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Comments 41351 to 41400:

41351. StealthAircraftSoftwareModeler at 13:30 PM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       John Hartz @184: Oh, I would. I wouldn’t do anything like contact GISS. Why would they waste their time talking to me? I understand that.

       Your link to CM101 is broken, by the way, but I found it with Google. In looking at #2 “Understanding Computer Models” – I have some experience with every one listed, and enormous experience with some (i.e. flight simulators). The 101 video was extremely simple; I’m sure it is aimed at the masses, but remember I am a software modeler with a computer science and physic degree and 30+ years of experience. I’m looking for a lot more meat and the details. The devil is always in the details.

       I’ve got Chapter 9 printed out. Hate that I nearly killed a tree, but I skipped all the references in the middle, and printed two pages per page, so that saved a bunch of paper.

       Moderator Response:

       [JH] The most prominent feature of the Climate Modeling 101 website is the National Acadamy of Scinces report, 

       A National Strategy for Advancing Climate Modeling

       I highly recommend that you study this report if you are sincere in your stated goal of better understanding how global climate models work. 

41352. scaddenp at 12:58 PM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       "There has to be a way of telling the model about..." well of couse there is. Forcings are input into the model. The CMIP experiment is about getting the different modelling communities to run the same forcing experiments and comparing results. The forcings to use are on the site but I see it is still down due the goverment shutdown.

41353. John Hartz at 12:41 PM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM @ 179:

       I highly recommend that you do more homework about GCMs before you begin to correspond with various modeling groups.

       In addition to reading Chapter 9 of ARM 5, you should careful go through the Climate Modeling 101 website created by the National Academy of Sciences.  [Link fixed - I hope.]

       http://www.nap.edu/catalog.php?record_id=13430    

41354. StealthAircraftSoftwareModeler at 12:35 PM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Moderator PW @179: So it is okay for Dikran to accuse me of Dunning Kruger syndrome, and state I haven’t bothered to find out about models – which is EXACTLY why I’m on this site. Then he states I think my field is better than climate modeling, when I’ve said no such thing at all! He can kick me all over, tell me to read up climatrology, which has nothing to do with anything in this thread and try to send me on wild goose chases. That isn’t obfuscation? C’mon.

       BTW, what question have I failed to answer and is being noted and tracked? I apologize if I missed one, but trying to discuss things with an angry mob can be confusing.

       Moderator Response:

       [JH] You came to this website with a chip on your shoulder. If you lose that, people will respond to you with civility. 

41355. StealthAircraftSoftwareModeler at 12:11 PM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Scaddenp @180: Thanks for the links. I’m downing loading AR5 Chp 9 now for a trip tomorrow. I have about 6 hours of captive time for a bit of reading. Ugh, 207 pages, but I’m sure it will be easy reading [sarc].

       What I mean by “inputs for volcanic climate forcing” is: If in 1990 for the FAR they run a GCM from 1990 until 2090, then the models would not properly project the large temperature drop around 1992. How could it, no one knew that Mt. Pinatubo would erupt before it happened. Then, for the SAR report in 1995 and after Mt Pinatubo, the models are run again from 1990 until 2090, but this time they have “injected” additional data into the model with estimates of aerosols from Mt Pinatubo. This, of course, causes sunlight to reflect and the temperature takes a big dive. The models show this effect, so assuming the physics haven’t changed from 1990 to 1995, then there has to be a way to tell the model about a specific large eruption. Without that additional input data, I would think the model would produce the same result as in 1990, assuming the model is deterministic, which may not be the case. This is not a complaint, just an observation. Some of you are so jumpy and ready to pounce on me, that I’m starting to qualify a lot of what I say.

41356. scaddenp at 10:56 AM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       If you are putting a lot of thought into evaluating of climate models, then I hope you are also putting a lot of reading into Chp 9 of AR5 which precisely about this. if you want to know about models are made, then why not read the primary literature first instead of speculating?

41357. scaddenp at 10:53 AM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM - As pointed earlier, some/lot of this is in FAQ on climate modelling at Realclimate (where you can ask the GISS modellers).

       FAQ- 1 and FAQ - 2

       I am a little puzzled about what you mean about "inputs inserted in models for volcanic forcings". The big point about Pinatuba, was models forecast what an eruption like that would do (Hansen at al 1992) and then after the eruption (put in actual forcing), confirm the result (Hansen et al 1996). The only thing you "add" to model is the actual forcing in terms of aerosol load. The response to the forcing was already in the model. So models say "If you get X aerosol loading, then you should get Y responses". When X actually happens, you put in actual loading and compare output with observations. I dont think models have "random" forcings. In running a projection for next 100 years, you have to put in "random" volcanoes" at the rate you expect to get eruptions to happen historically otherwise model runs too warm. Noone expects that eruptions will actually happen at those dates, but if eruption rate matches historical norm, then 30 year trends should be predicted. Is that what you mean?

41358. chriskoz at 10:05 AM on 18 October 2013
       Science of Climate Change online class starting next week on Coursera
       

       Hi David,

       Thanks for that course. I was a fan of your Modtran model. I'm looking forward to some good in-depth learning of Carbon cycle (i.e. 3 stages of ocean sink as I learned them from Archer 2005) and experimenting with the new models. Perfect content and perfect timing for me.

       Thanks again

41359. StealthAircraftSoftwareModeler at 09:48 AM on 18 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Dikran @178: I’m ignoring most of the accusations you make and all of your sidelobe jamming, except for the accusation of boasting, hubris, claiming my field is superior, and “not trying to find out what climate models involve”. Huh? That is exactly what I am trying to do on this site, but it has been circuitous due to (-snip-).

       Geeze. I admit I have asked pointed questions, and part of this is to get you all to respond and defend the science. I am not exactly sure of what to look for, but your defense helps me figure out what I need to examine, and now I have a much better idea. Thanks!

       Question 3: I retract my comment about being suspect about retro active adjustments to the models. It was late and I was tired. What I really meant to say is: clearly some sort of inputs are inserted into the model to properly force climate responses to volcanic eruptions. This is a completely reasonable thing to do, but my question is about other input adjustments that are injected into the models in the past to “get them to balance, or to reproduce observed results.” I am curious if (note, this word “if”, as in “maybe”) there are any of those types of input adjustments, and if so, what are they and why are they done.

