitivity. Clouds are not a forcing of the climate system (except for the small portion related to human related aerosol effects, which have a small effect on clouds). Clouds mainly occur because of weather systems (e.g., warm air rises and produces convection, and so on); they do not cause the weather systems. Clouds may provide feedbacks on the weather systems. Spencer has made this error of confounding forcing and feedback before and it leads to a misinterpretation of his results.

The bottom line is that there is NO merit whatsoever in this paper. It turns out that Spencer and Braswell have an almost perfect title for their paper: “the misdiagnosis of surface temperature feedbacks from variations in the Earth’s Radiant Energy Balance” (leaving out the “On”).


282 Responses to ““Misdiagnosis of Surface Temperature Feedback””

  1. 101
    Paul S says:

    Carrick (re: the post that is mistakenly in the other thread) – ‘What climate sensitivity you end up with seems to have more to do with the assumed aerosol forcings’

    Could you elaborate on what you mean here because it doesn’t make sense to me. Climate sensitivity is defined as the magnitude of temperature response to an amount of radiative forcing. Aerosols change the amount of net forcing, not the climate sensitivity.

  2. 102
    Brian Dodge says:

    simon abingdon says: 31 Jul 2011 at 1:22 PM “#81 Jim Eager ‘those molecules can act as either a feedback or as a forcing’.
    How can you tell which are which?”

    Well, if those dastardly profiteers at Exxon/Mobil and Peabody coal hadn’t cleverly disguised Fossil Fuel Emissions as ordinary CO2, and had instead labeled them properly, we would be able to tell them apart!
    Oh, wait, my bad – they did! Thanks, fossil fuel industry.

    ReCAPTCHA say – lyintike out

  3. 103
    RW says:

    Gavin,

    “You need me to more specific? I really don’t want to have to spell it out for you since working it out for yourself is likely to be the only way you will make any progress (if indeed you make any). Work out what the connection is between your ‘bound on sensitivity’ and the actual sensitivity in a simple model.”

    Is it too much to ask for some specific questions from you? I’m more than willing to answer them (or at least try).

    From your link, I see the equations for the GHE, where ‘G’ (ground flux) equals half of what’s absorbed by the atmosphere plus ‘S’ (the incident post albedo solar power of 240 W/m^2. I don’t have an issue with this, as it properly depicts that half of what is absorbed by the atmosphere goes to space and half is returned to the surface. You’re using an atmospheric absorption of 0.769, or perhaps more importantly a ‘window’ transmittance of 23.1% or about 90 W/m^2 (390 x 0.231 = 90). Are you backing your way into these numbers from an assumption of a 288K surface temperature, which emits about 390 W/m^2 from the surface, or are you getting them from some other means? I don’t really have an issue with these numbers, as I think they are at least roughly accurate. I’m just curious.

    [Response: The 0.769 comes from trying to match the surface temperature. - gavin]

    In the ‘Radiative Forcing’ section, the equations to get Ftop/(1-0.5*lambda) where you’re using ‘S’, which is the post albedo solar flux of 240 W/m^2 to get ‘G’, the ground flux of 390 W/m^2, is the surface response to solar forcing ‘S’ that I’ve been talking about. The result of the equations is the same as multiplying the 3.7 W/m^2 by the inverse of net transmittance to space of 0.615 (240/390 = .615) as I mentioned before. 1/0.615 = 1.63; 1.63 x 3.7 = 6 W/m^2. 3.7/(1-0.5*0.778) = 6 W/m^2.

    An additional 6 W/m^2 is about equal to a 1.1 C rise in temperature. 396 = 289.1K from S-B.

    You then go on to define ‘feedback’ as that which is acts only the +3.7 W/m^2 while ignoring the feedbacks acting to maintain 390 W/m^2 flux at the surface from the 240 W/m^2 flux from the Sun.

    [Response: No. Your claim is that sensitivity can be defined from the ratio of S to G. Specifically, that the ratio 1 \over { (1-0.5\lambda_0)} provides some sort of bound. However, using the simplest form of the feedback shows that the sensitivity is 1 \over { (1-0.5(\lambda_0+\lambda^\prime))} which can be larger or smaller than your number depending on what the feedbacks are doing. The more basic issue is that you are linearising the GH effect from 0 to the present value - and that is simply not sensible. More generally, I can show you any number of simple models to complex models all of which have the same S and G but which do not have the same sensitivity. Doesn't that make clear that the former does not constrain the latter? - gavin]

    Let me pose the question to you in a different way. If the radiative ‘forcing’ from 2xCO2 is 3.7 W/m^2 and the current atmosphere only provides 2.3 W/m^2, where is the additional 10.6 W/m^2 incoming surface flux required for a 3 C rise (16.6 – 6 = 10.6) coming from? If you think it’s the ‘feedback’, from where specifically? If from a reduced albedo, how? If from increased atmospheric absorption, again how? And why doesn’t the ‘feedback’ cause anywhere near proportionally this much change on the 240 W/m^2 flux from the Sun?

  4. 104

    From basic physics, water evaporates and clouds form (or not) in response to water temperature and vapor pressure, which are results of amount and distribution of energy in the system. So clouds are a dependent variable, not an independent variable, ie not a forcing, and no lagging statistics can do anything about that. As far as I’m concerned, that alone totally disproves the entire hypothesis Spencer has contrived of “internal radiative forcing,” including but not limited to this most recent paper of his with Braswell, and I find it difficult to focus on this paper long enough to fully appreciate the statistical manipulations.

