

Climate models fail on the test stand

By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
[German text translated/edited by P Gosselin)

20 years ago climate models were celebrated as a huge breakthrough. Finally we were able to reproduce reality in the computer, which had been becoming ever more powerful and faster. Everyone believed that only minor adjustments were necessary, and the target would be reached. But when the computer-crunched results were finally compared to reality, huge unexplained discrepancies appeared.

In parallel, paleo-climatologists produced increasingly robust reconstructions of the real climate development, which served to make the computer problems even more glaring. Month after month new papers appeared exposing the major problems of the climate modelers. Model tests were preferably started in the middle of the Little Ice Age, around 1800, because the warming seemed to fit well with the rise in CO2 emissions.

But if one goes back 1000 years, the model technology falls apart.

In March 2016 Fabius Maximus pointed out the obvious: The models have to be more strictly tested and calibrated before they can be approved for modeling the future.

[…] The policy debate turns on the reliability of the predictions of climate models. These can be tested to give “good enough” answers for policy decision-makers so that they can either proceed or require more research. I proposed one way to do this in Climate scientists can restart the climate change debate & win: test the models!— with includes a long list of cites (with links) to the literature about this topic. This post shows that such a test is in accord with both the norms of science and the work of climate scientists. […] Models should be tested vs. out of sample observations to prevent “tuning” the model to match known data (even inadvertently), for the same reason that scientists run double-blind experiments). The future is the ideal out of sample data, since model designers cannot tune their models to it. Unfortunately…

— Thomas R. Knutson and Robert E. Tuleya, note in Journal of Climate, December 2005.

There is a solution. The models from the first four IPCC assessment reports can be run with observations made after their design (from their future, our past) — a special kind of hindcast.”

Another large point of criticism on climate models is the so-called “tuning”. Here climate models are adjusted so that they nearly produce the desired result. This takes part mostly in clandestine rooms behind closed doors where there is little transparency. Hourdin et al. 2016 described the problem in detail in an assessment paper. Judith Curry sums it up best:

Two years ago, I did a post on Climate model tuning,  excerpts: “Arguably the most poorly documented aspect of climate models is how they are calibrated, or ‘tuned.’ I have raised a number of concerns in my Uncertainty Monster paper and also in previous blog posts.The existence of this paper highlights the failure of climate modeling groups to adequately document their tuning/calibration and to adequately confront the issues of introducing subjective bias into the models through the tuning process.”

Think about it for a minute. Every climate model manages to accurately reproduce the 20th century global warming, in spite of the fact that that the climate sensitivity to CO2 among these models varies by a factor of two. How is this accomplished? Does model tuning have anything to do with this?”

Read the entire post at Climate Etc.

In November 2016 in the renowned journal Science, Paul Voosen described the necessity of ending all the secrecy and black boxes in order to allow some public transparency:

Climate scientists open up their black boxes to scrutiny

38 responses to “Recent Research Shows Climate Models Are Mostly “Black Box” Fudging, Not Real Science”

  1. John F. Hultquist

    As always, thanks for making these articles available to us.
    I read NTZ and wonder what we miss by not having a French and a Russian
    “to-English” person such as you.

    The following may be of interest to readers with a concern about climate models:
    Back on the 10th, Luboš Motl wrote about climate models; Link below. His was a different approach (triggered by a Scott Adams (Dilbert) post) but arriving at the same conclusion — Climate models are not science.
    The 3 posts, NTZ, Adams, and Motl, make a good package.

  2. Sunsettommy

    How can models of any kind be good science,when they run to year 2100?

    That is 83 years in the FUTURE!

    How can such guesses be testable, reproducible,when it hasn’t happened yet for many more decades?

  3. Editor of the Fabius Maximus website

    Thanks for posting this excellent article. You go to the heart of the public policy discussions about climate change — and why they failed to accomplish much in the US despite expenditure of vast resources over three decades.

    The calls for transparency are even now inadequate. To see what’s necessary, recall what happens in disaster films — like “When Worlds Collide”. Scientists fully display their data and conclusions, asking other scientists to confirm them.

    The current warnings began with James Hansen’s Senate testimony in 1988. Scientists have closely held their data, saying “Trust us.” The US public has not found this a compelling case.

    We need climate scientists to make their case before a multi-disciplinary team of scientists — geologists, software engineers, statisticians, experts in modeling, chemists, etc — for evaluation. The result won’t be perfect (only Heaven is perfect, but you must die to get there). But we’ll know more than we do today.

