Climate Models vs. Macroeconomic Models

In a podcast with Russ Roberts, Kerry Emanuel says,

there is a huge difference between climate modeling and economic modeling. We know the equations. You guys don’t. Okay? And we actually know the equations we are trying to solve. And the problems come with actually trying to solve them. And arguably our computers aren’t nearly powerful enough to really solve them exactly; and they won’t be for generations, unless there is some unbelievable breakthrough in computation.

I am surprised that he received no pushback on this point. I confess that I paused there and searched the transcript for “water vapor” or “clouds.” Not finding either, I just skimmed the rest of the transcript without reading it closely.

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15 Responses to Climate Models vs. Macroeconomic Models

  1. mb says:

    Wow, I can’t believe that guy is a scientist ( a scientist at MIT no less ). Does he really think the equations are right? no unknowns? no missing variables? the equations have everthing accounted for? I wonder why none of the equations match the data. I think scientists have forgotten that they are wrong more often then right. For every correct hypothesis there is trash can full of wrong ones. Now looking back at science, you only read about the correct hypotheses, but that doesn’t mean they were always right.

    • Andrew' says:

      This is a great point. Except you actually don’t even know the survival biased hypotheses are correct. As I keep saying, no scientist believes another scientist. Thus the entire edifice of science is built around don’t trust but verify. E.g. replication studies, citations are a way of lending some credence to your work so that the disbelief hurdle is as low as you can make it, etc. Nearly every convention in science is there to prevent charlatinism.

      What is good about science is that you can always question it. That is the good part.

      • mb says:

        I really don’t see your point unless you Kerry Emmanuel was only referring to his models. If he wasn’t (which is true) were is his verification? Is it the success of the models at predicting the climate?

  2. Tom Myers says:

    I’m mildly puzzled; I think your point needs clarification/elaboration. If you look, e.g., at the summary and table of contents of his “Atmospheric Convection” book on Google Books (Oxford University Press, 1994) you can see he thinks he knows equations to use for modeling cloud formation and behavior. Perhaps he doesn’t, and you know that he doesn’t? Or do you merely mean that he hasn’t “solved” them yet? (I’m sure he would agree with that, and not only because he says “trying to solve.”) Or do you mean that the basic enterprise of solving them is meaningless since many are non-linear and some aspects of weather, and possibly climate as well, are therefore in principle unpredictable? (But why, then, would you specify “clouds”?) Or…? I’m not sure what you mean.

    • Andrew' says:

      The meta point is they are still tuning their models but don’t know they are.

      This is exactly what economists are doing…unless you cite Mises or something ;)

    • ThomasL says:

      “Atmospheric Convection” included, not just the modeling of of the formation of clouds, but their effect is a strongly debated. Or, actually… not. It is basically ignored but well-known to be an open and unanswered question.

      Net heating or cooling? Does the increased vapor keep in heat? Does reflection of sunlight back into space prevent heating? Who knows…

      None of the current major climate models even attempt to model clouds, water vapor (or sun cycles) which is why Arnold is skeptical.

  3. Andrew' says:

    I think it is time for economists to move on. Since we’ll never know a proper price for the externality of “climate change” we can only hope to set up some kind of analogy to an NGDP futures market for it- if such a thing is even technically possible, let alone politically tenable.

    • Prakash says:

      No need to setup a market for all aspects of the climate. Initially set it up for the variables that are most important eg. rainfall in agricultural areas, periods where temperature will exceed a certain value, and so on. A well subsidized prediction market will bring in a lot of non-politically oriented research to this field.

  4. S says:

    I had the same reaction. I was hoping someone would ask “What equations do you know?”, Or better yet, don’t know. E_sys = E_in – E_out is analogous to GDP = C + I + G + (E – I), both are trivially true. In that sense, both sciences “know the equations” and it just a matter of solving them.

    Of course, physics has navier-stakes and heat transfer PDEs in general form, but at what level of specificity can climate science say “yeah, we know those”.?

  5. Paul Power says:

    This is a field in which running computer models is described as “doing an experiment” and the outputs of the same models are described as “evidence”.

    Emanuel and his ilk have a lot to answer for.

  6. William Newman says:

    The climatologists are arguably closer to knowing the equations than the economists are, but this is still a crock.

    Both economists and climate scientists could say everything is a consequence of quantum mechanics, so there! They know the equations! But that’s beside the point in practice, and even in principle it’s iffy. QM for electromagnetic forces does enjoy exquisitely good agreement with many precise experiments and does seem to describe all the important processes in the biosphere on earth, and the minor corrections for nuclear processes (which run on forces other than electromagnetism) on earth seem to be very well understood too. But in the Sun the nuclear processes are not minor corrections, and we can’t see directly what’s going on, so we’d need an exceedingly good understanding of the nuclear processes to properly infer the state of the Sun and predict its future behavior or correctly infer its past behavior. It’s unreasonably optimistic to be sure we know the equations for the Sun unless we understand the nuclear processes with the same kind of reliable accuracy we have for electromagnetic processes. The official solution to the “solar neutrino problem” is not the kind of precise well-established science that justifies trumpeting that we the equations that precisely. Maybe we really know the equations, maybe we really don’t. In the QM of electromagnetism we can compute thousands of observed properties (esp. spectral lines) to ridiculous accuracy, often far better than a part in a billion, and check them against ridiculously accurate experiments, so OK, we have some justified confidence that we really have the correct equations. In the neutrino-related observations, we tend to compare only about a dozen types of observations (chiefly neutrino capture cross sections for a handful of elements) which (for fundamental physical reasons, not incompetence) can be measured only to frustratingly low accuracy. So the electromagnetism is far more precise than Newton’s astronomy, but the nuclear stuff is probably far less precise than Newton’s alchemy. (Hard to be sure — “the last of the alchemists” was a bit secretive — but a safe guess given what’s known about chemistry-related instrumentation of the period.)