    But it does raise a general question about the computer modeling of climate, or possibly about advanced statistics, I’m not really sure what exactly I’m getting wrong here. From page 1610 of Remote Sensing, page 8 of the pdf of Spencer / Braswell 2011, third paragraph:

    For the radiative forcing N(t) we used a time series of normally-distributed monthly random numbers with box filter smoothing of 9 months to approximate the time scales of variations seen in the climate models and observations in Figure 3. A separate time series of random numbers without low pass filtering was used for the non-radiative forcing S(t). This mimics what we believe to be intraseasonal oscillations in the heat flux between the ocean and atmosphere seen in the data [5,13]. The model time step was one month, and the model simulations were carried out for 500 years of simulated time.

    I don’t understand the validity of using random numbers to model all forcing, and from their equation (1) and discussion of it on page 2, it’s clear that S(t) & N(t) are all the forcing terms they consider in their simple model. And both S(t) & N(t) are random. So they seem to be modelling only randomly fluctuating forcing.

    CO2 concentration obviously fluctuates, but seasonally, not randomly, and it increases over time, as anybody can see from the full Mauna Loa record, or any several consecutive years even. So, what’s with the “random” forcing? That seems to me just too obviously invalid. It seems to be blatantly setting up the consensus theory as a straw man “hypothesis” that can’t help but fail! But their methodology can’t possibly be quite that bad, can it? What am I missing? Is that really natural variability which they’re modelling with random numbers, and I’m just thrown by their misuse of the word “forcing” or what?

  5. 105
    Eric Swanson says:

    #89, Hank Roberts asked:

    How much of ‘the climate system’ do the satellites cover, how much is extrapolated?

    The CERES instrument data Spencer used was from the TERRA satellite, which is in a sun synchronous orbit. The time of equator crossing is 10:30 AM local time in the descending direction, moving NNE to SSW mol, and the orbital period is 98 minutes. The fact that the vehicle is sun synchronous means that the cross track scanning measurements take a quick snapshot of the radiances at a fixed time of day for each point in latitude. There are 14.7 orbits a day, thus for each latitude in the 60N to 60S range, only 2/14.7 of a day, once on the sun side and once on the dark side, or 3.3 hours of coverage is available. The raw measurements must be run thru a mathematical process, which involves scene identification as well as a model of the specular albedo which uses the angle of the scan to convert to emissions. I’ve not deeply studied the process, but my WAG is that there are several potential sources of error in this processing. Kevin should be able to provide a better answer regarding the accuracy of the CERES data…

  6. 106
    One Anonymous Bloke says:

    Paul S #98, Jim Eager #100: thank you.

  7. 107
    simon abingdon says:

    #86 #95 One Anonymous Bloke

    I’m glad my questions caused sufficient feedback to help clear up your confusion.

  8. 108
    simon abingdon says:

    gavin, Ray Ladbury, Jim Eager et al

    Thank you for helping to disabuse me of prejudice.

    simon abingdon

  9. 109
    Edward Greisch says:

    73 Marie: “If logic and solid science is marketed well”

    If only we had a marketing budget……

    We don’t. RealClimate is it for NASA-GISS. And neither does the IPCC. The IPCC cannot do any job of PR at all because the IPCC is under the control of member governments.

    There is nothing irresponsible going on on our side. It is just that RC is run by poor but poverty stricken scientists, not a rich corporation. NASA is a government agency. That means NASA is under the control of congress which is under the control of…..

    Now, if you happen to have a billion dollars to spare, I’m sure it could be put to good use.

    Climate Science is not a money making corporation. The fossil fuel industry is a lot of money making corporations.

    [Response: RC is nothing to do with NASA, or NASA-GISS. If you want to see their public outreach efforts go to http://www.giss.nasa.gov or http://climate.nasa.gov etc. - gavin]

  10. 110
    One Anonymous Bloke says:

    Simon Abingdon, it’s easy to get confused by these issues. “Forcing” and “feedback” are best described in Mathematical terms, English can only provide metaphors. I am pleased to hear your confusion (or prejudice if you prefer) has also diminished. If you and I can be better informed, perhaps there is even hope for Roy Spencer.

  11. 111
    Tea Partier says:

    “…From basic physics, water evaporates and clouds form (or not) in response to water temperature and vapor pressure,…”

    (#103)

    Obviously not everyone thinks it’s that simple, starting with Svensmark and the cosmic ray/cloud forcing theorists. Svensmark’s paper on Pacific cloud response to forbush events indicates there are situations where clouds could be a forcing element. Whether this triggers ENSO events in turn, I don’t know, but then neither does anyone else, as the science of ENSO cause has not yet progressed to the point where we can actually predict it in advance (apologies to the late Theodor Landscheidt).

    [Response: Even in this situation the clouds are acting in response to a forcing (as they would be doing with any indirect aerosol effect). The point above is that clouds do not spontaneously decide to have decadal variability - the time scales for their creation/dissipation are just too short (hours to days, vs. years). - gavin]

  12. 112
    Paul S says:

    #101, my response to Carrick – After some thought I believe I understand what you’re getting at: If two models have been tuned specifically to match 20th Century observations then any difference in climate sensitivity between them could partly be explained by differing forcing inputs.

  13. 113
    Pete Dunkelberg says:

    Gavin @ 111, do you mean the climate system didn’t just decide in 1880 to drive itself uphill?

  14. 114

    A question–Gavin (inline response to #111) wrote that “. . .clouds do not spontaneously decide to have decadal variability – the time scales for their creation/dissipation are just too short (hours to days, vs. years).”

    True as far as it goes, I’m sure–but couldn’t some precondition for cloud formation persist over much longer timescales than the clouds themselves?

