Are Climate Models Falsifiable?

From Maurizio Morabito:

The issue of model falsifiability has already been a topic on the NYT’s “Tierney Lab”, daring to ask this past January questions such as “Are there any indicators in the next 1, 5 or 10 years that would be inconsistent with the consensus view on climate change?” and “Are there any sorts of weather trends or events that would be inconsistent [with global warming}?“.

And what did Gavin Schmidt reply on RealClimate? No, and no:

this subject appears to have been raised from the expectation that some short term weather event over the next few years will definitively prove that either anthropogenic global warming is a problem or it isn’t. As the above discussion should have made clear this is not the right question to ask. Instead, the question should be, are there analyses that will be made over the next few years that will improve the evaluation of climate models?

No “short-term weather event over the next few years” could ever disprove that “anthropogenic global warming“. And observations (events) and their analyses, in the RealClimate world, are only interesting to “improve the models“.

Convinient.  Convinient, that is, if you are after a particular answer rather than the correct answer.

30 thoughts on “Are Climate Models Falsifiable?”

  1. Is it really so hard to understand that climate is inherently a long term phenomenon and that weather variation dominates over timescales shorter than at least a decade? If you are dogmatic and stupid, then I suppose it must be hard to understand this.

  2. Well when you have some scientists telling the world we have till 2010 to the point of no return or that by 2050 we will be in the middle of a disaster, watching as the water gradually rises above our heads, drowning us in slow motion, you start to wonder where weather ends and climate begins. I guess it all depends on what you define as “long term”. 50 years is a blip in time in terms of geologic timescales. You could just as well argue that the warming up period of the 70’s, 80’s and 90’s was also just “weather” variation and not some CLIMATE change. Now that there has been no warming for ten years, it is only just weather; but had it been warming since 1998, it certainly would be attached to the previous AGW interpretation. Strange how the AGW people get to define every one of their variables when it suits them. When data that seems to even slightly call into question their models, they change the game once again and just become more convinced in their own interpretation. Notice, not even an inkling of doubt or self-reflection in their views. And still they use ad-hominem attacks on those who have focused on the lack of correlation between the models and actual data.

  3. You could just as well argue that the warming up period of the 70’s, 80’s and 90’s was also just “weather” – no you couldn’t. Please check up on the definitions of ‘weather’ and ‘climate’.

    Now that there has been no warming for ten years – ah, the unmistakeable sign of an idiot. Warming continues.

  4. It would be interesting if “Scientist” would come up with ways to falsify the climate models, since as we know the people at RealClimate won’t. The “warming vs. climate” picture confirms my point: as long as there is _any amount_ of “warming”, the climate models will be considered _right_ (in the sense of “not false”).

    One can imagine a period of 20 years of cooling dismissed out of hand as “aerosols” or “soot” or whatever else: with the climate models still “right”, no matter what.

    On the other hand when, say, James Hansen talks about “tipping points” he is not referring to changes that will be visible only after 10 or more years of statistics: rather, to spectacular modifications of the world as we experience it. Am I mistaken on this point?

    So please, if you can, try to be explicit about what observations would make you change your mind.

    As I mention in my Moon Hoax blog, the difference between a dogmatic and a honest debater is that the former invariably never ever reveals what evidence would convince them to change their mind.

  5. Scientist: you must answer one question: Who is the idiot, the person posing an inquiry or the other person calling names? Maybe not a true idiot, but someone who has the emotional maturity of a 7 year old. Just in case you didn’t get my inquiry? How do you know that 30 years is enough to be called “Climate” and 10 years is “weather”? I guess it’s in the text books of experts in the field. Perhaps the experts are wrong. Don’t be threatened by an inquiry. Try some cookies and milk for comfort.

  6. mbabbitt – the claim that ‘warming stopped in 1998’ is a stupid one. It’s trivial to show that it’s not true. The only people who make this claim are the most data-illiterate deniers. I feel quite comfortable in saying that anyone who trots this saw out is an idiot.