    For details about what went wrong and how to fix it see:

  4. tom0mason

    It appears that an awful lot of climate guesswork and assumptions have been encoded into these ‘climate model’ just to give the veneer of them being ‘scientific’.
    The modelers by their own admission know the models fail to accurately model clouds, precipitation, and so much more. For more of the inside view see — just click on the hexagons to see.
    Also see for the CMIP5 and CMIP6 latest resolutions of bashing a square peg into a round hole.

    Also of interest is
    Where they say —
    “We should also restate that this approach obviously cannot create model ability. Applying this approach to a poor ensemble of misleading models will not create a robust projection, and the very real possibility that all or most models are missing key processes remains a key concern.
    There is always value in improving individual models.
    Finally, as it stands the EDT relies on an RMSE type metric—essentially constraining mean and spatiotemporal variability—when in many applications other metrics are more important (e.g., extreme values).”

    An admission that there are misleading models and ensembles of models?

  5. tom0mason

    If the point of these models is to indicate real possible future trends then most assuredly they have failed. They require thousands of iterations with an array of tuning values to give near real hindcasted results. How could anyone have any confidence that these models can ‘project possible future scenarios’ when they perform so poorly looking back over a very short (known) climatic period?

    As J Curry’s quoted paper says —

    “The art and science of climate model tuning
    Frederic Hourdin et al.

    ….The use of objective methods could also be promoted at all the stages of model tuning, in order to render the process more efficient. However, objective tuning approaches should be used with caution. Because of the approximate nature of models and because of observations uncertainties, it is impossible to retain one unique parameter set as an objective criteria. Formalizing the question of tuning addresses an important concern: it is essential to explore the uncertainty coming both from model structural errors, by favoring the existence of tens of models, and from parameter uncertainties by not over-tuning. Either reducing the number of models or over-tuning, especially if an explicit or implicit consensus emerges in the community on a particular combination of metrics, would artificially reduce the dispersion of climate simulations. It would not reduce the uncertainty, but only hide it.
    We end by expressing the hope that this article will encourage both a systematic effort by the community to document this arcane aspect of model construction, and for more people to join a vigorous debate on model tuning and evaluation.”

    So much for those who used the models as evidence to say “science has spoken”, if it has (spoken) then all it has done is to raise more doubt about our understanding of the action of CO2 in this planet atmosphere.

  6. CO2isLife

    If something is understood, it can be modeled. Climate experts don’t even come close to modeling the climate.

    1. SebastianH

      Because you don’t allow comments on your blog …

      In your linked post and further in you are using a chart which shows the cooling rates in certain wavelengths of the spectrum. This chart was generated using models and indeed, there is no warming caused by CO2, isn’t there. What should make you suspicious is that there is also no warming due to water vapor. The only source of atmospheric heat seems to be ozone.

      Making my point: the backradiation from the atmosphere is not warming the atmosphere, it is causing the surface to warm.

      1. Sunsettommy


        What made you think that chart is a model?

        It doesn’t say it is one,maybe you can help us here?

      2. AndyG55

        Come on seb, how did that water vapour get into the atmosphere.

        Try, JUST ONCE, to THINK, despite the AGW anti-knowledge blockage in your mind.

        The net effect of H2O in the atmosphere is COOLING.

      3. tom0mason

        Mr Troll Seb,
        I have answered that question for you three time but you are too dumb to recognize the truth. Are you special needs or what?

      4. SebastianH

        To keep it short and simple …

        the image is taken from this paper with the title “Line-by-line calculation of atmospheric fluxes and cooling rates”. Any further questions?

        you are describing what the image shows and the keywords are “in the atmosphere”. The backradiation (from water vapor, etc) is affecting surface temperatures, not atmospheric temperatures.

        What question and why the insult?

        1. AndyG55

          WRONG, seb

          Use your imagination again, maybe you will dream up some other fallacy.

          You very obviously DID NOT THINK. !!

          A parrot would do as well you have ever managed.

          H2O has a net cooling effect on the surface of the Earth..

          End of story !!

        2. AndyG55

          Start your own blog, seb

          I bet NO-ONE listens to you there either.

          You are empty, science-free, and NIL-informed.

          Why be a low end TROLL/SHILL on a real science site when you have so much to offer to your fellow AGW bletheren?

        3. SebastianH

          In a world without backradiation you might be right … unfortunately this has been measured extensively. Do you need a paper for that too?

          This will be my last reply to any of your comments containing insults.

          P.S.: you’ve been a very persistent fan of mine for “no-one listens” 😉

          1. AndyG55

            Everything you think you know is massively TAINTED by AGW misinformation. Anti-knowledge.

            There is nothing anyone can do about it, except for you to start again at the beginning.

            I just have to make sure that anyone reading your nil-informed posts is aware of that fact.

            Still not one paper showing that CO2 causes warming in a convective atmosphere.