    Reasoning by analogy is dangerous, I know, but tornado outbreaks last longer than the individual tornadoes do, and (on a vastly longer timescale) the Quaternary has outlasted its individual glaciations and interstadials. Might there not, in principle at least, be some analog to these examples that affects cloud formation rates?

    (Of course, it’s essentially empty speculation unless there’s some physical mechanism that one might at least guess at. Presumably the cosmic ray thing doesn’t really cut it, since IIRC there’s no evidence of a trend there, or at least not one that matches temps.)

    [Response: Of course. No-one doubts that there may be significant changes in clouds over decadal and longer timescales, but you put your finger right on the issue - there has to be a precondition that has a longer memory. This might be the oceans (changes in SST patterns altering convection, jet streams etc., changes in atmospheric composition (via ozone depletion, or aerosols, or GHGs) etc. In such circumstances the clouds are acting as a feedback to the original change, not a forcing in and of themselves. Cosmic rays would be a forcing that caused forced changes in clouds, but that wouldn't constrain the climate sensitivity (and as you say, has little or nothing to do with recent trends - although that is a different issue). - gavin]

  15. 115
    Meow says:

    @113: Well, you see, around 1880 there was an invasion of Maxwell’s Demons, and….

  16. 116
    simon abingdon says:

    #114 “the clouds are acting as a feedback to the original change, not a forcing in and of themselves”. The original change, eh? Surely you glimpse the flinty path of the infinite regress here gavin?

    [Response: Not in the slightest. We are not discussing the "First Mover" problem, but rather the impact of a boundary condition change on a system. If the solar irradiance increases, it doesn't matter in the slightest for this conversation whether it happened because of chaotic dynamics in the photosphere or the massing of a legion of solar fire dragons pointing their breath in our direction. - gavin]

  17. 117
    Tea Partier says:

    “….Response: Even in this situation the clouds are acting in response to a forcing (as they would be doing with any indirect aerosol effect)…”

    (Gavin)

    True enough, but I thought this Spencer paper (SB11) was about divulging climate sensitivity to temperature change. At the risk of over-simplification, Dessler 2010 (D10) seems to say: changes in ocean currents cause SST changes, which in turn cause radiative flux changes (including those from cloud cover change); thus the sensitivity of the climate system can be divulged by regressing radiative flux against SST.

    SB11 is saying you cannot divulge climate sensitivity to temperature change by this method since cloud cover change drives radiative flux changes which in turn drives SST change, which in turn drives radiative flux changes etc. It doesn’t matter whether cloud cover change is driven by smoke from forest fires, or cosmic rays, or natural oscillations as Spencer claims, the pertinent fact is that cloud cover change precedes SST change.

    [Response: No-one is disputing that cloud changes affect radiation or that ocean temperature changes can affect clouds (or at least I hope not). The net radiation changes Spencer is correlating is not just clouds though, it is the whole system. For the period in question (10 years), I doubt very much whether total climate sensitivity can be constrained - and as far as I can tell Dessler does not claim this. Indeed, nor does SB11, which is odd given the press they got (which claims that they indeed have). What can be constrained is the behaviour of aspects of this problem - i.e. some of the fast feedbacks. ENSO variability is a coupled mode that does it's own thing without regard to cloudiness (since it is driven by Kelvin waves in the ocean etc.), so looking at the cloud response to the ENSO-related SST variables gives a clue as to the cloud feedback to surface warming. It is only a clue though because the pattern of ENSO SST changes is not a perfect analog to the SST changes related to 2xCO2. In that situation, we have that global surface temperatures are lagged by a few months to the ENSO index, and Spencer's calculation shows a maximum regression to energy loss a few months after a temperature max. This makes sense and is seen in the models above as well. Similarly, we see (in both models and obs) that things that cause an energy gain cause a temperature rise after a few months. Again, unsurprising. If you are claiming that this pattern doesn't constrain sensitivity, then I am in violent agreement. What Kevin's pictures above show is that this pattern is clearest when you have strong ENSO variability (since that dominates coordinated/coherent interannual variability). - gavin]

  18. 118
    Hank Roberts says:

    > original change … flinty path

    Simon’s assumption is that human fossil fuel use can’t be the original cause for the rapid change in climate. Anything but ….

  19. 119
    Joe Hunkins says:

    From a social science perspective it’s interesting how predictable the highly critical posts are here at realclimate. Peer reviewed papers by authorities who challenge the prevailing view are disparaged as worthless and unscientific, where even the most pathetically uninformed alarmist comments are welcome and only rarely challenged. It remains incredible to me how few here are willing to characterize the transparent and obvious bias as anything but objective and analytical truth. More importantly, it would sure be nice to see a lot more testable assertions about both the accuracy of climate models and climate modelling.

    [Response: Oh please. I spend almost all my time trying to find testable assertions about climate change responses in models to compare to observable data. It is surprisingly non-trivial to find useful comparisons that actually constrain something important - something we have discussed here frequently. Yet the contrarian media can go nuts with a misinterpretation of some new study that doesn't constrain what they think it does, and when we point that out, you accuse us of being un-objective. That's pretty funny. You might want to consider the thesis that the papers challenging the orthodox view are indeed mostly worthless and unscientific. That is not to say that are not worthless and unscientific papers that support the orthodox view, but they don't generally make it to Drudge and we don't get a ton a phone calls asking us what we think. - gavin]

  20. 120
    R. Gates says:

    Chris @ #79:,

    Thanks for that, and it does make sense to a point, but it seems that the distinction between positive feedbacks and a “forcing” gets to be a bit blurry, and perhaps this is partially related to the nature of a system like the climate existing on the edge of chaos. Here’s what I mean: Milankovitch cycles are the initial forcing agent that seems to control the onset of glacial periods and interglacials. In these situations, CO2 becomes a positive feedback response that amplifies this slight nudge from the additional NH insolation. Milankovitch could be viewed at the “trigger” forcing agent, but then, CO2 outgassing from the oceans becomes a secondary forcing agent via it’s positive feedback. And here’s to me, the unique aspects of these secondary forcings agents. They must be internal to the system and along with their amplifying positive feedback mechanism, they must also create some ultimate negative feedback that can shut down the positive feedback so that we don’t get a “run-away” situation. In essence, a secondary internal forcing must act as a governor or thermostat.

