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Spencer's Misdiagnosis of Surface Temperature Feedback

Posted on 3 August 2011 by Kevin Trenberth

This is a re-post of an article by Kevin Trenberth and John Fasullo on RealClimate

The hype surrounding a new paper by Roy Spencer and Danny Braswell (SB11) is impressive (see for instance Fox News); unfortunately, the paper itself is not. News releases and blogs on climate "skeptic" 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 the methods in the paper is not sufficient to be able to replicate the 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. 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 Figure 1. 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 1: 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 Figure 1, 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”).

This post has also been developed into the Advanced rebuttal to Roy Spencer finds negative feedback.  We also put together a Basic version.

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Comments 1 to 19:

  1. ScienceDaily has treated Spencer & Braswell paper as just another peer-reviewd, published paper. This is extremely unfortunate because many people believe SienceDaily to be a credible sources of information about the lastest scientific discoveries. Kudos to Kevn Trenberth and John Fasullo for setting the record straith and for allowing SkS to re-post their most informative critique of the Spencer & Braswell paper.
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  2. Badger, I know, not encouraging. ScienceDaily has a huge readership. I am perplexed that they would uncritically promote this shoddy paper, and state its (false) findings as fact. Have you contacted SD to let them know? Me thinks that like "Yahoo news", they have been hoodwinked.
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  3. Well, the Yahoo article was just a re-post of a Heartland article originally in Forbes. Re-posting anything climate-related from Forbes is a horrid idea, but Science Daily's article is their own. They didn't interview any other scientists, or metion that Spencer is a notorious "skeptic". They should know better.
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  4. As a non-scientist I've been labouring under the delusion that the practice of good science was to compare theory and speculation against measured observations. I can see that Spencer is producing models which incorporate measured data but like so many papers trying to debunk AGW how does this work attempt to explain melting polar ice caps, retreating glaciers, coral bleaching, ocean acidification and so on. I'd have thought that the myriad of warming symptoms warrant explanation rather than dismissal. Can any of you folks point out where I'm going wrong with this line of thought please?
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  5. Stevo - Spencer would argue that the observed warming has mainly been caused by some natural effect causing cloud cover changes (he fails to identify what this effect might be). This 'natural' warming effect could cause melting ice caps and glaciers. Warming oceans and acidification cause bleaching, etc. However, there are a number of man-made warming 'fingerprints' which Spencer's and other "skeptic" alternative hypotheses generally can't explain. They tend to gloss over that fact.
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  6. Thanks Dana. I now feel safe to conclude that Spencer equals bad science.
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  7. I had a sceptic friend send the S&B paper to me last Friday. I gave him a brief rundown of Spencer's (abysmal) record on climate modelling, but was delighted to send him this rebuttal when I saw it on RealClimate. It still won't convince him, though...
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  8. Is there any prediction from Spencer that could be added to the Lessons from Predictions series?
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  9. Given the dearth of posts praising the Spencer and Braswell paper, the climate Denial Spin Machine must be having a hard time coiming up with talking points to defend this latest piece of Swiss cheese from Dr. Spenser. PS -- Who the heck is Braswell?
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  10. Alexandre - I've never seen a prediction from Spencer (or Christy) that we could put to the test. If you can find one, I'd be more than happy to do a post on it. "Skeptics" tend not to put their money where their mouths are. They like to criticize others without making predictions themselves. We had to reconstruct a 'prediction' from Lindzen based on his previous comments (see Lindzen vs. Hansen) because even though he's researched the climate for 40 years, he's never made a concrete prediction either. Badger - Braswell is a colleague of Spencer at UAH.
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  11. This certainly deserves a "Wow!" or even three. Taking Responsibility on Publishing the Controversial Paper “On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth’s Radiant Energy Balance” by Spencer and Braswell the paper by Spencer and Braswell that was recently published in Remote Sensing is most likely problematic in both aspects and should therefore not have been published. After having become aware of the situation, and studying the various pro and contra arguments, I agree with the critics of the paper. Therefore, I would like to take the responsibility for this editorial decision and, as a result, step down as Editor-in-Chief of the journal Remote Sensing. -- emphasis added H/t to Michael Tobis for finding this.
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  12. Yes -- the whole thing's worth a read. How will Roy and company spin this one?
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  13. 11, muon, A very interesting article (readers should note that it is not behind a paywall, so go ahead, click the link, and read it all... it's not long, and has some interesting insights).
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  14. Sphaerica, You mean like this? With this step I would also like to personally protest against how the authors and like-minded climate sceptics have much exaggerated the paper’s conclusions in public statements ... Unfortunately, their campaign apparently was very successful as witnessed by the over 56,000 downloads of the full paper within only one month after its publication. But trying to refute all scientific insights into the global warming phenomenon just based on the comparison of one particular observational satellite data set with model predictions is strictly impossible. -- emphasis addded Yep, I think that's a keeper. Bet this poor guy gets some heat from the 'skeptic' crowd.
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  15. 14, muon, Of course. He is clearly stepping down because he was unable to squelch this landmark paper before publication. In fact, he's probably not even really resigning. He's probably being forced out because his bosses know how hard he did try to squash it. Clearly, the peer review process is broken. At the same time, last month was again one of the top 3 or 4 Augusts on record. I wonder if Roy will do what he did in July on his site, which is to spin things to completely ignore the troposheric record in favor of pointing out how cool the oceans appear on average compared to the previous decade. Can you pick up that other end of the goal post and help me move it a little further?
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  16. The UK Guardian has an article too, and John Abraham's quotes are well worth a read here
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  17. As expected, Dr. Spencer flavored this month's temps by pointing out a drop in sea surface temperatures, complete with a non-scientific downward trend line that he includes, but warns is only for "entertainment purposes." He further adds a polynomial fit to the tropospheric temperatures, purely for "entertainment," the implies that we have entered a cooling phase. Go see. It's great denial fun. While you are there, you can look at his response to the resignation.
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  18. Sphaerica The "for entertainment purposes" is very dissapointing. You have to be a real geek to find fitting a polynomial entertaining (and have a poor grasp of the statistical issues), so it can't be that. Surely he must know that there will be some out there that will take it seriously even with the caveat. Now making a semi-serious attempt at a prediction and seeing if it pans out, that would be entertaining.
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  19. 18, Dikran, I'm sure he's well aware that 2/3s of his visitors don't even bother to read and will only look at the pretty pictures. Disinformation mission accomplished, and it's not his fault, is it? Just like it's not his fault that his paper got published and grossly misinterpreted by Forbes or that the reviewers didn't do a good job or...
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