    “Maurizio Morabito” – dismissed out of hand as “aerosols” or “soot”… what a bizarre comment. These scientists eh! See a UFO and they dismiss it out of hand as “a plane” or “Venus”. Notice that the sky is light long after sunset and they’ll dismiss it out of hand as “twilight”.

    The real question is, why do you not believe all the extensive evidence we have that anthropogenic global warming is real? And why, when pretty much everyone here is so web-illiterate that they can’t even manage to make hyperlinks, do they think they are scientifically literate enough to even discuss climate issues, let alone think that they know the truth and the professionals are wrong?

  7. Deary deary me. We did the climate-vs-weather one and the has-warming-stopped ones before, in great detail, and you lost. Badly. Now you want to bring it up again?

    To repeat – the temperature has recently gone down, (although the trend is not significantly different from zero and it doesn’t tell us anything about AGW either way). What you are saying is that if you take that temperature record, extend it into the past to include an interval of warming, smooth/average it to hide the autocorrelation structure, and fit a least-squares linear trend to the result, then the trend line still goes up. Your claim is false simply because you have tried to argue against one variable going down by pointing out that another entirely different variable does not. But you have also failed to note that the autocorrelation and non-Normality of the distribution invalidate the LS-statistic, that there is no scientific support for your statistical model of linear trend plus iid Normal errors on which your curve fitting exercise depends.

    There is also no evidence that ‘weather’ does not extend to multi-decadal timescales. The PDO, AMO, etc. cycles demonstrate that. You have provided no reason to doubt it, other than quoting the definitions used by various ‘authorities’.

    “why do you not believe all the extensive evidence we have that anthropogenic global warming is real?” Because nobody can show us any. Nobody seems to know what it is. There’s just a lot of political activists asserting that there’s “lots”. It doesn’t take a PhD in the philosophy of the scientific method to know that there’s something iffy about that.

  8. ” Because nobody can show us any [evidence]. Nobody seems to know what it is. There’s just a lot of political activists asserting that there’s ‘lots’. It doesn’t take a PhD in the philosophy of the scientific method to know that there’s something iffy about that.”

    I agree 100%. As Karl Popper observed, “Confirmations should count only if they are the result of risky predictions . . . .”

    For example, is a collapsing ice shelf evidence of global warming? You need to first ask the opposite question — what if the ice shelf had NOT collapsed? Would that be evidence against global warming? If the answer to the second question is “no,” then the answer to the first question is also “no.”

  9. Who’s this “Scientist” person anyway and why does he or she feel so compelled to show lack of arguments, substituted by rather dis-useful insults?

    For my part, I will believe in climate change when I will see compelling evidence of changes in the climate. Like different prevailing winds, or a sustained Southern Atlantic hurricane season, or whatever else of the sort. It’s unfortunate that no AGW climatologist is interested in any of that.

    As for dismissing any cooling as due to some additional “forcings”, it has to be taken quite literally. All you have to do is tweak the model, and voila, magically everything will fall back into AGW line. Given enough parameters, it is well known, anything can be modeled.

  10. So, “Maurizio Morabito”, how do a surface warming of 0.2°C per decade, a cooling stratosphere, increasing hurricane strength, 99% of non-polar glaciers receding, Arctic ice thinning and its coverage shrinking, and sea levels rising not count as compelling evidence of changes in the climate?

  11. Let’s assume all the stuff you’ve listed is actually happening (not sure about non-polar glaciers, for example…is “99%” an actual value or just figure of speech? Hurricanes, too, may appear as increasing in strength, but so do earthquakes: a matter of better instrumentation, not of intrinsic “change”).

    Well, there is enough evidence of what you’ve listed and its opposite as having happened in the XX century alone. Balmy Arctic summers in the 1930’s and the likes. Why shouldn’t we take those as natural climate variations, I do not understand.

