Models Methods Software

Dan Hughes

The CRU Info Leak . . .

I’m thinking there just might be some problems in some of the GCM software.

1255553034.txt

In the middle of October 2009, Tom, Gavin, Mike, and a bunch of other people discuss models, measured data, and presentation of comparisons.

I’ve added some bolding.

See the whole thing to ensure that The Context is proper.

From: Tom […]
To: Gavin […]
Subject: Re: BBC U-turn on climate
Date: Wed, 14 Oct 2009 16:43:54 -0600
Cc: Michael […], Kevin
[…], Stephen […], Myles […], peter […],
“Philip […], Benjamin  […], Thomas […], Jim, Michael  […]

<x-flowed>
Gavin,

I just think that you need to be up front with uncertainties
and the possibility of compensating errors
.

Tom.

+++++++++++++++++++++++++

Gavin  […] wrote:
> Tom, with respect to the difference between the models and the data, the
> fundamental issue on short time scales is the magnitude of the internal
> variability. Using the full CMIP3 ensemble at least has multiple
> individual realisations of that internal variability and so is much more
> suited to a comparison with a short period of observations. MAGICC is
> great at the longer time scale, but its neglect of unforced variability
> does not make it useful for these kinds of comparison.
>
> The kind of things we are hearing “no model showed a cooling”, the “data
> is outside the range of the models” need to be addressed directly
.
>
> Gavin
>
> On Wed, 2009-10-14 at 18:06, Michael  […] wrote:
>> Hi Tom,
>>
>> thanks for the comments. well, ok. but this is the full CMIP3
>> ensemble, so at least the plot is sampling the range of choices
>> regarding if and how indirect effects are represented, what the cloud
>> radiative feedback & sensitivity is, etc. across the modeling
>> community. I’m not saying that these things necessarily cancel out
>> (after all, there is an interesting and perhaps somewhat disturbing
>> compensation between indirect aerosol forcing and sensitivity across
>> the CMIP3 models that defies the assumption of independence)
, but if
>> showing the full spread from CMIP3 is deceptive, its hard to imagine
>> what sort of comparison wouldn’t be deceptive (your point re MAGICC
>> notwithstanding),
>>
>> perhaps Gavin has some further comments on this (it is his plot after
>> all),
>>
>> mike
>>
>> On Oct 14, 2009, at 5:57 PM, Tom  […] wrote:
>>> Mike,
>>>
>>> The Figure you sent is very deceptive. As an example, historical
>>> runs with PCM look as though they match observations — but the
>>> match is a fluke. PCM has no indirect aerosol forcing and a low
>>> climate sensitivity — compensating errors. In my (perhaps too
>>> harsh)
>>> view, there have been a number of dishonest presentations of model
>>> results by individual authors and by IPCC
. This is why I still use
>>> results from MAGICC to compare with observed temperatures. At least
>>> here I can assess how sensitive matches are to sensitivity and
>>> forcing assumptions/uncertainties.
>>>
>>> Tom.

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November 27, 2009 - Posted by | Uncategorized |

8 Comments »

  1. Hi Dan,

    I wish these scientists were in the habit of making these kinds of statements in public as well as private. You certainly won’t find them uttering anything remotely resembling this stuff on the RealClimate blog.

    Richard Feynman once said, in his famous “Cargo Cult Science” address: “I would like to add something that’s not essential to the science, but something I kind of believe, which is that you should not fool the layman when you’re talking as a scientist. … I’m talking about a specific, extra type of integrity that is not lying, but bending over backwards to show how you’re maybe wrong, that you ought to have when acting as a scientist. And this is our responsibility as scientists, certainly to other scientists, and I think to laymen.”

    Do you think Feynman would feel differently now? I don’t.

    Comment by gmcrews | November 27, 2009 | Reply

    • I really wish that Feynman was around to give us his views on this mess. He also said “I’ve had the advantage of having found out how hard it is to get to really know something, how careful you have to be about checking the experiments, how easy it is to make mistakes and fool yourself.” From The Pleasure of Finding Things Out page 22. In 1964 Jacques Barzun published Science: The Glorious Entertainment, a critique of science in our culture, and the love/hate feelings that it engenders in our society and it reads well today. David

      Comment by David Stern | February 27, 2010 | Reply

      • The most important outcome from my education was to learn that it is critically important to need to continue learning; forever.

        The most important outcome from my career has been to discover how much hard work is required to get initial ideas and concepts ( those initial EWAGs ) straightened out and finally resting on firm theoretical foundations.

        And what Richard Hamming said, “The objective of computing is insight, not numbers.”

        http://www-history.mcs.st-and.ac.uk/Quotations/Hamming.html

        Comment by Dan Hughes | February 28, 2010

  2. The software picture is getting some attention.

    No One Peer-Reviews Scientific Software

    Scientists Are Not Software Engineers

    Along with

    Climate Science and the Inner Ring

    Comment by Dan Hughes | November 30, 2009 | Reply

  3. Wow, researchers disagreeing. Fraud, for sure …

    Comment by dhogaza | December 19, 2009 | Reply

    • dhogaza,

      No one here said fraud.

      That is your word, not anyone else has used it.

      If you begin to deteriorate into your usual MO on this blog, you will be banned.

      Comment by Dan Hughes | December 19, 2009 | Reply

  4. Tom, with respect to the difference between the models and the data, the fundamental issue on short time scales is the magnitude of the internal variability. Using the full CMIP3 ensemble at least has multipl individual realisations of that internal variability and so is much more suited to a comparison with a short period of observations

    For instance, do you understand what this means?

    And how it pertains to this:

    The kind of things we are hearing “no model showed a cooling”, the “data is outside the range of the models” need to be addressed directly.

    Nothing mysterious or shady at all here. Makes perfect sense.

    Comment by dhogaza | December 19, 2009 | Reply

  5. @dhogaza (Comment 4)

    GCM software is being used in support of potentially high-consequence decisions (and the timing of those decisions). The software engineering consensus is that high-consequence software must undergo rigorous IV&V. The climate modelers seem to deny this consensus. Dan has been drawing attention to this fact for some time. He has even been providing suggestions and insight into how rigorous IV&V could be applied to climate science software. As a person knowledgeable about high-consequence technical software quality assurance in the nuclear field, I believe his efforts to be useful and worthy of serious consideration.

    However, at RealClimate, I have seen where Dan’s comments, observations and suggestions have been misunderstood and less than, shall we say, cordially received.

    Now we have evidence that the dismissive attitude taken may not have even been sincere. And in a comment above I make the observation that, in any event, the attitude is clearly not scientific — Feynman-wise.

    Do you have any thoughts about the actual subject of Dan’s post? Do you think it actually better to be more confident about the reliability of the GCMs in public than within the climate clique? Rather than the Feynman-like reverse? To avoid rigorous IV&V in order to appear more confident? Do you think the GCMs reliable? Has the reliability been properly verified, validated, and accredited already?

    I think I know how Dan would answer these questions.

    George

    Comment by gmcrews | December 19, 2009 | Reply


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