       I think this thread is winding down for me. I doubt anyone here can answer the questions I now have because you do not know enough about how the models are built. If I’m wrong and you do know a lot about how the models are built, I’d love to talk to on the side and offline. I have given more thought about how to test climate models, and the best would be to make projections and measure the results against real world measurements. Unfortunately, the issue with this is the amount of time it takes. Currently, I think a subsystem analysis of the various components of the model is the best that can be done. I would like to see what GCMs predict/forecast/project for major climatic components, not just air temperature. Here is a summary of what I am looking for:

       I am looking for the forcing input adjustments used to represent volcanic and other random forcing. I would like to see model global projections (mean, 97.5%ile and 2.5%ile) from 1950 for air temp for multiple altitude layers, sea temp for multiple depth layers, humidity or water vapor by altitude layer, global cloud cover, and precipitation. I would also like actual measurements of these values.

       Moderator JH @ 171: If you have any contact information for the organizations that develop and maintain the GCMs, I would like that. I assume you do not want to post their email and/or phone numbers. You can email the information to my email that I used to sign up on this website (it is a real email address, and please keep it private).

       Moderator Response:

       [PW] Accustations of impropriety removed. Your further reluctance to answer direct questions also noted.

41360. Fergus Brown at 07:38 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       Composer at #5; Yes, this is the elephant. The UN already hits the spectrum of politicised polemic in the USA (I don't think too many other countries have the same track record of disavowal). Such a process would simply draws cries of 'Lo the Antichrist rises' and similar nonsense. It would be changing one punchbag for another. But would it be a better means of providing a context for policy decisions?

41361. scaddenp at 07:16 AM on 18 October 2013
       Temp record is unreliable
       

       As I understand the question, it means the questioner expects upper atmosphere to warm. This is a misunderstanding about how the greenhouse works. In fact, the stratosphere is predicted to cool. You might like to look at SoD article on why though though there a number of other resources. However, most deniers are looking for a convenient excuse to ignore science and are unlikely to put the effort needed into understanding this.

41362. Tom Curtis at 06:22 AM on 18 October 2013
       Temp record is unreliable
       

       dvaytw, in response to the statement that:

       "... if anyone wants to claim that CO2 levels in the upper atmosphere are causing ground level increases in temperature, there would need to be much greater warming there, which is demonstrably not happening"

       I would point out that, first, "skeptics" greatly exagerate the expected amount of warming due to CO2 (and other anthropogenic factors); second, scientists have always expected that other short term factors will cause fluctuations in the increase of temperature so that, over short periods it may be much less than is expected over the long term, or even negative; and that third, a very powerfull short term factor is known to be depressing the rate of temperature decrease, and in fact accounts for nearly all of the discrepancy between the actual temperature increase and that predicted by the models.

       With regard to the exageration of the expected rate of warming, this is typically done with graphs such as this one by Murry Salby:

       

       Such graphs may be created in ignorance, by simply scaling the (smoothed) CO2 and Temperature graphs to have a common standard deviation.  Such a scaling ignores the fact that annual fluctations in CO2 concentration are too small to significantly effect global temperature, and so on short times variations in CO2 are not expected to match variations in temperature.  As a result the scaling does not reproduced the expected temperature increase.  That mismatch is exagerated if the match is done between annual (or worse, monthly) temperature variations and a smoothed CO2 curve as done above.

       In some instances, however, including that of Salby, the exageration must be deliberate.  That is because the same authors show graphs of the expected temperature increase as a function of CO2 concentration over the coming century.  As a result, when they show the short term "prediction", they must know that they have changed the relative scales of CO2 concentration and temperature, thereby mistating the predicted increase in temperature from the increase in CO2.  This can be seen by comparing the prediction at the scale used for centenial predictions with that used over the last few decades:

       

       As can be seen, with an honest scaling, recent temperature increases have closely matched those predicted by the IPCC Assessement Report 4 (AR4).  To avoid any misunderstanding, however, it should be clear that the "prediction" above is produced by simply using the same scale ratio between CO2 and temperature as is used in Salby's centenial comparison, and slightly understates the actual AR4 short term prediction, which was for 0.2 C per decade.  Salby's graphic manipulations are discussed in more detail here.

       With regard to the expected short term fluctuations, that can be seen in the temperature record up to 2005 (when the short term temperature trend met or exceeded IPCC predictions).  During that period, however, there are many short term periods with zero, or slightly negative growth:

        

       Climate scientists are not utter fools.  They can read temperature graphs as easilly as anyone else; and could see, therefore, that a prediction of temperature increases without faltering (ie, monotonic increase) was already falsified, and would not be so foolish to frame their predictions in a fashion that was already falsified.  The assumption that a short term low trend in temperature increase somehow falsifies AGW, however, tacitly assumes that they were such fools, for it assumes a "hiatus"not greatly different from "hiatuses" that occured before the predictions will falsify AGW.

       Nor do climate scientists predict short term fluctuations merely to save appearances.  In the CMIP5 model intercomparison for IPCC Assessment Report 5, using the scenario with the strongest warming (RCP 8.5), over 8% of 15 year trends with a start year of 1970 or later, and and end year of 2015 or earlier are smaller than the HadCRUT4 trend since 1998.  Indeed, 4.48% are negative and there is one 15 year trend of negative 0.15 C per decade.  The prediction of short term fluctuations and hiatuses comes from the models themselves.  They are not ad hoc afterthougths.  They do not typically show up in statements about predictions because they represent short term chaotic factors that have no influence on the long term trend.  Consequently they do not coordinate in position across all models in the ensemble, and do not appear in the ensemble mean.  Indeed, the lowest 15 year trend in the ensemble mean over that period is more than twice the HadCRUT4 trend since 1998; but that is because the ensemble mean has eliminated short term non-forced fluctuations while the real world has not.  Climate scientists know this, indeed insist upon it.  So-called "skeptics", however, blur the distinction whenever possible.

       In this regard, it is worthwhile noting that the peak temperature of the 1997/98 El Nino was 0.6 C warmer than the La Nina years on either side of it (see first graph).  That is the equivalent of three decades global warming.  With ENSO introducing such large fluctuations into short term temperature trends, it is impossible that trends of less than thirty years should consistently show trends near to the long term trend.

       Finally, there is, in fact, a known short term non-forced factor that accounts for nearly all of the discrepancy between predicted and observed short term trends.  Given the comment in my last paragraph, it will come as no surprise that it is ENSO:

       

       Very clearly, ENSO has had a strong negative influence on the temperature trend since 2006, and arguably since 1998.  That ENSO is the major driver of the recent temperature "hiatus".  In fact, three very clear lines of evidence demonstrate that beyone reasonable doubt IMO.  They are the fact that if you only examine the trends in ENSO equivalent years, all trends are nearly the same and close to that predicted by the models; that if you adjust temperatures for known ENSO states,the result is a trend close to that predicted by the models, and finally, if you constrain a model to match the historical ENSO pattern, it reproduces the historical temperature record.  I discuss these points in detail here.