    Anyway…your list is out of touch with RealClimate. Remember: no single event, and no set of short-term events, can disprove (or prove) anthropogenic climate change. That includes, decadal surface warming, cooling stratosphere, increasing hurricane strength, the behaviour of non-polar glaciers, what happens in the Arctic, and rising sea levels.

    You’re still saying nothing on what would make you change your mind. Don’t worry, take your time.

  12. Maurizio,

    You noticed that (not so) subtle shift from “anthropogenic global warming” to just “changes in the climate” too, then?

  13. “Maurizio Morabito” – no, earthquakes do not appear to be increasing in strength. Where did you get that preposterous notion from? For hurricanes, read papers by Kerry Emmanuel. For glaciers, check up the World Glacier Monitoring Service. Your third paragraph is a pathetic misunderstanding.

    Stevo – your post above is seriously the most idiotic thing I’ve seen on this blog, even though it competes with a very large number of idiotic things. No-one seems to know what the evidence is for anthropogenic global warming? You obviously don’t. Pull your fingers out of your ears and do some research instead of coming out with cretinous bullshit like that. I just listed some evidence above. The temperature recently has not gone down, no matter how much the weak-minded desperately wish it had done. Rabbiting on about autocorrelation and other irrelevances won’t change that.

    If you wish to keep on demonstrating facile ignorance, that’s your choice. I find it hilarious that you think you have won any arguments with me. You haven’t, you really really haven’t. No facts support your views. I know you’ll never believe that because you’re too mentally deficient to comprehend all of this, but there you go. I really hope you have something of worth in your life beyond being publicly ignorant about climate change because your posts here are utterly valueless.

  14. You have listed NO evidence for anthropogenic global warming. You have instead listed evidence for global warming. You’re failure to understand the distinction is a large part of your problem.

  15. Scientist: Why do you hang out at this web site if they make you so angry? You seem a very angry person. Disagreeing with someone is one thing. Being filled with vitriol is another. Are you this angry in your real life or is this a persona you adopt on the web where you can hide yourself — like when driving in traffic?

  16. Stevo. even the liar who writes this blog doesn’t dispute that CO2 is a greenhouse gas. The increase of its concentration by 40% over 150 years is the main cause of the observations I listed. Non-anthropogenic factors alone cannot account for the warming we’ve seen. This is very basic stuff.

  17. I don’t dispute that CO2 is a greenhouse gas either, and never have. But your other statements don’t logically follow from it. The first is an assertion with no reason given but which appears to be either correlation implying causation or affirming the consequent. The second is an argument from ignorance and false dichotomy – that because we don’t know how to account for the rise without anthropogenic factors, concluding that such an accounting is impossible.

    Since a similar level of warming occurred during the MWP and the Holocene optimum, it quite clearly is within the range of natural variation, and what with the relationship of the 30s warming (before the bulk of CO2 emissions), 60s cooling, and 80s warming being so closely related to the phases of the Pacific Decadal Oscillation for example, which computer models are currently unable to reproduce incidentally, I don’t think we can say we’ve eliminated all the alternatives.

    The trouble is, the very basic stuff is wrong. The AGW argument, if there is one, is much more complicated than that. As we’ve noted before, CO2 can’t account for the warming we’ve seen either unless you introduce a large feedback to amplify it, for which the physical evidence is dubious. Because that is an element of the climate system we don’t understand, it’s not impossible that there is such a feedback, but we simply don’t have any evidence for that.
    But it is an entirely different question as to whether CO2 is a greenhouse gas. It is. So what? It doesn’t prove what you seem to think it proves.

    The AGW argument in detail is sophisticated and subtle – it is not of a “CO2 is a greenhouse gas that warms the surface” simplicity. It has lots of components that interact in complex ways and involves a lot of quite difficult physics. When we sceptics criticise the primary school version of “CO2 is a greenhouse gas” as being unable to account simultaneously for the observed and predicted amounts of warming, we quickly (and quite rightly) get told that this isn’t what climatologists say at all. Both I and the blog owner acknowledge that too – it seems very strange that you don’t.

