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An Even Cloudier Outlook for Low Climate Sensitivity

Posted on 12 December 2010 by dana1981

Research has given us good confidence that if CO2 doubles in the atmosphere then there will be 1.2°C of directly CO2-caused global warming, and a combination of melting snow/ice and increased evaporation of water will act as positive feedbacks to increase this warming by approximately 1 to 2°C.

This climate sensitivity of an additional 1 to 2°C warming would mean most recent global warming was human-caused and more is in the pipeline; but some scientists believe that changes in clouds will cool us down, though the most public paper to claim this (Lindzen and Choi 2009) has been heavily criticized for using a method that can be fiddled to give any desired result and ignores much of the planet.

The strength of the cloud feedback is commonly calculated by determining the change in cloud-caused heat flow for a change in temperature:

F = ?Rcloud /?Ts

Where "F" is cloud feedback, ?Rcloud is the change in the top of the atmosphere (TOA) flux caused by cloud changes, and ?Ts is the global-average and monthly mean surface temperature anomaly.

Roy Spencer believes these calculations are invalid because we can’t tell whether the warming is changing the clouds or the clouds cause the warming through his hypothesized ‘internal radiative forcing’. If the change in temperature is caused by the clouds in the first place, then we could calculate a positive feedback even if it is actually negative!

A new paper by Dessler (2010) attempts to get around this and calculate the quick cloud feedback using measurements by the Clouds and the Earth’s Radiant Energy System (CERES) instruments from March 2000 to February 2010. The satellite measures how much heat is coming from the Earth at TOA, and Dessler accounts for greenhouse gases, humidity, El Niño Southern Osciallation (ENSO), etc. to determine how much of the heat flow is from clouds. He then looks at how far above or below the average it is for its month, and plots this against temperature.

If the temperature is related to clouds, then you expect a slope in the graph thanks to the above formula. Figure 1 displays the results, and Dessler finds that the short term feedback is 0.54 ± 0.74 (2?) W m-2 K-1, i.e. far more likely to be positive than negative, although negative values can’t be ruled out based on this data.  However, a small negative feedback is insufficient to support the theory that clouds will prevent significant future warming.


Figure 1: (A) Scatter plot of monthly average values of ?Rcloud vs. ?Tsusing CERES and ECMWF interim data. (B) Scatter plot of monthly averages of the same quantities from 100 years of a control run of the ECHAM/MPIOM model. In all plots, the solid line is a linear least-squares fit and the dotted lines are the 2? confidence interval of the fit. 

A key point in the paper is that most of these short-term temperature changes are caused by ENSO.  If the temperature change is being caused by ENSO, then it’s likely not being caused by clouds, and Spencer’s hypothesis is potentially sidestepped.  Spencer has countered this by arguing that ENSO changes are caused by clouds, and thus the response of clouds to surface temperature changes cannot be inferred.  Dessler argues that Spencer's hypothesis that ENSO is caused by clouds is new and untested, and the burden of proof falls on Spencer to demonstrate that his hypothesis is correct.

Dessler (2010) adds confidence that the cloud feedback is not significantly negative, and various climate models are largely in agreement with the CERES observations., as illustrated in Table 1.

Table 1: Cloud feedback values. All uncertainties are 2?.  Feedbacks are calculated from a 100-year  segment of a control run, except for CCSM3, which is based on 80 years.

 

Dessler is careful to point out that there are differences between short-term and long-term cloud feedbacks in models, which suggests that these observations might not be a good guide for the future.  However, although long-term climate sensitivity cannot be determined from 10 years worth of data, the global climate models did pass this test, and the evidence against a strong negative cloud-climate feedback continues to mount.

The paper also comes on the heels of Lauer et al. (2010), which examined and provided support for the high end of current estimates of global climate sensitivity due to a positive cloud-climate feedback.