    [Response: The factor that prevents run-away conditions is always the same - the basic Planck response, none of the amplifying feedbacks come close to challenging this despite their importance for assessing net climate sensitivity. (Note that constraints on sensitivity on paleo-timescales are not related directly to sensitivity to Milankovitch since the seasonality/latitude dependence of this forcing combined with the hemispherical asymmetries means that the global radiative forcing/response concept does not work). The factors that translate Milankovitch forcing to climate change (the ice sheet and carbon cycle response mainly) are external to the principle model system (as described above) and so can be thought of as external boundary condition changes for which the radiative forcing concept works well. - gavin]

  21. 121
    Marie says:

    #109: “The IPCC cannot do any job of PR at all because the IPCC is under the control of member governments.”

    I beg to differ. IPCC is mandated to aggregate the science. All member states sign off on the collation and therefore all member states agree with whatever eventually comes out of this process (there are fights over the more politically-sensitive numbers, I’ll bet). Which means they can very well better-market the science. It IS irresponsible. Science is of no use if you scrabble away at your craft and don’t bother learning to communicate it to the world. You have receptive media, you have receptive journalists, you have the potential to collaborate on PR. By the way, good PR is not necessarily costly. I have seen great PR campaigns run on very little. On the proactive side, it’s about good targeting, good collaborations, good use of all possible media, good and consistent messaging; and on the reactive side, it’s about not just milling around discussions like these, and actually getting these messages out to the public via the media! Not having enough money is just an excuse for not trying. You can have a billion dollars and a crap PR agency and still not get your message across. I was not talking about RC specifically. IPCC draws on the work of thousands of scientists from thousands of institutions which all have marketing and PR personnel; IPCC itself has or has had communications people. There are thousands of PR firms who do pro-bono work, and thousands of bright communications graduates looking for an internship, for a shot, and to contribute to something bigger.

    It IS irresponsible not to communicate your work to the world well, when so much hinges on it. Look at the simplicity of how this piece of work was communicated in the first place. The right article to the right media at the right time.

    Pull your head out of the sand. Work with your communications departments, or educate them better. I am still reeling from the pathetic defeatist attitude and the lack-of-money argument. This should be your time, and yet you roll over without a fight and bleat about a lack of funds, when you have so much truth and responsibility and the persistence of the scientific method on your side. (The bloodthirsty hunger to rip apart each other’s work alone should convince the world that whatever survived the process is pretty damn kosher.)

  22. 122
    Jack Roesler says:

    Spencer claims they measure much more infrared heat escaping the atmosphere than climate models predicted. Could the incoming sunlight that reflects off the aerosol clouds, a condition that is artificially cooling the climate system, be interpreted by the satellite’s instruments as infrared? I doubt it, but thought I’d ask.
    Secondly, why did he wait 10 years to announce that finding? I would think it would have been detected in a matter of days. Too bad we don’t have a new satellite up there to make these measurements. It seems every time we launch one to measure some aspect of global warming, it either blows up on the pad, or fails to achieve orbit. Isn’t that interesting?

  23. 123
    Joe Hunkins says:

    …. papers challenging the orthodox view are indeed mostly worthless and unscientific.

    Gavin I certainly respect the fact that you must spend/waste a lot of time addressing nonsense, such as the mischaracterization of this Spencer paper in Forbes and the tendency of skeptics to ignore obvious truths. But I’m not talking about that – I am noting the challenges of accepting what seems to be a premise here at RC along the lines that “… papers challenging the orthodox view are mostly worthless and unscientific.” Such a predisposition is a pretty slippery slope even for a fine scientist like you and the others posting here.

    [Response: It is a predisposition that has a pretty strong Bayesian prior at this point. Is everything written by Spencer automatically flawed? Not at all. However, are the blatant 'dog whistle' press releases and lame counter arguments ('people that disagree with me don't believe in the conservation of energy') completely transparent? Yes. It would be great if people were to bring their best arguments forward instead of continually bringing their worst, and for me, it would certainly be more interesting. But these periodic blogospheric explosions almost inevitably are based on misreadings and misrepresentations of the most obvious kind. If we ignore them, we are accused of either a lack of communication nous or of elitist arrogance, and if we deal with them, we get accused of only focusing on the easy-to-rebut nonsense. I don't see any way to win those p***ing contests so I don't try. If people aren't interested in what I or others here have to say, they don't need to read. If you have constructive suggestions for might be more interesting to discuss, I'm all ears. - gavin]

  24. 124
    One Anonymous Bloke says:

    Joe Hunkins, #119: You are mistaken. There is nothing “disparaging” about pointing out the error in someone’s calculations. You are also mistaken about climate models having no testable predictions, see BPL’s list, for example. That is not to say that individuals don’t have their own particular confirmation biases, along with 100% of the rest of the human race. As one of the ‘pathetically uninformed’, I find people here are more than willing to address my errors, despite having no obligation to do so – especially in light of the numerous articles herein.
    Appeals to the social sciences will not avail you: try Physics and Chemistry.