    In the troposphere there are three principle radiative effects – shortwave absorption by H2O, and longwave radiative transfer by both H2O and CO2. The sunlight absorbed by water vapour warms the air, nearly balancing the cooling of the air to space due to longwave emission from CO2. The effects virtually cancel. The bulk of the radiative cooling is due to the longwave emitted by H2O. The overall rate is controlled by the temperature of the gas at the level where it radiates to space – i.e. about one unit of optical depth from the top, although obviously there is a range. Since a greater partial pressure of CO2 or H2O raises this level, and since below the tropopause the temperature drops with altitude, more greenhouse gases cause a cooling of the air radiating to space and hence an overall warming of the whole system. If the unit optical depth was at or above the tropopause, there would be no change in temperature and most of the effect would cancel out.

    The radiative ‘blocking’ of heat in a thicker atmosphere can in some circumstances be a real effect, but in the case of Earth’s atmosphere is too simplistic an explanation. You can easily calculate the effect in a static opaque atmosphere to give T=((N+1)(1-A)F/sigma)^1/4 where N is the optical depth, A the albedo, F the solar heat flux at the top of the atmosphere, and sigma the Stefan Boltzmann constant, and since optical depth is approximately an exponential function of altitude for a well mixed gas (note, this does not apply in the same way to water vapour), the efficiency with which radiative balance can cool the planet decreases rapidly as the air gets denser. Once the temperature gradient falls below the (moist) adiabatic lapse rate, turbulent convection and the evaporation/condensation cycle takes over as the dominant heat fluxes. Below this level, the tropopause, this opaque atmosphere version of the greenhouse effect does not work. (And as I hope everyone knows, real greenhouses work by stopping this convection.)

    And that’s before you even start on the complexity of having different lapse rates, humidities, and tropopause heights in different parts of the globe.

    Actually calculating whether and by how much an increase in CO2 will cause warming is an extremely sophisticated calculation involving the effects of Doppler broadening of absorption lines, the different optical depths and hence emission altitudes of the different gases, the changing temperatures at those altitudes, in an extremely complicated non-linear system of simultaneous differential equations. It’s so complex, that even with modern computers they have to simplify it by only doing it in one dimension, and in other ways. The scientists doing it are very clever, but they’re not infallible.

    This is absolutely NOT “very basic stuff”.

    This is also the sort of stuff that I was waiting for you as a ‘climatologically expert scientist’ to be telling us as ‘scientifically ignorant sceptics’, the sort of depth and detail that I would expect from a genuine scientist who wanted to educate us. Why do I find that I have to be telling you?

    But I would like to take the opportunity to congratulate you on almost providing an evidence-based argument. “Non-anthropogenic factors alone cannot account for the warming we’ve seen” does at least vaguely indicate a reason for you believing it, even if it’s wrong. Perhaps if you work on that part, fill in the rest of the logic, maybe we could get somewhere more positive than name calling.

  18. You think people here are ready for the complex stuff? Most of you are still wallowing in ‘not even wrong’ territory. You miss basic points. Your approach is selective and defective.

    it quite clearly is within the range of natural variation – yes, and if it reached 20°C at the north pole, that’s happened before so that would also be within the range of natural variations. So what? Equating ‘within the range of natural variations’ with ‘not caused by humanity’ is a fallacy.

    80s warming being so closely related to the phases of the Pacific Decadal Oscillation for example – yeah, but that doesn’t work, does it, because the past decade has been the hottest in the record, and is far hotter than pre-1940s temperatures. The current PDO index is lower than that seen in 1940, and yet temperatures are 0.5°C hotter. Checking the data is a basic first step to assess whether your arguments will stand up.

    it’s not impossible that there is such a feedback, but we simply don’t have any evidence for that. – yes, yes we do. The ice-albedo feedback clearly is operating. CO2 as a feedback accelerates the warming at the ends of ice ages. Again, you seem perversely happy to blinker yourself by not reading around the subject.

    they have to simplify it by only doing it in one dimension – no they don’t. 3D radiative transfer codes are used.

