Bishop Hill Unqualified evidence
Dec 21, 2013 Climate: Models Climate: Oceans Climate: Statistics Royal Met Soc Following my post on the Royal Meteorological Society's evidence to the AR5 inquiry, Doug McNeall and I had a long and interesting exchange on Twitter. Although he arrived at his point somewhat elliptically, Doug appeared to want to suggest that although in Ed Hawkins' graph the observations are on the cusp of falling outside the envelope described by 90% of model runs, this did not actually represent falsification. In his view, the test was too harsh.
The precise determination of when the observations should be seen as inconsistent with the models is one for the statisticians, and I know that Lucia, for one, disagrees with Doug's view (and I feel pretty sure that Doug Keenan will say that they are both wrong). However, this is not actually germane to my original point, which is that the poor performance of the models to date - as represented by Ed's graph - needs to be communicated to policymakers. We are without doubt less confident than we were that the model ensemble captures the true behaviour of the Earth, even if we are not (in Doug M's view at least) absolutely certain that it does not.
So returning to the Royal Meteorological Society's evidence, I asked Doug why they made the following unqualified statement of confidence in the models (my emphasis):
The Report devotes Chapter 9 to a comprehensive, balanced and realistic evaluation of climate models which is based on the published literature and draws extensively on the results of the Coupled Model Intercomparison Project Phase 5 (CMIP5). As stated in the report (Chapter 9, final draft) climate models are based on physical principles, and they reproduce many important aspects of observed climate. We agree with the report when it states that both these aspects contribute to a “confidence in the models’ suitability for their application in detection and attribution studies and for quantitative future predictions and projections”, and when it notes that “whereas weather and seasonal climate predictions can be regularly verified, climate projections spanning a century or more cannot. This is particularly the case as anthropogenic forcing is driving the climate system toward conditions not previously observed in the instrumental record, and it will always be a limitation.”
I was rather taken aback by Doug's response:
You call that unqualified!? Ha!
To me, the part that I have highlighted seems absolutely to represent a statement of unqualified support for the models. The remainder the merely says that scientists can't say whether they are any good in the very long term. I can only assume that Doug's response is based on a narrow reading of the text - in other words that they are only saying that the basis in physics and the hindcasting ability contribute to a "suitability for prediction", not that such suitability has been achieved. If so I would say that the Royal Meterological Society has grossly misled the inquiry.
But even if this is the case, we know that the models run too hot over the medium term and the short term. We know that they incorporate the wrong value for aerosol forcing, so we would expect them to run too hot anyway. We know that scientists are now theorising that heat is currently being transported into the deep ocean by a process as yet undetermined and entirely unrepresented in the models.
So even if Doug's position is "the models are not yet falsified", we have to ask where is the communication of the known problems with the models. Why has the Royal Meterological Society not explained the situation to politicians?
Reader Comments (61)
...I was rather taken aback by Doug's response: "You call that unqualified!? Ha!"
I have already explained earlier how to read the Whitehall-speak that the comment is made in. It does not express unqualified support - it says that the models are crap.
Of course it says it in such a way as to be interpreted as supporting the models. ALL Whitehall briefs are written intentionally to be capable of supporting ALL points of view. This allows a politician to take any action he wants and to still claim justification. It is part of the Sir Humphrey code - civil servants will always get ministers off the hook, so long as ministers do what the civil servants tell them...
I accept everything written by HAS.
Yet, I am extremely uneasy about almost every aspect when considering climate models.
Dec 21, 2013 at 10:37 AM | Manniac
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LOL ! Take this one of theirs and replace "Greek economy" with CAGW. Equally bankrupt ;)
Duh ! this one ... http://www.youtube.com/watch?v=rK0De210TBQ&feature=share&list=SPDB223DCE781D0606&index=2
HAS:
Reading this I wondered what the odds were for this statement in a future IPCC report: "Come back, Guy Callendar, all is forgiven."
Models can fail if they rely on the wrong equations for the purpose.
