Climate models do not justify even precautionary action

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-knownIPCC assertions.

“those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least 100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lackfull scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”Skeptic Magazine, Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns outfor reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least 100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lackfull scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”Skeptic Magazine, Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns outfor reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least 100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lackfull scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”Skeptic Magazine,Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns outfor reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“…those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least ±100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lack…full scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”  Skeptic Magazine—Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns out—for reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“…those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their pre dictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least ±100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lack…full scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”  Skeptic Magazine—Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns out—for reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“…those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least ±100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lack…full scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”  Skeptic Magazine—Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns out—for reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

“…those who advocate extreme policies to reduce carbon dioxide emissions inevitably base their case on GCM projections, which somehow become real predictions in publicity releases. But even if these advocates admitted the uncertainty of their predictions, they might still invoke the Precautionary Principle and call for extreme reductions ‘just to be safe’. This principle says, ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.’ That is, even if we don’t fully know that CO2 is dangerously warming Earth climate, we should curtail its emission anyway, just in case.

However, if the present uncertainty limit in General Circulation Models is at least ±100 degrees per century, we are left in total ignorance about the temperature effect of increasing CO2. It’s not that we, ‘lack…full scientific certainty,’ it’s that we lack any scientific certainty. We literally don’t know whether doubling atmospheric CO2 will have any discernible effect on climate at all.”  Skeptic Magazine—Patrick Frank

Frank’s article is well-written, well-documented and brim-full of insight into the limits of GCM modeling. He writes without jargon and with no more algebra than is absolutely necessary: remarkably little as it turns out—for reasons that are illuminating in themselves.

Unfortunately, the companion article published by Sceptic Magazine, in support of the AGW propositions offers little more than a repetition of well-known IPCC assertions.

7 Comments

  • Mitchell Porter wrote:

    Frank’s article has been briefly discussed on at least two blogs by climatologists, and his argument dismissed as invalid. They say that in order to derive his cumulative error (”±100 degrees per century”), he makes mathematically erroneous assumptions about the GCMs. It is going to require a little more study on my part to truly grasp the problem, but it seems to involve, in part, treating a number derived from averaging over many simulation runs as if it were the property of an individual simulation run.

    http://www.realclimate.org/index.php/archives/2008/05/what-the-ipcc-models-really-say/#comment-86894

    http://initforthegold.blogspot.com/2008/03/why-is-climate-so-stable.html?showComment=1210739520000#c8782544473864969372

    Since the article is gaining a little attention, I imagine someone will write a more thorough rebuttal at some point.

  • Thanks for the references Mitchell. I read the debate between Frank and Tobis carefully. I can’t say that I’m able to adjudicate on the technical issues of climate modeling. But I’ve had a lot to do with economic modeling over the years (Tobis has a low opinion about economic rationality, by the way). If that experience is relevant then, reading between the lines, I’d say that Tobis is evading the issues.

    It seems to me that he dismisses Frank’s argument about the relevance of uncertainties in initial conditions (iterated through a model) without actually answering it. His response to Frank is really ad hominem: ‘You don’t understand climate … what you say holds for weather i.e. instantaneous prediction, but not for climate. Your claims would be considered naive by my colleagues/fraternity etc etc’.

    I’ve always found that sort of argument unconvincing. If an economic modeler was unable to respond to criticisms of model mechanisms except by saying, ‘it’s not done that way’, or ‘that’s not the issue we’re interested in’—as they sometimes did— I started to pay much less attention. I found that after that sort of response the debate becomes ‘hieratic’.

    On the whole I think Pat Frank makes a very plausible argument. But I recognize that it’s impossible—for now, at least—to ‘carry the day’ in this debate. There are too few physical facts/mechanisms and too much questionable use of statistics.

  • Mitchell Porter wrote:

    Frank’s critics are unanimous that his main “result” – the spectacular amplification of error – is purely an artefact of his approximation and has nothing to do with the behavior of the GCMs he is discussing.

    Here’s what I gather is happening.