    Why don’t you educate yourself on the current state of research, instead of simply deciding what you believe about it and sticking to that view regardless? And if you don’t like name-calling, you should probably not call people names.

  19. “Equating ‘within the range of natural variations’ with ‘not caused by humanity’ is a fallacy.”

    Strawman. I haven’t equated the two. My argument is that the potential for natural variations to cause similar scale warming falsifies the claim that such warming cannot occur without anthropogenic input. I haven’t said that it implies the warming cannot be anthropogenic.

    Your check on the PDO correlation is much better. (Actually, you do get a better correlation if you compare the rate of change of temperature with PDO, but certainly the match is not perfect.)
    Yes, I agree, the PDO on its own cannot explain the entire change. You also have to add in the AMO and ENSO. There’s also the solar-cloud connection accounting for about 30% of the warming according to some researchers. There is also always the potential for other contributors we don’t know about. And yes, there would be expected to be a few tenths of a degree from CO2.

    I’m certainly glad to hear they’ve started using 3D radiation codes now. Last I heard,, they used 3D models to generate parameterisations for the 1D models they used in GCMs, which was itself a new development only within about the last five years. My information must be out of date. If you gave a reference like you did on the PDO one, that would have been jolly helpful, but I suppose I can’t expect too much.

    Apart from the first and last paragraph, that was almost civilised. As for calling people names, it’s strange that it doesn’t happen with anyone else but you. Everyone else seems to get along fine. Is there some connection, do you think?

  20. Now why do people call me names? Because I am the only person around who is pointing out the massive errors and flaws in their thinking? Yes, I think that’s it.

    falsifies the claim that such warming cannot occur without anthropogenic input – strawman yourself. ‘Such’ warming can occur naturally. We understand this. This warming cannot be natural.

    You think oceanic oscillations explain it all, do you? Please give us links to the work on that.

    according to some researchers – and who might they be?

    they used 3D models to generate parameterisations for the 1D models they used in GCMs – again, simple, basic misunderstandings. You just don’t understand where things are at. Try reading something basic, and try to learn rather than just assuming.

    Apart from the first and last paragraph, that was almost civilised – you’re a complete fucking twat, Stevo.

  21. I think the last bit gives everyone the clearest insight into the character of AGW supporters faced with disagreement. Congratulations. You’re making people really not want to be like you. But I really wish you wouldn’t. It’s not considerate to use that sort of language on somebody else’s public blog that children could access.
    And it doesn’t work anyway. Nobody believes a word you say, especially when you’re obviously so invested in one point of view that you get all emotional.

    Thanks for the reference, but it doesn’t seem to say which of the models use 3D radiation codes. Is that the link you intended? Whereas my reference did say that they used 1D codes. Although I suppose it’s possible that it’s only NASA who are behind the times. References do have to be relevant.

    This warming cannot be natural.” Excellent! Even the IPCC only give it 90%, but I’m clearly talking to a real expert here. Go on then. Prove it.

  22. Yeah, you think people are going to form an opinion about a scientific issue based on who’s politest? You ask me to be considerate? Look at your own behaviour.

    You misread, as ever. Your reference spoke of plane-parallel GCMs. These are not the only type of GCM. One doesn’t always need the most sophisticated model available to investigate a problem. There really is a very consistent pattern here, that you only read so far as you think you need to to confirm your preformed opinion.

  23. On this occasion, I am open to persuasion. I don’t find it unbelievable that some subset of GCMs now use 3D code, I won’t be making the claim again until I know one way or the other, and I’m genuinely interested to know what GCMs have what capabilities. As I showed, I did have a reason for thinking that GCMs still used the plane-parallel approximation, but it makes no big difference for me if they don’t.

    But the pattern I’m seeing is that you make a claim and then can’t seem to back it up. You instead demand that I back it up for you.
    I’ve had a very quick look just now, and can’t see anything definitive. But I have here someone who has the information I’m interested in – who has clearly seen some evidence that modern GCMs now use 3D radiation code. It makes sense to ask, surely? Here’s your big chance! I’m actually asking for your contribution, seeking your expertise. Isn’t this what you’ve always wanted? Which GCMs use what methods and since when? It’s an easy enough question.