The early experiments of Tyndall and Arrhenius around the 1860s+ did not measure the radiation energy produced at IR wavelengths split by a rock crystal. It has since been assumed that basic classical thermodynamic equations of Maxwell and Planck, as converted to give the Stefan Boltzmann relation of the 1880s, are correct. In these the power of 4 now applied to the absolute temperatures is derived through integration of prior equations where the precursor of the 4 is a geometric term involving discs & spheres as in pi*r^2 and the like eventually giving, where u = internal energy density,
du/4u = dT/T
which leads immediately to u = A T^4 , with A as some constant of integration.
http://en.wikipedia.org/wiki/Stefan–Boltzmann_law#Integration_of_intensity_derivation
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Thus the whole theory of GHG global warming rests on the correctness of classical thermodynamics. I'm not suggesting they are wrong, but I've not read of studies that look back at foundations like these. Related factors like the wisdom of invoking black body radiation models enter the bigger picture. Prudence might perhaps require such another look - but it could easily have been done without it coming to my knowledge yet.
Remember, in matters like radiation balance at top of atmosphere, it takes only a tiny deviation from the classical equations to show up as an error or uncertainty. Also, what happened to the A term quoted above?
Does anyone know of well-designed bench experiments where the applicability of SB has been confirmed through measurement, ditto for heat involved when CO2 is put into the system?
"Does anyone know of well-designed bench experiments where the applicability of SB has been confirmed through measurement, ditto for heat involved when CO2 is put into the system?"
Geoff, both of these points were covered in the "Can Trenberth do sums?" discussion thread (last used in September). In brief, the NASA Diviner experiment experimentally confirms the applicability of the SB equation in planetary thermodynamics.
The extract quoted looks like unqualified praise to me. I hope that Doug M and Doug K might elaborate on why they don't share that view.
I would like to commend the NIPCC report 'Climate Change Reconsidered II' to those who raise an eyebrow at any suggestion that AR5 provides 'a comprehensive, balanced and realistic evaluation of climate models' . (Full disclosure: I am very chuffed to have played a tiny part in helping the NIPCC get that report out.)
The chapter specifically on climate models is available for free here: http://heartland.org/media-library/pdfs/CCR-II/Chapter-1-Models.pdf
On second thought, I'd especially recommend that chapter to those who don't raise the aforementioned eyebrow about the AR5 effort.
HAS
One unanswered question, however, is where do the models stand when the policy makers have already decided what actions to take, aka policy-based evidence making?There is certainly some evidence about the place that "the models" are being tweaked to produce the scary scenarios that will enable to the politicians to have their wicked way regardless of the empirical evidence and at the very least a suspicion that there are those with a vested (ie financial) interest in keeping the scare running who are less than forthright in their interpretation of the evidence.
That's the trouble with models; they can be made quite legitimately (almost) to say just about anything the modeller would like them to say. How do you overcome confirmation bias and noble cause corruption, not to mention naked greed?
My understanding of the recent statistical issues are:
IPCC modellists assume that temperatures follow a first order autoregression of a liear trend. Based on this assumed statistical relationship being correct, real temperatures have failed to change significantly for the last 15-20 years, depending of data source. This 'problem' has caused murmerings and there has been much discussion over the temperature hiatus.
Doug Keenan then asks a question that should have been asked in the first place. How well does the actual temperature data match the first order autoregression model? Answer; Correlation from 1850 is 0.001.
This is the real point. None of the temperature rise over the last 160 years is stastically significant. The hiatus of the last 15-20 years is a red herring.
This is my understanding. Can someone show me where I I'm going wrong?
If a better model is used, which matches actual data better, what happens to the error bars regarding statistical significance and can we extract a signal from the noise ?
Whether called "falsification" tests or not, it is the duty of the originators of the AGW speculation/hypothesis to suggest every possible way of challenging it. Only by passing such challenges can any "confidence" be vested in it. But they steadfastly refuse to offer or even accept tests and challenges. They apparently want their speculation to graduate to "theory" and "law" status directly.
Bad enough if it were, say, an abstract issue like string theory. Abominable when it purports to be guidance for governance and feeding of the planet!