       It should be noted that ENSO is not the only known factor that helps explain the reduces recent trends.  Tropical volcanism is known to have increased the aerosol load, a factor that should induce cooling if not for a countervailing warming trend.  We are also experiencing unusually weak solar activity, which should also have the same effect.  Other factors may also have influence, and scientists are examining these factors, and others to determine the relative importance of different factors.  But ENSO is the main factor, without doubt.  It is sufficiently strong a factor that, if CO2 forcing did not have a significant warming effect, we should be experiencing a significantly negative short term trend in global temperatures, not the weakly positive trend we are currently experiencing. 

41363. Rob Nicholls at 04:30 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       Is frequency of IPCC reports really the issue? How much have things really changed between AR4 and AR5? I've never had a sense that AR4 was very out of date or very far off the mark in the last few years. One of the things that I like about IPCC Assessment reports is that they're done properly. I've never read such an awesome synthesis of a complex subject anywhere else. I wouldn't mind seeing them done more often if they're going to be as good quality.

       More importantly, humanity ought to fund the IPCC properly, particularly if the IPCC is going to start producing more products, in more innovative ways (and, if needed, more often). I find it incredible that IPCC ARs, which are of such massive importance to the future well-being of our species (and many others) are written largely through voluntary efforts of already very busy scientists (although certain commentators will have us believe that climate science is just one big gravy train, I've never noticed science as being a particularly lucrative career, and I can imagine that the overall hourly rate is rather low, especially for those hundreds of experts who selflessly give up their time to work on IPCC assessment reports.)

       The IPCC could really help us prevent a whole of trouble in the future, so it ought to be much better funded.

41364. jja at 03:52 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       You absolutely need to update AR5 figures 6.25 and 6.27. 
       
       6.25 -Compatible fossil fuel emissions simulated by the CMIP5 ESM models for the 4 RCP scenarios
       
       This figure needs to be updated to show a 2-sigma uncertainty.  A 68.2% uncertainty band is doing us all an incredible disservice.
       
       6.27 -Compatible fossil fuel emissions for the RCP4.5 scenario (with and without carbon cycle feedbacks)

        

       This figure needs to be updated to show 2-sigma uncertainty as well as RCP 8.5 scenarios.
       
       I understand why a 2-sigma uncertainty wasn't shown, because of the fat tails of carbon cycle feedbacks and equilibrium climate sensitivity uncertainties.
       
       The risk associated with the potential for a 2-sigma error are so great, it is vital that these uncdetainties are reflected in the AR5, even if the authority of the report may seem diminished.  This is a scientific exercise, not a political one.
       
       in other words.  would you propose that the designer of a nuclear power plant only use a 1-sigma uncertainty for the integrity of the reactor pressure vessel, so that her calculations appear to be very precise and authorative?  NO, of course you wouldn't.
       
       well, the RCP 8.5 ECS and climate cycle feedback uncertainties directly affect potential mitigation solutions.  If we don't take that into account then our hopes to adequately address them will fail.  With results that are many orders of magnitude worse than a total nuclear power plant meltdown.

       Moderator Response:

       [JH] Is your request directed to the IPCC or SkS?  

41365. Dikran Marsupial at 02:36 AM on 18 October 2013
       CO2 lags temperature
       

       dvaytw, you would need to be a bit more specific about which events you have in mind.  keysersoze's comment at 70 was pretty vague, but I suspect he meant the Paleocene-Eocene Thermal Maximum (PETM), in which case the recovery wasn't nearly as rapid as he suggests, according to Wikipedia (yes, I know) the Earth cooled again over a period of 120,000 years which is not at all brief in relation to the 800 year lag time in the question.  A timespan of 120,000 years is a bit brief to be fully explained by weathering, but not by a huge amount.

       The other problem with keysersozes question is that the existence of feedback does not necessarily mean that there is runaway feedback.  In the case of the carbon cycle, equilibrium temperatures rise only logarithmically with rising CO2 (which is slow), but the rate at which the oceans degass goes up linearly with temperature, so immediately there is a case of diminishing returns.  Also the solubility of CO2 in the oceans increases with increasing atmospheric concentrations, which makes it progressively more difficult for CO2 levels to rise substantially naturally (other than due to volcanos or methane releases etc.).  The positive and negative feedbacks involved keep the carbon cycle quite well balanced unless perturbed by some external forcing.  These positive and negative feedbacks tend to bring the carbon cycle back into line automatically if left alone.

41366. dvaytw at 01:57 AM on 18 October 2013
       CO2 lags temperature
       

       Back at #70, the moderator said:

       Response: Good question - I considered addressing this in the original article above but opted to keep things simple and address it in a future post. In the case of Milankovitch cycles, just as orbit changes initiate the warming, they also end the warming. Towards the end of the deglaciation, orbit changes cause the amount of June sunlight falling on the northern land masses to change by several tens of percent (not an insignificant change). Gradually over time, northern ice sheets start to grow again.

       For greater time scales (eg - over millions of years), rock weathering is another factor that keeps the climate regulated. Rock weathering is the phenomenon where CO2 is scrubbed out of the atmosphere by chemical reactions with rock surfaces. As temperatures warm, the rate of rock weathering increases - this acts as a natural thermostat to keep CO2 levels from getting too high. However, this process occurs over millions of years so don't expect rock weathering to bail us out of our current situation (although interestingly, there is research into using artificially accelerated weathering as a technique in sequestering CO2).

       I'm wondering if there have been any follow-up articles on the topic of what brought our climate back out of Greenhouse Earth periods.  I haven't read through the entire comments section yet, so sorry if this has already been addressed.

       Moderator Response:

       [JH] You may also want to try using the SkS search engine to identify articles that address your topic of concern.

41367. r.pauli at 01:30 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       Need a Ministry of Climate Information... one can see daily information that's important. 

41368. Paul Pukite at 01:30 AM on 18 October 2013
       Science of Climate Change online class starting next week on Coursera
       

       To join in on all the interesting ways of presenting interactive information, I have been adding climate models to my environmental context model server:

       http://entroplet.com/context_salt_model/navigate

       This particular example demonstrates how natural fluctuations contribute to the temperature pause.

       Archer has certainly been improving his online apps, as the Modtran interface has gone through an upgrade.    Other good online applications include Climate Explorer, of course the ones here at SkS developed by Kevin, Nick Stokes' Moyhu work,  and WoodForTrees.

        

41369. Composer99 at 01:24 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       Fergus:

       As a matter of policy I think your idea is a very good one, in that incorporating IPCC reporting into wider UNEP policy documents is a useful (if time-consuming) process.