  24. Lots has been written, and I do not have the time to read it all. Is there any evidence of “Scientist” having explained under what circumstances he or she would change their mind?

    By the way…it is not strictly matter of politeness. A good argument is a good argument even when expressed rudely. The trouble is when rudeness is a substitute for arguing. One has only so much willingness to exchange views with somebody throwing toys out of the pram.

  25. I don’t mind rudeness, but I am aware that we are guests on the blog owner’s property, and I don’t want to be inconsiderate to him. If he wants a site that he can show to friends and family, or that people can use while at work, then one would hope people would behave as they would if they went to visit somebody else’s home, and not be spitting ‘baccy on the carpet. While it’s lots of fun to wind the trolls up and makes them look bad, in doing so I bear a tiny bit of the responsibility for encouraging them. I take that seriously. Raving and frothing is fine, but letting them get unpleasantly antisocial isn’t.

    I don’t think you can expect the evidence of mind-changing to be so obvious. The best you’ll likely get is that he stops arguing on a particular topic and ignores the question. I would assume that if he had a good answer he’d use it, so a sudden silence is possibly meaningful. Although he may just have got bored of it, or wants to concentrate his attack on what he perceives as the most vulnerable parts. It’s hard to tell.

    I’m sure he’d tell you that for him to change his mind he’d have to be wrong, and that he isn’t. That has certainly been the attitude so far. He never concedes on anything. It gives a fascinating insight into a particular sort of mind set commonly found in Believers of various sorts. I’ve been having a think about the psychology of the phenomenon, although I don’t want to contaminate the experiment by talking about it. But I will be interested to see if even on an easy question on a point he himself raised, he can be coaxed into providing proper, unassailable evidence. He exhibits an interesting character, well worth a little study.

  26. Remember that the owner of this blog is a proven liar, and also encouraged his child to think that he was ‘proving the IPCC wrong’. His ethical standards are abysmal.

    Stevo, you’re a patronising cunt. Fuck off.

  27. Nice language, “Scientist”…..

    Certainly, it is clear from this blog that the debate about climate is not over. I would expect “Scientist” would say “Only the f@#$ing deniars, full of s*%t and ignorance are debating”, but considering other things where the debate IS over (the Earth is round, etc.) we find no debates. Even if it is a significant group of non-scientists debating the issue, there IS debate. And debate is healthy, though I am concerned that I might catch some sort of digital dysentery from “Scientist”‘s comments…..

    I’m sure any readers who have kids know that the ones that are yelling and screaming profanities, are usually wrong.

  28. Scientist,

    One paper, even if peer reviewed, is not PROOF that hurricane strength is increasing. Try again.

    Glaciers have been melting since the 1800’s. Try again.

    .2 deg C per decade has been seen before. Try again.

    Where is the ocean temp increase. According to recent paper using the unmanned buoys there has been none since 2003. Try again.

    Where is the upper trop temp increase greater than surface and strat. Try again.

    NASA just announced PDO flip. Along with the solar TSI reduction I guess WEATHER will COVER UP AGW AGAIN??


    By the way, have you gotten any SINGLE model to actually match temp parameters with a reasonable accuracy??

    I really get a kick out of alledged adults trying to act like a SUITE of Models with numerous FUDGE FACTORS have ANYTHING to tell us about climate!!


  29. Scientist,

    I hear you put a lot of store by ALBEDO. Why did the Arctic ice come back this winter after such a LARGE albedo change??

    Maybe for the same reason that even though CO2 has such a LARGE POSITIVE FEEDBACK affect the temps dropped precipitously last year even though CO2 is ALLEDGEDLY at historically record levels??

    Maybe you can also explain why the galloping glaciers in Greenland have suddenly slowed back down to a trot??


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