    (Admittedly we do have many strong roundabout arguments to show we’re on the right track for the important nuclear physics processes inside stars: e.g., observed isotopic distribution in the universe makes sense as residue of exploded stars. But these roundabout arguments tend to leave room for being off by more than one percent, not the same kind of thing as the insanely tight QED fit to experimental results.)

    For climate especially, this matters: e.g., the coupling of the Sun’s fluctuations to Earth’s cloud formation is likely significant and is certainly poorly understood. On the Earth end the relevant equations should describe what’s going on very precisely (but are too hard to solve for realistically messy problems in the atmosphere). On the Sun end, not only are the official equations too hard to solve, but the shaky solution to the solar neutrino problem leaves a significant possibility that the official equations aren’t a really precise description of what’s going on.

    A second significant correction is the way that plants (and parasites and whatnot) of the biosphere feed back into climate.We have every reason to think we know the fundamental equations that govern this: QM and electromagnetism are incredibly accurate for the kinds of processes we see in living organisms. But no one can solve the equations usefully accurately even for systems with a molecular weight of 1000, much less for the irreducibly complex assemblies that are important to making Earth’s life work. Even making usefully accurate predictions about the catalytic effect of a single heavy atom is really challenging, and putting the problem in water makes it harder. Arnold Kling can’t solve the equations that describe a brain, and has the good sense not to claim that we know the equations that describe economics. Kerry Emanuel can’t solve the equations that describe nitrogenase (a centrally important catalyst which involves multiple heavy atoms, with typical molecular weight apparently over 100,000).

    While Emanuel quite possibly retains some technical good sense in some other circumstances, he seems to turn it off when wearing his political hat. And I know some of the equations pretty well, and I know a little bit about public choice theory too, and I would say the public choice theory is more relevant here.

  7. Jeff R. says:

    Emanuel says:

    “If you look at the temperature records and natural logarithm of CO_2 content over 100 years, it’s a spectacular correlation between the two. Is it perfect? No, because there is natural variability. There always will be. And it’s poorly quantified. I don’t think we understand it very well. I will say that as predicted, most of the heat that you are putting into the system from excess greenhouse gases actually goes in the ocean. It’s much more massive and has a higher heat capacity. We haven’t been able to measure the ocean nearly as well as the atmosphere until quite recently. But in the last few decades it’s very clear that the heat content of the ocean is going up.”

    Maybe I am missing something, but doesn’t the second part contradict (or at least undermine) the first part? If C0_2 concentrations map very well with temperature changes over time, but most of the extra trapped heat winds up in the ocean, which is, as he says, much more massive and has a much higher specific heat capacity than air, then why doesn’t the presence of water over 70% of the earth’s surface simply swamp the effect of increased C0_2?

    David Friedman discussed a similar question on his blog, recently, but I think it went over my head at some point.

  8. It is ridiculous to trust in the integrity of a scientific “community” where prominent members of academic and government institutions announce they are willing to lie for the supposed good of the peasants.

    One might argue that these are only a few. If so, why aren’t the rest denouncing them? They should be proudly proclaiming that the data is enough and that exaggeration and lying are not needed and are in fact demeaning to science?

    Lying for climate change
    3/3/12 – Ed Driscoll   [edited]
    === ===
    People are admitting that they are willing to lie for their cause.

    •  Prof. Chris Folland, Hadley Centre for Climate Prediction and Research
    “The data doesn’t matter. We’re not basing our recommendations on the data. We’re basing them on the climate models.”
    •  Dr David Frame, Climate modeler, Oxford University
    “The models are convenient fictions that provide something very useful.”
    •  Paul Watson, Co-founder of Greenpeace
    “It doesn’t matter what is true, it only matters what people believe is true.”
    •  Sir John Houghton, First chairman of the IPCC
    “Unless we announce disasters no one will listen.”
    •  Christine Stewart, former Canadian Minister of the Environment
    “No matter if the science of global warming is all phony … climate change provides the greatest opportunity to bring about justice and equality in the world.”
    === ===

    80% of IPCC members are not climate scientists
    2/17/2009 – UddeBatt
    === ===
    [edited]  During the question and answer session at last week’s William Schlesinger/John Christy global warming debate, (alarmist) Schlesinger was asked how many members of the United Nation Intergovernmental Panel on Climate Change (IPCC) were actual climate scientists. This question came after Schlesinger had cited the IPCC as an authority for his position.

    It is well known that many or most of IPCC members are not scientists at all. For example, its president is an economist. His answer was quite telling. First he broadened it to include not just climate scientists but also those who have had ”some dealing with the climate.” His complete answer was ”something on the order of 20 percent have had some dealing with climate.”
    === ===

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