       I doubt, however, that it would do much to end unconstructive pseudo-debate or convince self-styled skeptics to lay down their rhetoric. The UN and its branch organizations are not, to my knowledge, well-received among the circles that self-styled climate skeptics appear to prefer.

41370. Fergus Brown at 01:04 AM on 18 October 2013
       Time to change how the IPCC reports?
       

       Since the IPCC sits in the net of UNEP, and since many of the UNEP reports deal with managing future change in general, perhaps it is time to consider incorporating a number of Earth and environment reports, including the IPCC one, into a more encompassing, multi-disciplinary five year report card on the state of the planet. Though I'll be honest the logistics would be mind-numbing. 

       This would allow the IPCC to continue a version of it's long-standing review of recent developments in climate change, in particular WG2, but in a context of how this fits in with all the other issues facing the planet and our stewardship of it. It might also divert some of the rabid politicisation of the suppoed 'debate' on climate, which has descended in many ways into a playground punch-up.

41371. dvaytw at 00:49 AM on 18 October 2013
       Temp record is unreliable
       

       Thanks guys for all the tips.  My initial tactic was to point out to him that there are so many temperature records showing the same basic pattern; if the measurement system were flawed, errors would be in all directions and there wouldn't be such obvious similarity between them.  I also pointed him to a very useful pair of charts: on Wikipedia, 'temperature records by countries'.  A quick glance of the 'hottest temperature records' vs. 'coldest temperature records' shows that the former outnumber the latter by a large margin in the last couple decades.  So even just looking at that, the trend is pretty obvious.  
       
       I have another question, but I don't want to keep bothering y'all for answers, so maybe you could just direct me to the most pertinent article, in response to this point of his:

       // ...if anyone wants to claim that CO2 levels in the upper atmosphere are causing ground level increases in temperature, there would need to be much greater warming there, which is demonstrably not happening. //
       
       PS - Moderator, please feel free to delete any of my "please help me with debate" questions to the forum if you feel they are off-topic or don't contribute to the discussion!  Thanks in advance!

       Moderator Response:

       [JH] We welcome your posts and others like them. The comment threads should, in an ideal world, function as a classroom where honest questions are asked and honest answers are given.

       If you have a question and cannot find an appropriate thread to post it on, feel free to post it on one of our "open threads", i.e., the Weekly Digest or the Weekly News Roundup.

41372. Manwichstick at 23:42 PM on 17 October 2013
       Understanding the pre-IPCC Anti-Climate Science Misinformation Blitz
       

       In Toronto, a meterologist posted a piece critical of the 5th IPCC report in late September.

       I posted this rebuttal on a science-based skeptic website:

       http://www.skepticnorth.com/?p=11727

       I would like any feedback the SKS crew can provide regarding my analogies, or if I have overstated the science in any places. I want to be clear and confident, but I also don't want to overstep.

       My intent is to try to slow down the the climate "skeptics" momentum by raising some question marks about the authenticity of their claims.

        

       Shawn

       Moderator Response:

       [JH] I deleted a duplicate post of this comment.

41373. Composer99 at 23:20 PM on 17 October 2013
       Why trust climate models? It’s a matter of simple science
       

       Like any Earth science, climatology has the problem of not easily being able to run experiments the way one can in, say, particle physics or chemistry. As expensive as it is to build and run a particle accelerator, it is simply impossible to "build" an alternate Earth, more-or-less perfectly replicating the real thing, and run it through decades or centuries or millions of years of change in a reasonable timeframe.

       So you use a model.

       In essence, a computer model of the Earth climate system is a laboratory experiment of the Earth's climate. One you can run through in a reasonable amount of time, at a reasonable cost, and can replicate at will (subject to time/cost/other resource constraints).

       Yes, it's an approximation that will likely never be 100% accurate. But what matters is whether it's good enough to be getting on with, even as scientists work on developing better models and better understanding the Earth climate system.

       Of course, some of the components of the Earth climate are amenable to simpler forms of experiment, such as (to the best of my lay knowledge) analysis of the radiative properties of greenhouse gases. And, as noted by Kevn C, such analysis (as well as research into paleoclimate), rather than modeling, is what has led to our current understanding of climate.

       The bottom line is that our current understanding of the physics, of paleoclimate, and the current results of modeling, all are more than enough to be getting on with - particularly if what we are getting on with is coming to terms with the fact that we simply cannot continue to increase the concentration of long-lived greenhouse gases in the atmosphere if we want to avoid very unpleasant consequences.

41374. Dikran Marsupial at 20:53 PM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       In my opinion, SASM's responses to my questions demonstrate that he has no substantive point to make and is essentially just trolling.  His comments also show quite astonishing level of hubris and evidence of the Dunning-Kruger effect, so I susggest that we no longer indulge this sort of behaviour.

       Question 1:

       SASM wrote "only that we should not rely upon model projections as a basis of making policy decisions."

       So I asked "O.K., so if we are not going to use models that embody what we know of climate physics, specifically what should we use as the basis for policy decisions?"

       SASM replied "I believe we should use science, and models can be part of that. ..."  This is an evasive answer, which basically is a tacit admission that SASM has no suggestion of any alternative to the models (which are essentially a distillation of what we know about the science.  My question was designed to discover whether SASM actually had a substantive point to make, and it appears that he does not.

       SASM continues "I build models and pilots literally risk their lives on them (humbling thought to me), but we test the crap out of them."  This is an example of the hubris I mentioned, SASM assumes that the scientists have not "tested the crap out of them" and has not bothered to find out.  The models are tested in what are called "model intercomparison projects", with acronyms that end in "MIP".  There are dozens of them (of which CMIP3 and CMIP5 are merely the best known, there are also  AOMIP, ARMIP, AMIP, TransCom, CCMLP, C20C, C4MIP, DYNAMO, EMDI, EMICs, ENSIP, GABLS, GCSS, GRIPS, GLACE, GSWP, MMII, OCMIP, OMIP, PMIP, PILPS, PIRCS, RMIP, SMIP-2, SMIP-2/HFP, SIMIP, SnowMIP, SWING, SGMIP, STOIC etc (see McGuffie and Henderson-Sellers, "A Climate Modelling Primer", Wiley, table 6.5 for more details).  SASM is essentially indulging in boasting, suggesting that his field is superior to climate modelling, without actually bothering to find out what climate modelling involves.  This is a classic symptom of Dunning-Kruger syndrome.

       SASM continues "I explain fully the uncertainties we know about and when and where things are not accurate." Which is exactly what the climate modellers do, which is the point of running all the model intercomparison projects.

       SASM continues "I am not confident at all that current climate models are accurate." but cannot suggest any other approach, which is the point.  Sometimes decisions have to be made under uncertainty, and it would be irrational to ignore the best source of information we have on what is likely to ocurr in the future just because it isn't perfect.  As I said, SASM has no substantive point to make.