            You even seem to think that H20 warms the Earth’s surface.. I don’t think I would need to point out, even to a 5 year old, just how massively nil-informed you are.

          2. SebastianH


            If you would some day find the time to actually quantify how much energy (in W/m²) is transfered from the surface to the atmosphere by evaporation and how much of that energy is transfered back to the surface, don’t be surprised.

            Add to it cloud forcing and the greenhouse effect of water vapor and you get net warming due to the existance of water. Of course, if you live in a world where the latter one doesn’t exist, water doesn’t cause the surface to be warmer than without it.

          3. AndyG55

            Seb actually BELIEVES that H2O warms the surface of the Earth.

            Also believes that CO2 causes warming in a convective atmosphere.

            One day, maybe it will think enough to figure out how that H2O got into the atmosphere in the first place. !

            seb Think???? not going to happen !!

          4. AndyG55

            Again, we get this MAGICAL AGW creation of energy, where H2O gains more energy as it gets higher.

            Bizzare anti-science to say the least.

            The net effect of H2O atmospheric transport is to carry energy to the cloud height and above, as part of the COOLING/REGULATING mechanism of atmosphere.

          5. AndyG55

            Governed, of course, by the gravity based pressure/density/temperature gradient.

          6. AndyG55

            “This will be my last reply to any of your comments containing insults.”

            You just proved yourself to be a LIAR !

            Cannot even tell the truth to yourself, can you.

            You cannot help but respond. You are hooked.

            At my beck and call.

            Come here, little AGW wormy-shill. !!!

        4. tom0mason

          “What question and why the insult?”

          What question? You have a worse case of cognitive decline that I? Or is your short term memory failing?

          “…why the insults?” as a payback for all your insults to others! You don’t like it so stop doing it to others like some science deŋying AGW advocate automaton.

  7. Don from OZ

    Climate has been, and for ever will be, randomly variable.
    Every ‘model’ of climate will therefore need to have random variability.
    Every result will thus be a randomly variable result.
    Maybe sometimes it will prove to be correct but that is pure chance – NOT SCIENCE.
    Climate change may have some aspects of science pointing to it but should not be rated as science. Perhaps conjecture, or fantasy, or day dreaming may be more apt

    1. Sunsettommy

      But without the needed error range input,that should be shown on their pretty charts,it is a worthless exercise.

  8. Don from OZ

    To add to my last post.
    Is it not part of scientific method that apart from being provable, an hypothesis must also be repeatable?
    If the answer to this question is Yes then how do you prove something that is a projection into the distant future?
    And how is it repeatable?

    1. Graeme No.3

      You give them money until it turns out (in 83 years) that they were wrong. Whereupon any money left unspent will be returned to you.

  9. AndyG55

    The very FACT that the models covers such an enormous range…


    … shows that the models are just monumentally WRONG…

    … and the people writing those models haven’t got the faintest clue what they are doing.

    1. Sunsettommy

      The IPCC publish reports every 5 years,with a new round of climate models in them that are supposedly improved from the previous 5 years, yet the projected temperature change range went down only a little bit.

      Where is the long projected .30C per decade warming trend evidence?

      Where is the “hot” spot?

      Why are we getting MORE snow in the last two decades?

      Why are we getting FEWER Hurricanes and Tornadoes?

      Why are temperature extremes increasing?

      Why are people still besotted with climate models, with a nearly 100% failure rate?

  10. AlecM

    Cloud aerosol physics fiddling is done for two purposes. Firstly to create sufficient DOWN atmospheric window IR in the Kirchhoff’s Law back radiation part. Secondly to create in hind-casting the necessary imaginary positive feedback so CO2 climate sensitivity accounts for all ‘adjusted’ measured temperature rise.

    In reality CO2 CS is near zero, kept there by the water cycle, hence the need to fiddle lower precipitation than reality. This is a difficult bit of parameterisation. Allegedly the UK Met. Office is dumping it to counter the obviously wrong warming tendency.

  11. Frederick Colbourne

    Avogadro’s number (the number of atoms or molecules in a mole of any substance) converged over time.

    But as Judith Curry has explained, GCM’s (climate models) have not converged.

  12. John F. Hultquist
  13. AndyG55
    1. AndyG55

      As one commenter says

      “I have a simple rule of thumb.

      Whenever I hear the words “green”, or “smart”, I automatically think “scam”.”

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  15. Denis Ables

    If the latest report is true – that NOAA’s own data for the past 30+ years shows that radiation escaping to space is increasing, does this not basically kill ALL the alarmist models?

  16. Denis Ables

    Wow! Now the claims are that (1) the outgoing radiation is increasing, which blows all the computer models out of the water, and (2) water vapor feedback is actually negative (which also blows all the computer models out of the water.

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