  25. 125
    RW says:

    Gavin,

    “No. Your claim is that sensitivity can be defined from the ratio of S to G. Specifically, that the ratio 1 \over { (1-0.5\lambda_0)} provides some sort of bound. However, using the simplest form of the feedback shows that the sensitivity is 1 \over { (1-0.5(\lambda_0+\lambda^\prime))} which can be larger or smaller than your number depending on what the feedbacks are doing. The more basic issue is that you are linearising the GH effect from 0 to the present value – and that is simply not sensible. More generally, I can show you any number of simple models to complex models all of which have the same S and G but which do not have the same sensitivity. Doesn’t that make clear that the former does not constrain the latter?

    I’m not claiming that sensitivity can be precisely ‘defined’ by the ratio of G to S. I’m saying in such a highly dynamic, yet very stable system as the climate clearly is, it establishes a boundary – or an upper limit on sensitivity because the net feedback on the whole must be negative in order to keep the system as tightly constrained as it obviously is.

    I do think some more longer term positive ‘feedbacks’ of a few percent are possible, but not 300% or more of the initial response of atmosphere. The system would be massively unstable if this were the case.

    [Response: I'll let Gavin respond to the rest, but let me jump in right here and point out that this statement is wrong. The net feedback need not be negative. The net feedback can be (and is) positive. Note that a net positive feedback can be result in a tightly contained system too: how much so depend on how the feedback strength goes with the mean state. To understand this better, I highly recommend Roe, G.H., 2009: Feedbacks, timescales, and seeing red. Annual Reviews of Earth Plan. Sci., 37, 93-115, or if you don't want to get into it that much, read Chris Colose's post on feedbacks at RealClimate (here). --eric]

    Besides, most of the enhanced warming supposedly comes from combined water vapor and cloud feedbacks, which operate on the order of hours to days or weeks – not over years or decades.

    Also, I’m not linearising the GHE from 0 to the present. There is a difference between the absolute response and the incremental response, but it is very small – something on the order of 1% and is infinitesimal. The atmosphere is already absorbing about 300 W/m^2 of the 390 W/m^2 emitted from the surface. An increase in absorption of 3.7 W/m^2 from 2xCO2 is 1.2%. 1.1 C x 0.012 = 1.11 C, or about 1/100th of a degree C. Ant crumbs.

    You do know that the post albedo S is not a constant, right? It varies all the time with varying cloud coverage and via aphelion/perihelion procession. The cloud portion of the albedo is big part of the control mechanism maintaining the net surface flux of 390 W/m^2. If the climate as a sensitive as you believe, we would be see a much greater increase in temperature when the post albedo S is at it’s maximum amount. Maximum S actually occurs in September closer to aphelion rather than at perihelion in January due to maximum surface reflectivity coinciding with the Northern Hemisphere winter in January.

    At the very least, can you tell me where specifically the watts are coming from to cause the 3 C rise? I presume you know that if the surface is to warm by 3 C, it must also emit 406.6 W/m^2 (+16.6 W/m^2) and Conservation of Energy dictates that the +16.6 W/m^2 flux into the surface has to be coming from somewhere, right?

  26. 126
    ccpo says:

    @71 simon abingdon says:
    31 Jul 2011 at 2:16 AM

    Why should some CO2 be regarded as a forcing while the rest is regarded as a feedback?

    Simpler than Gavin, because you can’t seem to understand simple science:

    Because we put it there, not the climate system.

    I do not believe you misunderstand this, so I ask, why ask such a ridiculous question?

  27. 127
    ccpo says:

    I am noting the challenges of accepting what seems to be a premise here at RC along the lines that “… papers challenging the orthodox view are mostly worthless and unscientific.” Such a predisposition is a pretty slippery slope even for a fine scientist like you and the others posting here.

    Again, let me simplify where Gavin has expounded: You are confusing “predisposition” with “fact.” Gavin gave you a far more learned response, but I think for the non-scientists, it is best to KISS it.

    To be specific: We need to note your premise is faulty. A large number of papers are treated as garbage, so RC scientists are biased.

    You ignore the premise: A large number of papers are treated as garbage because they are garbage, so RC scientists are not biased.

    The only biases we have divined are your biases: When climate scientists discuss flaws in papers that cause those papers to fail to overturn the current understanding of climate, you don’t like it.

  28. 128
    Chris Colose says:

    RW (125)

    Actually, I don’t agree with Dr. Steig that the net feedback is positive, at least when you include the increased IR emission with temperature. If you include this feedback, the net feedback must be negative to retain a stable system. The problem is in definitions. As Roe explains in his paper (that Dr. Steig referenced), this increased IR emission with T is just the “reference system” (as I mentioned in my post, you get about 0.3 C warming per unit radiative forcing under this system); climatologists like to define positive or negative feedbacks relative to that reference system. Operating under this framework, this allows you to say that feedbacks are more positive than negative without losing physical consistency.

    Mathematically, the response dT is dT = dT_o/(1-f), where the traditional “feedbacks” are encompassed in the definiton of f, but dT_o IS the Planck response (i.e., the reference system).

    Here is another mathematical exercise to constrain the climate sensitivity without additional (non-Planck) feedbacks.

    We know the traditional energy balance equation is S(1-a)=4εσ Ts^4

    where S is the solar constant, a albedo , σ the S-B constant, ε the bulk planetary emissivity, and Ts the surface temperature.

    We can differentiate this equation assuming only a perturbation of CO2 (i.e., the ε term, which decreases). The derivative of the left hand side is zero.