This guest post was written by Mark Richardson (MarkR) and Dana Nuccitelli (dana1981)

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Comments 51 to 100 out of 124:

  1. HR #49 - again, the article doesn't say Lindzen fiddled or cherrypicked. It says the way he analyzed the data left it open to fiddling or cherrypicking. He could have just chosen a random start and end point, but 'fiddling' with the data to choose a different start and/or end point would give a different result. The method is what's being criticized, not necessarily how he used it. muon #46 - if you argue that some factor besides CO2 is causing warming (like a cloud 'internal forcing', in Spencer's case), that's how you get away with low sensitivity and the 0.8°C warming thus far. I'm not sure how Lindzen explains it - frankly I don't think he does.
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  2. @HR: "The first thing I ever posted on RC was deleted. Same was true at Rohm's website." If it was of the same caliber as the stuff you post here, I can't say I'm surprised, or even disapprove. As the moderator indicated, there's plenty of ways for newcomers to learn the science - not that you are a newcomer by any stretch of the imagination...
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  3. "There exists the search function in the upper left of each page as well as the Arguments page. I used both myself for more than a year before commenting here for the first time." Checking the bible to see what's the right and wrong thing to say isn't to everybodies taste. I'm much happier to jump in and be shown to be wrong.
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  4. 52 archiesteel *sigh* I don't worry about the caliber of what I say, it's surprising how quickly somebody here will jump all over you correct you when they think you're wrong.
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  5. "Checking the bible to see what's the right and wrong thing to say isn't to everybodies taste. I'm much happier to jump in and be shown to be wrong. " I think John would be first to tell you, this site ain't the bible. It's a resource. A damn good one. You should try it some time.
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  6. HR: "I don't worry about the caliber of what I say, it's surprising how quickly somebody here will jump all over you correct you when they think you're wrong. " Why do you find that surprising? If you hadn't noticed there is a political campaign to undermine science, climate science in particular. Your screen name is provocative, without you yourself making a comment!
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  7. HR: "Checking the bible to see what's the right and wrong thing to say isn't to everybodies taste." Again, a provocative statement. You complain, but at the same time provoke.
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  8. Archisteel I put my laziness to one side for a while to read the Trenberth paper (linked in #13). I got a question on that and it's relation to Dessler's method. Hope it ain't too dumb or skeptic or whatever. I'm really unsure whether it's a valid question but hey no harm just jumping in. Can I ask a dumb question? Does the changing atmosphere-ocean heat flux during ENSO make a difference to the scatterplot in Desslers paper? My uneducated climate science brain says it'll introduce a bias to the scatterplot but I don't see anywhere in the paper where it says it's been accounted for? Is the magnitude of the recharge and discharge of heat in the tropical Pacific Ocean large enough to make a difference? I get the feeling from the Trenberth paper that it is.
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  9. HR #50 RC topics are full of skeptical ACC challenges. I am not a skeptic but have had comments at RC deleted. One in particular I recall is where I drew a relationship between ACC denial and two other well established groups. Bottom line, I was off topic and deserved deletion. Sometimes, wake-up calls are needed.
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  10. How can you mention clouds without mentioning heat transfer from the hydrologic cycle? Storm related, violent updrafts and downdrafts are the bane of aviators. Simpson mentions "hot towers" with ambient temperatures at hurricane tops of 10-18C above ambient at up to 18,000 meters in altitude, an altitude where CO2 and other greenhouse gases concentration are much lower than at ground level. From an engineering point of view, storms appear to be giant heat engines , with the heat source in the ocean and other sources of hot water or vapor, and the cooler heat sink in clouds. I have read estimates of a meter of sea water evaporating annually. This represents a mammoth amount of energy. Winds are powered by Coriolis forces of air moving to fill the missing updraft air and in the expanding air moving away from the updraft at cloud tops. -Or so it seems to me.
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  11. Hi all, IMHO, continuing to discussion about alleged censorship and moderation at certain sites is not at all constructive, especially given that doing so does it speak to the science at hand. Could we please focus on the science? My two cents worth.
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  12. #60: "I have read estimates of a meter of sea water evaporating annually. This represents a mammoth amount of energy." Doesn't the bulk of that vapor condense back out and don't we 'recover' the bulk of the energy of evaporation upon condensation? If we had a net loss of a meter of sea water each year and still have measurable sea level rise, we must really be melting some ice! For other evaporation questions, See the thread on Humidity increase