       Question 2

       SASM wrote: "They have not passed enough testing and verification for them to have that kind of power."

       So I asked "Please specify how much testing and verification would be required for you to accept their use as a basis for policy making."

       SASM replied "Wow, this is a hard question to answer. There is not a defined amount, but a range of testing." Again, SASM ducked the question.  The reason I asked the question was to see if there actually was some feasible test that would satisfy SASM's concern, or not.  His answer strongly suggests that no amount of testing that could be performed would satisfy SASM and that in fact it is just a way of avoiding accepting what the models say, no matter what.  In other words, just trolling with no scientific point to make.

       SASM continues "There is unit testing, and depending on the subsystem, it may get a lot more testing. ... This is where we go fly a test, measure a bunch of data, and then compare it to model predictions." This is just more posturing and hubris.  Climate modellers know about unit testing as well, and the also perform testing against observations, which is what all those MIPs are for.

       SASM continues "Validating climate models is hard because we cannot test against very accurate data sets for very long. Hindcasting isn’t accurate enough because the uncertainties of climate conditions are much larger than the CO2 signal."  Again, this is an indication that no test that could be performed will satisfy SASM, because the data will always not be accurate enough (for some unspecified reason).  The second sentence is also an unsupported assertion, that is at odds with what we currently know about climate variability (this is another example of hubris).

       Question 3

       I asked “Lastly, please explain why you have not mentioned the occasions where models have under-predicted the effects of climate change.”

       "I don’t think it matters -- wrong is wrong." Again an evasive answer.  It actually matters quite a lot.  If the models more frequently under-predicted the warming than over-predicted it, that would imply we should make greater efforts to mitigate against climate change.  The fact that SASM is apparently only interested in where the model over-predicts in combination with his previous comment "The concern I have about all of this is how policy developers and those with an agenda try to take the model results and over inflate them in an attempt to redirect the economy. That is big money, and if we’re going to spend a large part of the world’s GDP, we’d better be very certain of the reason." suggests that science is being used here as a smokescreen for economics/politics.  Evading the direct question is merely evidence to support this hypothesis.

       SASM made things worse by writing "Any model projection data in Tom’s chart prior to 1992 is a little suspect. I am certain that models did not correctly call the Mt Pinatubo eruption, so the projection dip in the early 1990’s has to have been a retro active adjustment to account for Mt Pinatubo."  This is astonishing hubris as it just shows that SASM has no real idea of how climate models work.  Volcanic activity is a forcing, i.e. it is an input to the model.  Observed forcings are used in making hindcasts, and the test is to see whether the model produces the correct response to the input.  In fact models were used to predict the effects of Pinatubo in advance as a test of the models.  It is ironic that you should be so certain of "retroactive adjustment", when you could easily have dound out with the slightest amount of checking your facts.  Instead SASM chooses to make some thinly veiled slurrs "This is a completely reasonable thing to do, but has anything else been done to make the models look better in the past? That is the good thing about the recent model projections – they are well recorded in IPCC documentation and the Internet, so trying to move the goal post is very hard."  implying that goal posts had been moved in the past.

       
       On Apophenia

       SASM wrote "Or that statistics has shown that what appears as a long term (100+ year) sine wave in the SOI really is not there?"

       
       You have normal scientific process exactly reversed there.  If someone wants to assert that there is a long term cycle there, the onus is on them to demonstrate that the observations are not explainable by random chance (under some suitable non-straw man null hypothesis).  That is the way statistical hypothesis testing works.  Of course occasionally papers get published (such as the Stadium Wave idea) and (while they may be interesting hypotheses) generally only use a straw man null-hypothesis, or don't actually perform a statistical test and generally have no plausible physical mechanism that can explain the size of the effect.  The litterature is full of such papers, and so far they have generally led nowhere.

       SASM wrote "My impression is that models assume ENSO, AMO, PDO average out to zero."  Again, more hubris, that ENSO/AMO/PDO may average out to zero in the long term may be a valid conclusion to draw fromthe models, it certainly isn't an assumption built into them.

41375. Kevin C at 19:52 PM on 17 October 2013
       Why trust climate models? It’s a matter of simple science
       

       Very good summary - thanks to Scott and Ars for allowing the reposting.
       

       However, given how easy it is to be distracted by rhetocial misdirections, I think it might be helpful to add one bit of context. The skeptic claim quoted at the start

       “That’s all based on models, and you can make a model say anything you want.”

       is false in both its first and second clauses. Our understanding of future climate is not all based on models. If we were to throw the models away as useless, we would still have a good idea of where we're going, because we can predict future climate on the basis of past climate over a whole range of timescales.
       

41376. panzerboy at 18:46 PM on 17 October 2013
       Two degrees: how we imagine climate change
       

       Alex Sen Gupta's comment on the conversation suggests the natural changes are "more likely 30x slower" than human. I particulary like

       "Exaggeration on either side of the fence is unacceptable. Please check your facts, its bad enough getting nonsense from the skeptics..."

       If only I could have said it so well.

       https://theconversation.com/two-degrees-how-we-imagine-climate-change-18035#comment_222606

41377. Tom Curtis at 16:28 PM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       60 Year cycle in the SOI?

       I think not:

       

       SASM, you should know better than to assert the existance of such a cycle based on just one "cycle" length of data, as in the inset of my graph @159, particularly given that the full series was displayed @69 of this discussion.  I note that even the appearance of a period in the data since 1975 comes almost entirely from the solid sequence of 5 El Nino's in succession in the early 1990's, and the concidence that over the last decade El Nino's (when occuring) have got successively weaker as the La Nina's have got successively stronger.  There may possibly be  reason for this as a response to forcing (although I know of no evidence to that effect).  There is certainly no reason to think that these two occurences, without precedent in the rest of the record, consist of part of a cyclical pattern.

41378. shoyemore at 16:04 PM on 17 October 2013
       Time to change how the IPCC reports?
       

       It seems incredible that we wil have to wait 6 years for the next IPCC Report, and this one is already out of date.

       Why not a shorter "State of the Global Climate" Report in 2 or 3 years? I agree that the emphasis should move to policy-based reports.

41379. panzerboy at 15:09 PM on 17 October 2013
       Two degrees: how we imagine climate change
       

       Chriskoz,

       Sorry that was a typo no offense intended.

       Moderator.

       I am a regular, daily reader of skeptical science. I'm a programmer not a scientist so I post rarely.

       I am genually confused by the statements that events of the last ice age happened 18,000 years ago over a timeframe of 'hundreds of years'. That Ice age was 2 degrees celsius different?