    We have,

    0 = (4σTs^4)dε + 4ε(4σTs^3)dTs

    This yields for the change in surface temperature,

    dTs = (-Ts/4)(dε/ε)

    Note that dε is negative, so dTs will be positive. We know that εσTs^4 is 240 W/m2, and from radiative forcing calculations dε(σTs^4)= – 4 W/m2 (for a doubling of CO2); thus the ratio dε/ε is -4/240.

    Thus,

    dT = (288/4)(4/240)= 1.2 C

    which is the no-feedback sensitivity widely cited. Amplifying this by three is not problematic at all, which you can easily do by putting more water vapor in the air, in addition to some other feedbacks.

    I would also note that the perturbed *surface* energy budget is not just governed by increased upwelling/downwelling IR radiation, but also by adjustment to evaporation and sensible heating fluxes.

    [Response: Chris: yes, of course, the Planck feedback is a negative feedback, but the argument is about the magnitude of the other feedbacks (clouds, water vapor, etc.). My point is simply that in your equations, 'f', which encompasses those, is a positive number, but that doesn't make things "unstable" (as RW seems to think) unless f > 1.--eric]

  29. 129
    Ray Ladbury says:

    Joe Hunkins,
    ‘Kay, buddy. Time for you to cite your top ten contrarian papers in climate science. Let’s find out just what revolutionary breakthroughs mainstream climate science is missing. But as you cite them, don’t you find it odd that almost to a paper, they aren’t published in top-tier climate journals, and how few citations they tend to receive, and how the authors often publish another paper the following year that contradicts the previous year’s? Do you really think that’s how science works?

    Anyway, I look forward to being wowed by your list.

  30. 130
    RW says:

    Eric,

    “I’ll let Gavin respond to the rest, but let me jump in right here and point out that this statement is wrong. The net feedback need not be negative. The net feedback can be (and is) positive. Note that a net positive feedback can be result in a tightly contained system too: how much so depend on how the feedback strength goes with the mean state. To understand this better, I highly recommend Roe, G.H., 2009: Feedbacks, timescales, and seeing red. Annual Reviews of Earth Plan. Sci., 37, 93-115, or if you don’t want to get into it that much, read Chris Colose’s post on feedbacks at RealClimate (a href = “http://www.realclimate.org/index.php/archives/2010/09/introduction-to-feedbacks/”>here)

    You need to do better than this. The net feedback operating on the Earth’s energy balance or net surface flux of 390 W/m^2 in the current climate has to be negative (and probably really strongly negative). The globally averaged temperature anomaly barely fluctuates by more than a few tenths of a degree per year despite a large amount of local, regional and seasonal hemispheric variability. Even when the globally average mean fluctuates by a large amount like during an El Nino, it always seems to revert to its pre-equilibrium state quickly. Hardly consistent with net positive feedback – let alone net positive feedback of 300% or more. Besides, if very small changes or perturbations resulted in dramatic changes (i.e. net positive feedback), the climate would be fluctuating from year to year over a much larger range and would be a very inhospitable place for life and the biosphere as a whole. Life could not have evolved under such conditions. If the net feedback was that strongly positive, what would prevent the system from going out of control from just a few day or weeks of abnormally warm weather? Yet curiously this never happens.

    With regard to the glacial to interglacial sensitivity, you can’t equate the positive feedback effect of melting ice from that of leaving maximum ice to that of minimum ice where the climate is now. There just isn’t much ice left, and what is left would be very hard to melt, as most of is located at high latitudes around the poles which are mostly dark 6 months out the year with way below freezing temperatures. A lot of the ice is thousands of feet above sea level too where the air is significantly colder. Unless you wait a few 10s of millions of years for plate tectonics to move Antarctica and Greenland to lower latitudes (if they are even moving in that direction), no significant amount of ice is going to melt from a measly 1 C rise in temperature. Furthermore, the high sensitivity from glacial to interglacial is largely driven by the change in the orbit relative to the Sun, which changes the angle of the incident solar energy dramatically. This combined with positive feedback effect of melting surface ice is enough to overcome the net negative feedback and cause the 5-6 C rise. But we are very nearing the end of this interglacial period, so if anything the orbit has already flipped back in the direction of glaciation and cooling.

    [Response: You're confusing 'positive feedback' with 'runaway feedback'. They are not the same thing. I agree with you that the positive feedback cannot be too positive, or the climate sensitivity would be much larger than it is. We may be talking past each other a bit here though -- see Chris's comment above and my response. --eric]

  31. 131
    RW says:

    Eric,

    “You’re confusing ‘positive feedback’ with ‘runaway feedback’. They are not the same thing.

    I’m aware of the difference. Positive feedback of 300% needed for a 3 C is not ‘runaway feedback’. Perhaps “going out of control” was not the best word usage, as it does imply some type of runaway effect. That wasn’t what I meant though.

  32. 132
    RW says:

    Chris Colose (RE: 128),

    Before I respond, have you read all of my posts in this thread from the beginning?

  33. 133
    Pete Dunkelberg says:

    RW, I don’t really understand what you are thinking, but you may be overlooking the matter of convergent series, the easiest one to show being one half + one fourth + one eight + … = 1.

  34. 134
    Hank Roberts says:

    > Positive feedback of 300% needed for a 3 C

    No, you’re assuming the number you’re being asked to think about.