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  13. I'll make an easy statement, too: put up or shut up. Seriously. Go show Dressler where he's wrong. Seconded. Talk's cheap. Stop casting petty aspersions and show your work. As for the people who are complaining about comment moderation at RC, I don't see that RC's commenting policy is all that different from SkS. It's more inconsistent, probably, but it also tends to be more tolerant of "skeptical" conspiracy-mongering and ad hom. Certainly, outright trolling disrupts more threads there than it does here. Still, even if this complaint were accurate, you could avoid having your comments deleted by submitting strictly rational and respectful criticisms of Dessler's methodology. Implying that your criticisms will be deleted makes it seems as though you're simply avoiding a real test of your pet theories. You're fortunate to be have an opportunity to engage with Dessler. Make use of it. You might learn something.
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  14. I wouldn't spend much energy trying to figure out what Roy Spencer's position is really supposed to be as it relates to Andy's paper. I'm afraid that Roy is somewhat narcissistic. Trying to engage the likes of Spencer and Lindzen in meaningful dialogue is simply an exercise in futility. In Roy's own words: " First, we skeptics already know your arguments …it would do you well to study up a little on ours. And second, those of us who have been at this a long time actually knew Galileo. Galileo was a good friend of ours. And you are no Galileo.". Neither is Roy, but he looks good on TV. I've read all the exchange and there is certainly the insinuation by Roy that ENSO is driven by clouds. But who am I to question Roy's science, after all, as he states, everybody else is wrong and only he is right. I find it hard to believe that Roy took the time to break from his politicizing at Cancun to even read Andy's paper. And as has been indicated in discussion, it was totally absurd of Roy to criticize the timing of the release of Andy's paper as these paper's are submitted and the author(s) have no control over the timing of the release, and Roy is quite aware of this. Amazing how people turn to dirty pool when their backs are against the wall.
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  15. it's surprising how quickly somebody here will jump all over you correct you when they think you're wrong. What's even more surprising is how quickly people return to their errors after being corrected. Sometimes it's almost like the discussion never happened, and everyone has to go back to square one.
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  16. @RickG: I get posts deleted here regularly because I get off-topic sparring with tro..."skeptics". I don't mind, those are the rules and I admit I do tend to be combative when confronted with the same debunked argument over and over again (that, and "skeptics" who hide their pseudo-science behind a wall of jargon, formulas and appeals to sources that do not actually support their views). The moderators here do a great job, even if I'm sometimes on the receiving end of their moderation stick. I'm completely fine with that.
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  17. Ron Crouch #64 But who am I to question Roy's science, after all, as he states, everybody else is wrong and only he is right. The last time I paid any attention to Spencer, he was scolding other climate scientists for treating his claims about an 0.5 percent change in cloud cover over the last 30 years as speculative. He actually complained that his colleagues wanted to know what might cause such a change. He really doesn't seem to get that the burden of proof is on him, and that people who make commonplace requests for evidence are not modern-day Inquisitors. Roy is quite aware of this. I wonder if he is. It's amazing what people can forget or overlook when they need to.
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  18. I suggest the text "This climate sensitivity of an additional 1°C warming" should be reworded "This minimum climate sensitivity of 2.2°C warming", as the term "climate sensitivity" refers to both direct and indirect effects of a doubling of CO2. I still worry that we may be underestimating the climate sensitivity. For example, as far as I know the models do not factor in the release of methane from deposits of methyl hydrate. Also, ice core data reveals spikes in temperature between ice ages and interglacials averaging more than 10 degrees C, even though the spike in CO2 between ice ages and interglacials is less than 100%.
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  19. Phila # 65 What's even more surprising is how quickly people return to their errors after being corrected. Sometimes it's almost like the discussion never happened, and everyone has to go back to square one. It's not just sometimes, and that's the real problem. The same debunked arguments are repeated endlessly across the internet, in the press, on talk radio and even in the halls of Congress.
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  20. In http://gmao.gsfc.nasa.gov/pubs/docs/Rienecker369.pdf (the model Dessler used to get the top chart in the post) it seems like the AGCM has no mechanism to use convection and latent heat transfer to estimate the lapse rate. Instead the lapse rate seems to be an input to the model. It seems to me that lapse rate is the most direct determiner of cloud amounts and cloud feedback lapse rate controls convection. My broader question is is GHG warming of the rest of the atmosphere in any model? This question came to mind reading the explanation of GHG warming on the other thread which didn't take into conduction from the GHG to the non-GHG. My understanding is that this happens much more often than the GHG re-emitting radiation that it just received. The equations in the model above don't appear to have that conduction, hence the need to input lapse rate. I don't know how any model can calculate lapse rate without conduction.