       Why shouln't I conclude that the author meant 10,000 times the rate of those 'hundreds of years', I don't see how to read that any differently.

       I'm sure a denier would have much fun with this arithmetic. The admittedly clumsy accusation of alarmism was intended to highlight what I think is a gift of ammunition to the deniers.

       I think I get it, climate may cool down into ice ages fast, 'hundreds of years'.

       But they recover slowly? Over thousands of years.

       The following from wikipedia suggests the opposite. The recover in a few thousand years but slide into ice ages over 1 hundred thousand years.

       http://upload.wikimedia.org/wikipedia/commons/b/b8/Vostok_Petit_data.svg

       So ten thousand times the rate of ? four thousand years is still a little under 5 months.

       Perhaps someone could point out where this 10,000 times rate comes from, or the error in my arithmetic?

        

       Jeremy Thomson

       (I'm no troll, thats my real name I just prefer to post in blogs using the panzerboy account name)

       Moderator Response:

       [JH] Thank you for the clarification. Please take the time to carefully review your draft comments before posting them. 

41380. StealthAircraftSoftwareModeler at 14:20 PM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       I’m trying to answer all the questions. I thought I had indirectly answered them but it appears not. So, here are explicit answers to questions in reverse order of posting.

        

       Tom Curtis @177: Yes, I agree with your statement that short baselines are not fair in determining whether or not climate models fail or not. However, I do not think I was doing that. I only tried to reproduce the draft chart (left chart) with original source data, and I did that. You don’t think 1990 is a good start because that is only 23 years ago and we need at least 30 years. Okay, I can accept that. I’d reference Spencer’s chart here, but there is no need, other than to say “shame on him” for using a fake Time cover. You *can* expect more from me, I promise. But I do not like trend lines because if they are long then it takes a long time to detect a change. As an example, I could fit a line to the last 100 years of data, and even if temps plunged back down to -0.5C, it would take a long time for the trend line to change. Please give me the return courtesy of acknowledging that point.

       Dikran @ 175: I read some links on SkS when I searched “climastrology” and none applied to my observation. I believe you mean Apophenia (http://en.wikipedia.org/wiki/Apophenia), which is seeing things in random data. I’m familiar with it -- children seeing animals in clouds is a classic example. Are you asserting that I am “seeing things” and that SOI oscillations are short term and there are no multi-decadal oscillations? Or that statistics has shown that what appears as a long term (100+ year) sine wave in the SOI really is not there? I’d like to see those results. Wyatt’s and Curry’s Stadium Wave paper (I’ve posted links or you can Google it) talks exactly to the issue that there *are* long oscillations in the AMO and PDO. How do climate models represent these major and oscillating climate drivers? My impression is that models assume ENSO, AMO, PDO average out to zero. Which could be an enormous source of error, and it wouldn’t show up in hindcasting, but it would show up when the large oscillation changes phase, like the last decade. In examining Tom’s SOI chart @159, it is clear that SOI peaked in 1983 and 1998, and since 1998 it has been plunging. And most of the SOI was pretty high from 1975 to early 2000, which is where all of the warming has occurred since 1950. Could be something, or it could be apophenia again.

       Dikran @166: The specific questions you want answered:

       “O.K., so if we are not going to use models that embody what we know of climate physics, specifically what should we use as the basis for policy decisions?” I believe we should use science, and models can be part of that. I build models and pilots literally risk their lives on them (humbling thought to me), but we test the crap out of them. I explain fully the uncertainties we know about and when and where things are not accurate.I am not confident at all that current climate models are accurate.

       “Please specify how much testing and verification would be required for you to accept their use as a basis for policy making.” Wow, this is a hard question to answer. There is not a defined amount, but a range of testing. There is unit testing, and depending on the subsystem, it may get a lot more testing. Most tests are designed to confirm requirements are met, so those types of tests a well defined. The hard tests are to match modeling with measurements. This is where we go fly a test, measure a bunch of data, and then compare it to model predictions. Trying to figure out differences can be very hard. Is it the model, was it random noisy world effects, was the test instrumentation calibrated, and so on. Validation testing of a model is more of an evolving process based on the model than a check list. Validating climate models is hard because we cannot test against very accurate data sets for very long. Hindcasting isn’t accurate enough because the uncertainties of climate conditions are much larger than the CO2 signal.

       “Lastly, please explain why you have not mentioned the occasions where models have under-predicted the effects of climate change.” I don’t think it matters -- wrong is wrong. Any model projection data in Tom’s chart prior to 1992 is a little suspect. I am certain that models did not correctly call the Mt Pinatubo eruption, so the projection dip in the early 1990’s has to have been a retro active adjustment to account for Mt Pinatubo. This is a completely reasonable thing to do, but has anything else been done to make the models look better in the past? That is the good thing about the recent model projections – they are well recorded in IPCC documentation and the Internet, so trying to move the goal post is very hard.

       Moderator Response:

       [Rob P] - a portion of this reply addressing a 'dogpiling' comment has been deleted

41381. chriskoz at 12:03 PM on 17 October 2013
       Time to change how the IPCC reports?
       

       Tom@1,

       Some aspects of Kevin's suggestion are reasonable and should not be portaryed as "a concession of defeat in its (IPCC) current mission". BTW, deniers are and will be trying to downplay/denigrade inconvenient science no matter how presented.

       For example, here:

       It no longer makes sense for the activities of Working Group 1 (which assesses the physical scientific aspects of the climate system and climate change) and those of Working Group 2 (which looks at impacts, adaptation and options for coping with climate change) to be separated

       I tend to agree. There might be no point in analysing certain aspecte of climate science over and over because it's settle science. I think no one disputes that human CO2 emissons are causing warming (except lunatics), even policy makers-deniers like Tony Abbott acceptsa that, so WG1 report should be scaled down. However, the same Abbott denies that CTax/ETS is the effective market way to tackle the emission, so WG2/3 reports should be scaled up as they are needed now more than ever.

41382. scaddenp at 11:43 AM on 17 October 2013
       Arctic sea ice has recovered
       

       ...and US government shutdown is making data they need unavailable delaying the run.

41383. scaddenp at 11:41 AM on 17 October 2013
       Arctic sea ice has recovered
       

       William, ice volume is not measured directly but calculated via the PIOMAS model. This is done monthly. You can get details here

41384. william5331 at 11:33 AM on 17 October 2013
       Arctic sea ice has recovered
       

       What I would like to know is why the ESA is not publishing a constantly updated graph of ice volume from cryosat as NSIDC does on ice extent.  The weather patterns we have had in the summer of 2013 have a tendency to spread ice out (coriolis) and anything over 15% ice cover is recorded by NSIDC as full coverage.  The increase in ice extent may be an reading glitch, at least to some extent.  The ice volume results should clear up by how much the ice has actually increased between the middle of Sept 2012 and 2013 but the ESA seems oddly reluctant to tell us what their results are.