  35. 135
    Hank Roberts says:

    Here’s a link to the paper Eric recommended (inline response) above:

    Roe, G.H., 2009: Feedbacks, timescales, and seeing red. Annual Reviews of Earth Plan. Sci., 37: 93-115.

    http://earthweb.ess.washington.edu/roe/Publications/Roe_FeedbacksRev_08.pdf

  36. 136
    Dave123 says:

    RW-

    I’ve looked through your posts here and on skeptical science.(at least I think it’s you)… you confuse rhetoric with science and math.

    “With regard to the glacial to interglacial sensitivity, you can’t equate the positive feedback effect of melting ice from that of leaving maximum ice to that of minimum ice where the climate is now. There just isn’t much ice left, and what is left would be very hard to melt, as most of is located at high latitudes around the poles which are mostly dark 6 months out the year with way below freezing temperatures. A lot of the ice is thousands of feet above sea level too where the air is significantly colder. Unless you wait a few 10s of millions of years for plate tectonics to move Antarctica and Greenland to lower latitudes (if they are even moving in that direction), no significant amount of ice is going to melt from a measly 1 C rise in temperature. Furthermore, the high sensitivity from glacial to interglacial is largely driven by the change in the orbit relative to the Sun, which changes the angle of the incident solar energy dramatically. This combined with positive feedback effect of melting surface ice is enough to overcome the net negative feedback and cause the 5-6 C rise. But we are very nearing the end of this interglacial period, so if anything the orbit has already flipped back in the direction of glaciation and cooling. ”

    This is all rhetoric and assertion of opinion. Words like {“measly” aren’t admissible without calculations to back them up. I’m not even sure you understand the difference between heat and temperature after all this time, otherwise you wouldn’t write stuff like “1 C isn’t enough to do X”. Temperature is NOT a surrogate for heat as you are using it. If I hold an arbitrarily large mass of ice in presence of air that is always 1 C warmer (or .00001 C warmer) than 0 C (in an otherwise closed system), the ice, all of it, will eventually melt, because I’m supplying an effectively infinite heat source to the ice. So please at least stop saying really wrong things like that. (And your earlier remarks about the increased thermal emission sound like you’re still having 2nd law mis-understandings).

    I’ve built chemical reactor models…simple by comparison to a global climate model, but the underlying principles, physics and chemistry based are the same. When people like Gavin or Chris talk, I know they’re speaking the language and understanding the science and I can trust them to be close to right. You don’t have the ring of either truth or comprehension in anything you write.

    And the thing is this: My models and simulations worked. They were implemented on a large scale and produced thermal profiles, yieids and capacities within measurement error of what the simulation scenarios came up with. (Like climate models, it’s a matter of what conditions I chose…what we chose to operate the plant at, if I said “run it like this and the simulation predicts X under that scenario, then X we would get. Unlike climate models, the plant operators listen to me.)

    In my view, you’re wasting people’s time. You’ve used up more than your fair share. Look, I don’t understand international tax law. I’m seeing accountants about it tomorrow. I’m going to put my trust in them. You clearly don’t, after much ado understand the scientific and mathematical basis of this stuff… at some point you just need to hang it up and trust Gavin and Chris and the rest. And you don’t put your trust in Spencer, again because having read “11″, the critiques published are dead on- it’s a scientific travesty, a breach of norms. It creates false comparisons (which models get compared to).

  37. 137
    Hank Roberts says:

    PS for RW — did you spend some time reading Roe, before you dismissed the paper? It seems your definitions don’t match the definitions in the publications cited. Do you mean to refer to “feedback factor” above?

    For example Roe cautions about terms:
    “In the electrical-engineering literature and the control-systems literature, both c1 and c1λ0 are referred to as the feedback factor …”
    — and Roe notes the importance of being clear what definition is used.

    For another example Roe says
    “… in Equation 8, the two feedback factors are f1 = 1/3 and f2 = 1/2. Thus from Equation 11, the combined feedbacks produce a total system gain of G = 1/(1 – 1/3 – 1/2), or 600% of the original response—more than twice what one might expect….”

    Could that be where you’re having trouble matching the numbers published?

  38. 138
    Edward Greisch says:

    109 gavin: Thanks for the outreach URLs. Who hosts RC?

    121 Marie: “Work with your communications departments, or educate them better.”

    WHAT communications departments? Where I worked, communication was forbidden. I worked for the military and everything was secret.

    “IPCC is mandated to aggregate the science.” And that is all. They are not mandated to advertise.

    “which all have marketing and PR personnel” Wrong. None of them have marketing personnel. Climate scientists work for the federal government or for universities. Outreach is a new thing that happens in some agencies. That means the web sites http://www.giss.nasa.gov and http://climate.nasa.gov

    “The right article to the right media at the right time.” WRONG. You forgot a few things about the media: They don’t speak our language [math]. They are beholden to advertisers or owned by the enemy. The public doesn’t know any science. They charge money for advertising. There is no right media.

    Read “Merchants of Doubt” by Oreskes and Conway and “Climate Cover-Up” by James Hoggan. See: http://climateprogress.org/2010/10/14/video-proof-david-koch-the-polluting-billionaire-pulls-the-strings-of-the-tea-party-extremists

    Sorry, but scientists are not marketers. There is a personality difference.

    If you would like to take over the communications job, it is yours. Show us how to do it. Otherwise, I suggest you try being a physicist for a while.

  39. 139
    Chris Colose says:

    RW,

    I’ve glossed over the exchange, with the exception of the RC post Gavin linked you too. I think Gavin has so far responded quite clearly to you.

    There is enough evidence now to show that the mean climatological fluxes do not constrain climate sensitivity, and must be assessed from examining changes in climate (see Schmidt et al., 2010, JGR). Your attempts at linearization over the mean climate make no sense.

  40. 140
    IA says:

    RW said:
    “Before I respond, have you read all of my posts in this thread from the beginning?”