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  21. I hope Kooti will respond with some authority here but quickly looking at the pdf, I dont follow you. If lapse rate is an input (no sign of this being the case), how can lapse rate be used for quality check? Convection system is described.
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  22. #72, scaddenp, I'm trying to find the answer to my general question myself, it has something to do with optical depth or thickness I think. For that particular AGCM my understanding is that the model is used to assimilate satellite measurements so they can be used for broader climate and weather studies such as Dessler's. That means it assimilates just the satellite measurements (radiation) and I'm not sure that lapse rate can be derived directly from those measurements (I could be wrong). But looking at the convection system equations, I guess the idea is that because the temperatures are calculated at each layer in the model, that temperature gradient does in fact represent the lapse rate in discrete steps. So I guess it is calculated within the model after all.
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  23. A brief followup: the pdf indicates that the lapse rate is used as one of the predictors for the linear calculation of satellite sensor bias parameters. I take that to mean that lapse rate (derived from the model?) is used as an independent variable in a linear equation which calibrates the sensor.
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  24. Eric (skeptic) #71 My broader question is is GHG warming of the rest of the atmosphere in any model? Eric, any day now I expect to read that you are skeptical of whether climate scientists remember to put their pants on in the morning. But seriously, why not ask some of these questions over at RC?
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  25. 61 Albatross Agreed, let's talk about the science. The scatterplots. The observational data obviously has a lot less data points than the model. Importantly few at the extremes of deltaT. Do those few data points have a larger impact on the slope of the graph than the pile of data points in the middle? Is this part of the limitations of this being only 10 years of analysed data? What are the specific limitations of only having 10 years data?
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  26. #75, Pete, I took your (and others') advice and about the MERRA model at RC. I realized later that my "broader question" in #71 seems silly since one of the main purposes of modeling is to determine temperatures at each layer of the atmosphere. But looking at the equations for convection and radiation, I still don't see the conduction from GHG to nonGHG. Maybe it is so basic I missed it elsewhere in that pdf.
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  27. Eric @70, "....(the model Dessler used to get the top chart in the post) it seems like the AGCM has no mechanism to use convection and latent heat transfer to estimate the lapse rate" The top panel of the chart you refer to is based on ECMWF-interim (reanalysis) data. Are you referring to the ECHAM AOGCM? If so, why a link then to the NASA GEOS-5 assimilation model? I'm not not seeing what your thoughts have to do with Dessler's paper.
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  28. HR @75, "Do those few data points have a larger impact on the slope of the graph than the pile of data points in the middle?" That is a possibility. But is hard to say without having access to the data. Dr. Dessler realizes that there is not much data here-- even thought the ECMWF-interim data go back to 1989, CERES was launched on board NASA's Terra satellite in late 1999 (apparently a CERES instrument was launched on board TRMM in late 1997, but I'm not sure why they did not use those data, maybe there were issues with the early instrument?). Given the relatively limited data (120 data pairs), Dessler has answered your question when he says: "Obviously, the correlation between DRcloud and DTs is weak (r^2 = 2%), meaning that factors other than Ts are important in regulating DRcloud. An example is the Madden-Julian Oscillation (7), which has a strong impact on DRcloud but no effect on DTs. This does not mean that DTs exerts no control on DRcloud, but rather that the influence is hard to quantify because of the influence of other factors. As a result, it may require several more decades of data to significantly reduce the uncertainty in the inferred relationship." My read of this paper is that it is a sincere and honest effort to address an important, but vexing, problem in climate science. I have to yet come across the "ideal" data set in my field, you do the best with what you have. Dessler has developed and tested a methodology which can be applied in the future as more data becomes available. That, contrary to what Dr. Spencer might believe, is a step forward for science-- something that Dessler seems genuinely concerned and passionate about. The novelty and strength of this paper lies in the fact that, unlike LC09, Dessler is looking at global data and that his approach implicitly includes clouds of all types (i.e., other studies have focused on just low clouds, for example). Finally, this paper, demonstrates that the models are (in the short-term at least) actually doing a decent job in simulating the cloud feedback the short-term, and is also further evidence that (while not discounting the possibility of a very weak feedback) that a cloud feedback is in all likelihood positive, with an approximate 95% confidence interval (equivalent to about 2 sigma) of the mean of +0.54 W/m^2/K between -0.2 and 1.3 W/m^2/K. I would also suggest reading the very last paragraph of his paper starting with "For the problem of...".