    A GCM has a large number of adjustable parameters. To get these temperature trends, the parameters are set, a large number of individual runs are performed, and then they are statistically aggregated. So you’ll get a mean and a variance. The variance is apparently constant over time.

    Frank takes this model output and makes it the input to something much simpler, a linear fit to the evolution of the mean temperature as predicted by the GCMs. Unsurprisingly, errors in the initial conditions of his linear equation then grow linearly with time. But this demonstrates absolutely nothing about the GCMs. What he (or someone) needs to do is to look at what uncertainty in those model parameters does to the variance of the predicted temperature.

  • Mitchell Porter wrote:

    P.S. I see what you mean about Tobis vs economics, though (I’m just viewing his other posts).

  • Pat Frank wrote:

    Mitchell wrote, in #1, “…[the error] seems to involve,… treating a number derived from averaging over many simulation runs as if it were the property of an individual simulation run.

    In the first place, the SRES simulations on which the error operated are composedof averaged multiple GCM runs. So, the quoted objection is out of place.

    Secondly, individual GCM runs exhibit far more error than do averages of many runs and so, if anything, the uncertainty in the long-range predictions of individual runs would be even larger than the estimate given in the Skeptic article.

    That is, the given uncertainty represents a lower-limit estimate.

    Regarding your follow-up comment, the line in Figure 2 is not a linear fit to the displayed GCM outputs.  It is an entirely independent calculation, as shown in the derivation given in the Supporting Information. 

    Gavin on RealClimate repeatedly and erroniously dismissed that line as a fit, which it is not, and which dismissal rests upon a misrepresentation.

    The line in Figure 2 shows that all one need do to reproduce global average temperature projections of complex GCMs, with respect to the effect of increasing GHG’s, is to linearly propagate the GHG forcing.

    This in itself is an extraordinary result, given all the heavy-breathing about how climate is rife with complex feedbacks and non-linear chaotic excursions. One sees none of that in the GCM-produced temperature trends.  It’s as though, in GCMs, all the climate feedbacks average out to zero—at least across 80 to 120 years. That hardly seems realistic.

    As the Figure 2 line closely reproduces GCM global average temperature outputs, it is entirely justifiable to use the same generating equation to estimate the uncertainty in those outputs.

    It seems as though the uncertainty in intermediate climate states are typically not propagated step-wise forward in time-wise GCM projections. One wonders on what grounds this exclusion can possibly be justified.

    Mitchell, you also suggested that, “What he (or someone) needs to do is to look at what uncertainty in those model parameters does to the variance of the predicted temperature.

    In the article, I mentioned searching the climatology literature without luck for such a study. Don’t hold your breath waiting for a climate modeller to do it. The parameter uncertainties (among others) would have to be propagated through the physics. The project would be difficult, and extremely revealing.

  • Thanks for the clarifications, Patrick.

    I thought the demonstration in your Figure 2b (and the ‘complex’ formula that accompanied it) was hilarious.

    Peter

  • Pat Frank wrote:

    Thanks Peter, and thanks for your interest. It’s been quite a sleigh-ride. So far, I’m still aboard.

    Quite clear is it that the IPCC have been playing fast-and-loose with proper uncertainty estimation, and that they are a closed and rather paranoid shop in contradiction to their own rules and standards.

    Over at ClimateAudit.org, Steve McIntyre has been following David Holland’s FOIA attempts to have the IPCC release its reviewer notes, in accordance with its supposed commitment to openness and transparency. Mr. Holland is being stonewalled by bureaucratic stratagem.

    So, if you have some influence, or come to a position of governance again, it would be of great benefit to use those powers to require a full and independent audit the IPCC.

    Especially how the IPCC have accommodated reviewer objections and followed their own rules of data quality.  Steve McIntyre has documented some serious lapses at his site.

    Australia could take the lead in calling for an audit, or even doing it in-house, and the IPCC could not legitimately refuse. What, after all, have they to hide if all is above-board? An honest broker welcomes an audit.

    Far too much is riding on climate change to allow the IPCC to keep its hand hidden.

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