    Chris and Eric, you should by now be aware that RW is not really interested in your answer and will continue to obfuscate for as long as you play with him. He tried the same at Stoat and other blogs. My guess is that he fully understands what you are saying but keeps raising the same errors to hijack the discussion.

    He was asked (on another blog) to set up his own blog, present the maths and the model that he believes is operating (along with some hints on the physical basis of his model) and see what comments he gets. Has he done this?

  41. 141
    Charles says:

    Joe Hunkins,

    I’m with Ray: what “contrarian” papers do you think are really noteworthy insofar as providing solid alternate theoretical models to explain observations and/or providing solid data to back up these theoretical models? In one sense, I’d love the whole “AGW model” to be wrong, but I just don’t see any consistent and comprehensive alternate theoretical models with good data to support them. And each time a paper like Dr. Spencer’s comes out, folks in certain media outlets and elsewhere are quick to trumpet that this one study has “blown the lid off” the mainstream consensus.

    Of course, there is plenty we still don’t know, but thus far it seems to me that the mainstream consensus model is by far the best, the most consistent, and the most comprehensive explanation of what is going on and what is likely coming in the future.

  42. 142

    #114 (inline response)–

    Gavin, thanks for the clarification/expansion.

  43. 143

    #130–

    “You need to do better than this.”

    RW, do you have any clue what a condescending jerk this makes you sound like? Particularly when you then go on to make a whole paragraph of unsupported hand-waving?

    Dr. Steig has credibility; you don’t, much, and you’re rapidly losing any that might be granted by way of courtesy. So when you dictate to him, in his forum, how or what he ‘needs’ to do, you’re making a loud (and not very flattering to you) statement about how you view yourself and how you view others. Dr. Steig and the other contributors here don’t, after all, ‘need’ to spend time writing for our edification.

    I doubt that you want to make this kind of impression, but perhaps you don’t realize how you are coming across. My advice, FWIW: if you’ve got points to make, make them calmly and succinctly, and lose the attitude.

  44. 144
    Hank Roberts says:

    Spencer’s paper. That would be good to return to, eh?
    Focus or lose the thread to hobbyhorse stuff which has been seen before.

  45. 145
    Ray Ladbury says:

    RW,
    You claim the feedback in climate is “strongly negative”. ‘Kay, so why does it warm rapidly when the sun comes up? Why does it start to warm right after the equinox? How has it been warming steadily for 35 years? And finally, why isn’t Earth a big snowball since its blackbody temperature ought to be ~255K on average?

    It seems to me that if you would simply stop waving your hands and actually do the math, you’d realize exactly how much trouble you’d be in with a model with “strong negative” feedback. It wouldn’t look much like Earth.

    [Response: Let's keep it civil folks. The point Chris Colose emphasized -- that of course the most important feedback, the fact that as the temperature goes up, the radiation to space goes up too, is negative -- is indeed a stabilizing force and could be considered 'strong'. All this qualitative discussion isn't very helpful evidently, but I'm not convinced RW was trying to be difficult here. In any case, as Hank Roberts says, how about let's get back on topic.

    By the way, for those interested in PDFs of climate sensitivity and the like, Roe has a new paper out this week providing some interesting new points (though their main conclusion is that arguing about the details of the PDFs is largely pointless! Paper is here]

  46. 146
    simon abingdon says:

    #126 ccpo “I ask, why ask such a ridiculous question?” Given your assumption, the same query could be applied equally well to your own question, ccpo.

  47. 147
    simon abingdon says:

    #118 Hank Roberts “[my] assumption is that human fossil fuel use can’t be the original cause for the rapid change in climate”. Hank, we’re at cross-purposes here as to the meaning of “original”. I suggest that “the evolutionary trick of fire-control” or “the mammalian niche” are rather more “original” explanations. However, gavin’s (#116) amusing hypothesis of “the massing of a legion of solar fire dragons pointing their breath in our direction” is originality of an altogether different dimension.

  48. 148
    Radge Havers says:

    Joe, from a social science perspective, I have to say that I find this very odd:

    “It remains incredible to me how few here are willing to characterize the transparent and obvious bias as anything but objective and analytical truth.”

    Is that a testable assertion?

    “More importantly, it would sure be nice to see a lot more testable assertions about both the accuracy of climate models and climate modelling.”

    How hard have you looked? What are you assuming here?

    “I am noting the challenges of accepting what seems to be a premise here at RC along the lines that “… papers challenging the orthodox view are mostly worthless and unscientific.” “

    “Seems.” This would all be less impressionistic if you were backing it up. Did you have some specific problem with the critique? I’m only asking, because otherwise your take on this pretty much echos empty, over generalized, party-line rhetoric.

  49. 149
    Rick Brown says:

    The new paper by Roe and Armour that Gavin refers to inline at #145 is available here: http://earthweb.ess.washington.edu/roe/GerardWeb/Publications_files/grl_submit.pdf

  50. 150
    Pete Dunkelberg says:

    RC: “the pdf is here. Not exactly but happily it is here.

    And it says

    “So, as noted in RB07, while the probabilities become more focussed,
    in other words the range { however measured } gets less, the cumulative likelihood beyond 4.5 oC remains stubbornly persistent.”

    In other words we cannot bound the risk by any acceptable value. Weitzman must be taken seriously.

    But then the paper continues

    “Secondly, and more fundamentally| T2 is only a
    metric of a hypothetical global mean temperature rise that might occur thousands of years into the future.”

    I thought the discussion was about short term sensitivity (and long term sensitivity may be larger). What am I missing?


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