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  29. Spencer's argument is basically "I'm right and Dessler is wrong because I think clouds cause ENSO, a hypothesis I'm throwing out there based on no real evidence, and contradicted by all studies on the topic to date".
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  30. #77, Albatross, no I am referring to the GOES-5 assimilation system called MERRA which is an AGCM. Essentially as far as radiation, cloud processes and convection goes, Dessler compared a GCM to another GCM. The difference is that the MERRA AGCM assimilates the GEOS satellite data so the model numbers match reality. But that doesn't mean that internal modeled parameters like the clouds or their feedback in warming scenarios match reality. In the top figure in the head post, there is a scatterplot resulting from an AGCM and in the next figure, a scatterplot that results from the other GCMs and AGCMs. Since they use much the same equations for their dynamics, the scatterplots should be similar.
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  31. Eric, I believe the process of conductive energy transfer is embodied within the solution to the RTE which model does. Had a look at Ramanathan and Coakley 1978 for the gruesome mathematical detail.
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  32. scaddenp, thanks for that paper. It's going to take a while to read.
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  33. Eric @80, Not to be a pain, but you originally referred to the the "top chart in the post". That figure is Fig. 2 in Dessler (2010), and the figure caption makes no mention of MERRA: "Fig. 2. (A) Scatter plot of monthly average values of DRcloud versus DTs using CERES and ECMWF interim data. (B) Scatter plot of monthly averages of the same quantities from 100 years of a control run of the ECHAM/MPIOM model. In all plots, the solid line is a linear least-squares fit and the dotted lines are the 2sigma confidence interval of the fit." The model at the heart of the ECMWF interim, is IIRC, a similar version of their operational global NWP model. So I do not know why you are focusing on MERRA and the AGCM used in the GOES-5 data assimilation system.
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  34. 78 Albatross Thanks, part of the problem is this is a Science article which means much of the detail is omitted, not even any SI. r^2 = 2%. I work primarily with well controlled laboratory experiments. r^2 is generally well over 90%, when things start dropping below this we're worrying about reproducibility. r^2 of 2%, and being satisfied with that, are beyond my comprehension. I know why it's happening, this is a complex, uncontrolled experiment, I just don't understand what that does to the certainty behind the result.
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  35. 79 NewYorkJ If that's all it takes to get published in JGR then I guess we should all have a go. "I think clouds cause ENSO" Can you quote from Spencer's paper where he makes or infers this? (it's linked in the article) In fact he states the following as the drive behind the paper. "The central issue we will examine is that satellite measurements of variations in radiative flux contain a mixture of forcing and feedback and the presence of one will affect the identification and estimation of the other. Our specific interest is a better understanding of the impact that unknown levels of time‐varying radiative forcing have on feedback diagnosis and what that might mean for the estimation of climate sensitivity." Maybe we could also discuss what Spencer is trying to do here rather than what you (or Dessler) think he is doing. From the Spencer paper I couldn't actually see any estimate of short term feedback.
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  36. Oops, sorry, hit return too soon. You also say that "The difference is that the MERRA AGCM assimilates the GEOS satellite data so the model numbers match reality" Both ECMWF-interim and MERRA assimilate satellite data, which includes data from the GOES sounders, and other satellite platforms. Above I said "GOES-5", which should have been "GEOS-5"-- they are even confusing me with their acronyms. For what it is worth, ECMWF-interim is considered to be the Rolls-Royce of all the reanalysis products (e.g., NCEP, NCEP-DOE, JMA etc.), although it would be nice if they could match the 0.5 degree grid spacing used in MERRA. I'm surprised that it does into bother you that Spencer and Braswell used a much, much more simplistic model in their recent paper on feedbacks in JGR. In fact, it did bother Murphy and Forster, so much so that they wrote a paper, Murphy and Forster (2010) back in September 2010, in which they summarize some serious problems and consequences related to Spencer and Braswell using that simple model. Murphy and Forster conclude: "This paper shows that Spencer and Braswell overestimated the difference. Differences between the regression slope and the true feedback parameter are significantly reduced when 1) a more realistic value for the ocean mixed layer depth is used, 2) a corrected standard deviation of outgoing radiation is used, and 3) the model temperature variability is computed over the same time interval as the observations. When all three changes are made, the difference between the slope and feedback parameter is less than one-tenth of that estimated by Spencer and Braswell." The outlook for those trying to argue for a marked negative cloud feedback gets cloudier and cloudier.
