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In a recent article on the climate skeptic site Watts Up With That backed up with a published paper in Energy and Environment, Pat Frank argues that current climate simulation models are scientifically useless. In his words:

the huge uncertainty limits in projections of future global air temperatures make them predictively useless

His basic argument seems to be that the effect of varying the key inputs to Global Circulation Models over a reasonable range of plausible values gives such a large range of temperature outputs that we can no longer see the key signals that allow us to judge whether the models are physically correct. In other words the range of uncertainty dominates the signal.

The GCM models can reproduce the past climate because the inputs can be adjusted together to reproduce history but we can't validate whether the combination of inputs is just fortuitously right or represents a physically correct set of values.

I'm skeptical despite my usual doubts about the reliability of any large complex computer models because I find it incredible that we could have spent so much effort on GCMs without a fairly basic form of scientific validation.

So, are Pat Frank's claims remotely plausible? If not, why not? What validation has been done to make the inputs to GCMs physically plausible?

PS for those who are experts on climate science, try to avoid excessive jargon in your answers (or translate the jargon into language educated laypeople can understand.)

closed as primarily opinion-based by Sklivvz May 21 '15 at 23:13

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    I don't necessarily agree. "Useful" is usually understood to mean "useful for falsifying a hypothesis" in this context. I think that it is clear that they are claiming that the predictions from the models are "useless" in the sense that they cannot be falsified using plausible data. So there is a statistical meaning of "useless" which could be used to answer the question as asked. Roughly: can plausible data be used to falsify the predictions made by this model? – KAI May 21 '15 at 23:27
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    Useful for understanding what drives the earth's temperature. These are supposed to help drive our scientific understanding of climate by making meaningful forecasts. This is, surely, not a matter of opinion but a key scientific issue at the heart of modern climate science. Surely there are clear scientific ways to validate model utility. – matt_black May 21 '15 at 23:29
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    Your edit does not address the concerns I raised in any way, and made your answer more verbose and unclear, sorry. Find a single quotable claim and restrict it to one paragraph, for example. – Sklivvz May 23 '15 at 19:22
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    Further to my comment above. I've rolled back your edits because not only they did not improve the question, but they made it in a de facto blog post. Please use our site appropriately. – Sklivvz May 24 '15 at 1:02
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    See comments 4 and 5 for why your comment was removed. Avoid making this a personal discussion. The subject matter is this question. Further off topic remarks will be deleted without notice. – Sklivvz May 24 '15 at 13:12

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