41385. vrooomie at 08:47 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM, per Tom Curtis's post nu. 177, I, too, am not pursuing other questionable statements you have made until such time as you have answered his, and other's, questions.

41386. nhthinker at 08:15 AM on 17 October 2013
       Understanding the pre-IPCC Anti-Climate Science Misinformation Blitz
       

       My claim#32: "Annual Global Mean Surface temperature is the only metric that the general media actually reports that scientists use to measure the impacts of the the enhanced greenhouse effect on the Earth's climate system."

       grindupBaker #42: "So it is patently absurd to say that "global warming" is only an increase in atmospheric heat content and when I find that climate scientist you say told IPCC to say that I'll chastize him/her severely."

       Show me a single media report that puts a number range on the predicted mean ocean temperature rise in the next 100 years due to global warming as it does for atmospheric temperatures.  I have not seen one.  Googling it doesn't show one either.  So if you have data that conflicts with my claim/assertion, please provide it.

41387. Tom Curtis at 06:38 AM on 17 October 2013
       Time to change how the IPCC reports?
       

       With the greatest respect for Kevin Trenberth, I disagree.  The IPCC provides an impartial, conservative benchmark on the state of climate science.  As a consequence, its reports have a substantial impact in convincing the general society of the reality, and danger of climate change.  It is for that reason the denier movement expends so much energy in attacking the IPCC.  If the IPCC substantially changes its mission, that will be portrayed by deniers as a concession of defeat in its current mission, a portrayal that will resonate with the public.  Therefore such a move would be a backward step in attempts to get global policy settings that will adequately tackle climate change.

41388. Tom Curtis at 06:29 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM @170, my post @169 ended with a very clear statement:

       "I expect you to at least acknowledge that the use of short baselines is bad practise, and should not be done for purposes of illustration nor in attempting to establish whether or not the observations have fallen outside the predicted range."

       
       Absent such an acknowledgement by you, there is no point in pursuing more complex issues with regards to models than their ability to predict GMST.  If you cannot bring yourself to acknowledge very basic standards of practise when it comes to testing predictions, complicating the topic, in addition to being off topic in this thread (IMO) will simply multiply the opportunity for evasion.  Indeed, evasion appears to me to be the purpose of your post @170.

       Consequently, absent a clear acknowledgement by you of the inappropriateness of short baselines in model/observation comparisons, or a clear and cogent defence of the practise despite the twin disadvantages of eraticness and overstating of differnces in behaviour based on differences in variability, there is no point if further pursuing this (or any) topic with you.

       I ask that other posters likewise decline to participate in your distractions until we have a clear statement by you on this point.

       Moderator Response:

       [JH] You have read my mind. I encourage your fellow commenters to follow your recommendation. 

41389. Dikran Marsupial at 05:21 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM wrote "You guys see that?"

       The human eye is very good at seeing spurious patterns in noisy data, which is why scientists use statistics, if only as a sanity check.  There are plenty of articles on SkS that deal with "climastrology", I suggest you read some of them before continuing this line of reasoning, you will find it is nothing new and not well founded.

41390. Dikran Marsupial at 03:43 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM If there was a serious inconsistency between the models and observations since 1950 (!) the skeptics might just have pointed it out by now, for that matter the modellers themselves might just have noticed and done something about it.   Where there actually is a serious inconsistency (e.g. Arctic sea ice), the modellers are generally very happy to discuss it, that is what they do for a living.

       Please could you clarify your position by answering the questions I asked earlier (at least the first two).

41391. william5331 at 03:36 AM on 17 October 2013
       2013 SkS Weekly News Roundup #42A
       

       Can't remember where I saw the article but some work on stalegtites suggested that Aus has a 200 year cycle of drought and wet.  The article suggested she has just ended a wet period!!!!??.  If the past few decades were wet what must the dry look like.  Add in climate change and I think I would immigrate to somewhere else.

41392. StealthAircraftSoftwareModeler at 03:34 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       I didn’t think 63 years – from 1950 until today – was short term at all. Perhaps it is, or we’re miscommunicating. I’d like to see model projections for air temp, sea temp, humidity, cloud cover, and precipitation, just as it has been shown for only air temperature. Take the IPCC’s chart, or better yet, Tom Curtis’ chart @159 and so me the model projections for air temp, sea temp, humidity, cloud cover, and precipitation. Is that an unreasonable request or do you think it will have meaningless implications?

       Moderator Response:

       [JH] Your requests for the forecasts of the indicators that you have listed should be directed to the organizations who actually develop and maintain the GCMs. Please let us know if you need contact information for these organizations.

41393. StealthAircraftSoftwareModeler at 01:45 AM on 17 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Tom Curtis @168: “this illustrates the absurdity of SASM's approach of testing models against just one value”, you know, I had this very thought last night, and I agree with you totally.

       The model ensembles show air temperature, but as this site has pointed out (presumably correctly), on the order of 90% of the energy goes into the oceans. Due to this, air temperature is almost irrelevant to the system. So, what would be a meaningful and informative test of climate models? How far back to look and what to examine or measure?

       I do not think the models can properly represent the various components of the earth’s energy budget, all of which combine to produce an average air temperature. Air temperature is what everyone worries about the most, but that is just 1/3000th of the heat capacity of the earth, by volume. Since air is mostly warmed indirectly, it is important to correctly model the things that heat the air. In order for me to have a sliver of confidence in a climate model, I’d want to see that a model can reasonably** project changes in the energy budget, say: air temp, sea temp, humidity, cloud cover, and precipitation. If you have opinions about other or different drivers, then I’d like to hear about them.

       I think these are the major components to the energy budget, and I’m only looking for global averages. I am not expecting climate models to able to predict when it will rain at some location. If climate scientists and modelers have a good handle on climate physics, then they should be able to do a reasonable** job at projecting the annual global average of these values. Let’s start from 1950, which is where the IPCC says our AGW effects start. Can anyone plot the model average and +/- 2.5%ile bounds for these values along with actual measured data? Or, can someone point me to a paper to covering this? I’d be stunned if someone has not already done this analysis.

       **reasonable: let’s define “reasonable” as getting the trend direction correct. If a model projects one of these components to go up over the last 63 years, but it goes down, then the model is wrong for that component. If the model is wrong on several components, then how can anyone conclude they are correctly modeling the climate?