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  37. I obviously need to get some sleep. Murphy and Forster (2010) was written to address problems with Spencer and Braswell (2008), not Spencer and Braswell (2010). Sorry. With that said, it looks like Spencer and Braswell (2010) used the same, or similar, simple model used in Spencer and Braswell (2008).
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  38. HR, "when things start dropping below this we're worrying about reproducibility. r^2 of 2%, and being satisfied with that, are beyond my comprehension." Dessler is clearly not "satisfied with that" as you claim, please read the quote again carefully. The climate system is obviously not the controlled lab setting with which you are familiar. Although, I agree that 2% is extremely low, even for 120 data points, and even in the realm of feedbacks when r^2 tend to be relatively low. Then again, one doesn't need to change cloud cover much to have a marked impact on the energy budget of the climate system. And remember, that low r^2 applies to anyone working on this problem (including Spencer) and trying to extract a signal from noise in the system.
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  39. HR the coefficient of determination need not be high; if the dependent variable depends on many factors you won't get a high r^2 anyways. As Dessler says "This does not mean that ΔTs exerts no control on ΔRcloud, but rather that the influence is hard to quantify because of the influence of other factors". Having said this, I'm sure no one is "satisfied" with a non statistically significant result, but what a scientist must do is to obtain as much informations as possible from the available data. Dessler conclude that the feedback is probably positive, a large negative feedback is very unlikely and that models do a decent job. This can be said even with a low r^2.
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  40. Albatross (#83), I was incorrect in #80 (answering your #77). I read the paper body (p. 1525) and forgot about the caption where Dessler only plotted ECMWF, not MERRA. When I looked them up originally I found the MERRA tech report which explained assimilation very nicely so I used that. I need to find a similar reference for ECMWF. Both "reanalyses" (i.e. models with data assimilation) are used in the same way for his conclusion (the models with real world data matches the models without). My argument is that the cloud parameters are internal (at least in MERRA) and therefore depend on the radiation, convection and cloud process equations plus an assortment of parameters which are determined by fitting the model to the real world data. I think my argument will apply to ECMWF, but I will have to look that up to find out their model details, particularly for clouds. Sorry about the confusion (starting with my #16). Obviously I need to look at Spencer next. I am pretty sure that you are correct that his model is too simple and that his model assumptions are what creates his result independently of the real world measurements. I'll also try to evaluate how he states and tests his hypothesis. Dessler was quite clear about his.
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  41. HR, This should be obvious in their exchange: http://geotest.tamu.edu/userfiles/216/emailExchange.pdf http://www.realclimate.org/index.php/archives/2010/12/feedback-on-cloud-feedback/
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  42. Yep...Spencer is definitely saying clouds are initiating ENSO in that exchange. The mechanistic sequence is not really explained though. Nature paper there if he can convince anyone...
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  43. Yes, it's very clear. Over at RC Dessler made it clear that it was this e-mail exchange that convinced him that Spencer really *is* arguing that clouds are driving ENSO. He speaks specifically of satellite data showing causation in a recent La Niña, and that it's clouds=>temperature.
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  44. 91 NewYorkJ 93 dhogaza You could also try this on Spencer's blog I'll even copy the relevent bit for you "To Dessler’s credit, he actually references our paper. But he then immediately discounts our interpretation of the satellite data. Why? Because, as he claims, (1) most of the climate variability during the satellite period of record (2000 to 2010) was due to El Nino and La Nina (which is largely true), and (2) no researcher has ever claimed that El Nino or La Nina are caused by clouds. This simple, blanket claim was then intended to negate all of the evidence we published. But this is not what we were claiming, nor is it a necessary condition for our interpretation to be correct. El Nino and La Nina represent a temporary change in the way the coupled atmospheric-ocean circulation system operates. And any change in the atmospheric circulation can cause a change in cloud cover, which can in turn cause a change in ocean temperatures. We even showed this behavior for the major La Nina cooling event of 2007-08 in our paper! It doesn’t mean that “clouds cause El Nino”, as Dessler suggests we are claiming, which would be too simplistic and misleading of a statement. Clouds are complicated beasts, and climate researchers ignore that complexity at their peril." These are Spencer's words, not Dessler's interpretation of Spencer's