41394. Synapsid at 00:35 AM on 17 October 2013
       2013 SkS Weekly News Roundup #42A
       

       numerobis:

       Pipelines are necessary to increase production if you listen to CEOs; there's money in pipelines.  It's much faster to expand shipping by rail, though, than it is to build a pipeline; cheaper too, and rail allows great flexibility in supplying markets.  Both are being used, and it's rapid growth in rail transport that is allowing rapid increase in export from Canada.  Sideshow?  I said that Keystone XL is a sideshow compared to coal, not that pipelines are a sideshow.

       Nor did I say oil is less important to stop than coal is.  Coal has much greater potential for future harm than oil has but, at least if you consider informing the public important, it gets far less attention than Keystone XL does and that imbalance should be fixed.

41395. funglestrumpet at 00:32 AM on 17 October 2013
       2013 SkS Weekly News Roundup #42A
       

       The  link to the Coming Plague article appears to be broken, or my computer is having another one of its funny turns.

       Moderator Response:

       [JH] The link has been fixed. Thank you for bringing this glitch to our attention.

41396. numerobis at 23:52 PM on 16 October 2013
       2013 SkS Weekly News Roundup #42A
       

       "In 2012 Canada exported more oil, crude plus concentrate in industry terms, than in any previous year; the total for 2013 will be higher" -- how does this make it *less* important to stop?

       You seem to have bought the oil company claim that the pipelines are a sideshow; without pipelines, they'll just ship it by train.  This is their message to those who want to limit production.  They have another message to those who want to maximize short-term $$$, which is that the pipelines are absolutely crucial to increase production.

       Moderator Response:

       [JH] To whom is your comment directed? 

41397. Leto at 21:44 PM on 16 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Thanks Tom@168.
       I was aware of Kosaka and Xie. Their approach is interesting, but potentially open to the charge (by motivated parties) that the close match they demonstrated merely reflects that the model was constrained by reality, and hence matched reality. (The model was not actually tightly constrained, but we all know contrarians have run with weaker material.)

       I was hoping that a few unconstrained model runs had chanced upon an ENSO profile similar to reality. For instance, if all model runs in the ensemble were ranked according to their mean squared SOI error with respect to the historical SOI, I would expect that the best-matched quartile (top 25% of runs in the ranking) would match reality more closely than other quartiles. After all, the models' developers never claimed to be able to predict ENSO conditions, so it would be nice to minimise the effects of ENSO mismatch. This would support the notion that the minor, statistically insignificant divergence between the ensemble mean and observational record (over some timeframes) is largely due to an el nino in 1998 followed by la nina and neutral conditions for many of the following years. It is a shame if this type of data is not available in the public domain.

       Of course, if the science were being conducted in an ideologically neutral environment, such an obvious issue would not draw so much attention in the first place, and I would not propose such an analysis. For me, the Nielsen-Gammon plot, mentioned in several threads here at SkS, says it all.

41398. Tom Curtis at 21:03 PM on 16 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       Leto @162, I am not sure that that can usefully be done.  However, Kosaka and Xie have gone one better.  They took a model, constrained the tropical pacific temperature values to historical values to force it to adopt the historical ENSO record, and compared that to observations:

        

       Tamino's discussion (from which I draw the graph) is very informative.

       To bring that back to the discussion on hand, I checked the 1990-2012 temperature trend of that model when run with the CMIP3 experiment.  It was 0.317 C/decade.  That puts it at the 80.8th percentile, and definitely one of the fastest warming models.  Yet when constrained to historical ENSO fluctuations, it almost exactly matches the HadCRUT4 record.

       This, I think, illustrates the absurdity of SASM's approach of testing models against just one value, and if they almost (but not quite) fail the test, rejecting them as completely irrelevant as a basis of information.

41399. Tom Curtis at 20:35 PM on 16 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM @165, unfortunately, I do not think you understand my position.  In particular, I was not criticizing your choice of baseline on the basis that it makes the observations look cool.  On the contrary, a 1990 baseline makes the observations look warm. The emphasis on that point is so that my allies pick up on the fact.  Intuitively, we would expect a 1990 baseline to cause the observations to look cool, for 1990 is a local high point in the observations.  However, that is not the case, for though the observations are warm, the ensemble mean is warmer still relative to adjacent years.  Thus, if anything, a 1990 baseline is favourable to a defence of the validity of models.

       But it is still wrong.

       It is wrong, basically, because you have to analyze the data as you motivated me to do to know whether it is favourable, unfavourable or neutral with regard to any position.  The only way to avoid that necessity is to use a long (thirty year) baseline so that the baseline is robust with respect to time period used.  Ideally, we should use the long baseline that minimizes the Root Mean Squared Error (RMSE) between the observation and the ensemble mean.  By doing so, we ensure that any discrepancy between observations and ensemble are real, ie, are not artifacts of an ill chosen baseline.

       The impact of short baselines is shown by KR's graph @164.  The UAH temperature record is far more sensitive to ENSO fluctations than any surface record.  As a result, the inclusion of the strong El Nino of 1983 in a short baseline period artificially displaces the UAH record downwards with respect to HadCRUT4 (and both HadCRUT4 and UAH downward with respect to the ensemble mean).

       The crux is this: Spencer (and you and McIntyre) have created graphs to illustrate the relationship between observations and models.  Yet all of you have adopted non-standard conventions, the effect of which is to show a greater disparity than actually exists.  This is achieved by three different methods in the three cases (and I have only discussed Spencer's method so far), but is the case none-the-less.  Now, to the extent that you intend an honest comparison, you would avoid any method that might accidentally result in showing a greater disparity (if that is what you are trying to demonstrate).  Short term baselining is a method that will have that effect.  When it is adopted to compare data with known large differences in variance (as, for example, HadCRUT4 and UAH) it is scientific malpractice.  It is, not to put to fine a point on it, the sort of thing I would expect from a person who uses a known faked Time magazine cover to establish a rhetorical point, and who refuses to take it down, issue a correction or acknowledge the fault when corrected by others.

       I expect better of you than of Spencer.  I expect you to at least acknowledge that the use of short baselines is bad practise, and should not be done for purposes of illustration nor in attempting to establish whether or not the observations have fallen outside the predicted range.

41400. Dikran Marsupial at 17:11 PM on 16 October 2013
       Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
       

       SASM wrote "only that we should not rely upon model projections as a basis of making policy decisions."

       O.K., so if we are not going to use models that embody what we know of climate physics, specifically what should we use as the basis for policy decisions? 

       "They have not passed enough testing and verification for them to have that kind of power."

       Please specify how much testing and verification would be required for you to accept their use as a basis for policy making.

       Lastly, please explain why you have not mentioned the occasions where models have under-predicted the effects of climate change.

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