words. It can't be any clearer that he does not hold the view that Dessler assigns him. I understand what Spencer is saying here and I'm not a climate scientist. He's not arguing clouds cause ENSO, he's questioning the assumptions about the relationship between clouds and temperature. In Spencer's first email he says clouds proceed temperature, not clouds proceed ENSO. It's Dessler that seems to think that this means ENSO is caused by clouds. My reading of Spencer's work is to try to understand what he calls "internal radiative forcing" and other's call "unforced internal variability". This isn't just his theory, what's novel about Spencer's work seems to be in the understanding of how these processes affect the measurement of short term radiative forcing. While Spencer goes off on a flight of fancy about the timing of the publication, and should really hold his head in shame over that, I do think he has a point about Dessler's use of the "clouds cause ENSO" arguement. The power of that arguement is to place Spencer so far outside the mainstream as to discredit everything he says. It's no more worthy a tactic than Spencer's conspiracy theory and no better at discrediting the science.
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  45. To put it simply I think Dessler thinks A) ENSO causes temperature change which causes cloud changes which cause further temperature changes. A classic feedback situation While Spencer is proposing some role for B) ENSO causes circulation changes which cause cloud changes which causes temperature changes. Unforced internal variability I'm not sure Spencer is proposing the first one does not exist just that what is showing up in the data set is a mixture of both. It's this that makes Desslers (and others) methodologies different from Spencer's. Anyway I'll post this on Spencer's blog to see what he has to say.
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  46. The question HR is why does he clearly hold one view when talking to Dessler and another when blogging to the public. The point that Dessler is making in the emails is that if ENSO is initiated by ocean-atmosphere interactions, and if this leads to cloud formation that reinforce that change, then that is a feedback. It is the magnitude of that very feedback that Dessler is trying to measure. When confronted with that reasoning in the emails, Spencer argues that the clouds initiate ENSO by affecting surface temp so as to avoid admitting that clouds are acting as feedbacks. In the quote you provide above from his site, he seems to be talking about clouds as a feedback mechanism, which essentially means Dessler is correct in his approach. He seems to realize (and take advantage of)the fact that he is talking to an audience who is not aware of the important distinction between clouds as initiators and clouds as feedback mechanism, and therefore who won't realize that he is backing into a corner.
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  47. HR, I think that you might also be going off on a "flight of fancy" when you suggest "The power of that argument is to place Spencer so far outside the mainstream as to discredit everything he says". I would argue that Spencer's behavior and comments in recent years (many of which were made on his own blog) are in fact doing just that (i.e., discrediting him). Dessler strikes me as a sincere person who is not likely to engage in the tactics that you are accusing him of. Also, I do not see Dessler et al. holding a press conference the very minute a "skeptic" paper is officially released in order to try and sabotage it. It is Spencer who is playing games, not Dessler. The logic of the contentious statement that Spencer made in his email definitely suggests that for the 2007-2008 La Nina, changes in clouds preceded changes in temperature. Now in Spencer's defense, it was an email, which is a horrible medium for communicating sometimes. Maybe he was simply not clear or mis-spoke. What I do not understand is why Spencer has not spoken up to clarify his position since Dessler made his post at RC, or why he did not take the opportunity to discuss the matter further by email with Dessler. This whole ENSO fiasco is just a distraction though. Dessler's main points are that the cloud feedback in response to warming is very likely positive and that the models are doing a pretty good job in reproducing this short-term (positive) feedback. Anyone still trying to claim that climate sensitivity is low, is on incredibly thin ice-- some might even go so far as to say that they are already flailing in the water.
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  48. Stephen @96, Interesting perspective and insights. Of course another possibility is that Spencer let the "truth" slip in his exchange with Dessler (i.e., let slip his true feelings on the issue).
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  49. This is somewhat OT but related to climate sensitivity. Remember the news last week about the NASA study showing negative feedbacks from plants that bring climate sensitivity down to 1.64C? Potholer54 on youtube has done a great video debunking that myth. If you haven't heard of Potholer54 for before (aka journalist Peter Hadfield) definitely check out his other videos. He's the kind of quality journalist this world is severely lacking these days.
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  50. HR @94, It sounds to me like Spencer is just nitpicking semantics. Temperature change is one of the chief characteristics of ENSO, and Spencer is clearly arguing that this temperature change is initiated by clouds. That view is indeed outside of the mainstream.
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