Let the incredulity begin!

I have begun circulating the ‘Pot Lid’ essay in the blogosphere, and I find the early results very encouraging. Warwick Hughes (here) gave me a positive mention which has been very helpful in securing readers. I had exchanges in comments on the blogs of Judith Curry and Steve Easterbrook which were also helpful, even though my thesis met with intense opposition in both places.

It is clearly going to be a long journey to general acceptance. I knew this going in. Any new idea faces inertia and opposition, and the confusion now prevailing in climate science only makes the journey longer. I want to highlight something that happened on Steve Easterbrook’s blog, to illustrate just how hard it can be to secure agreement, even about something simple.

My thesis could if necessary be reduced down to three sentences.

1.  General circulation models are strictly hydrostatic, in that they forbid vertical motion of air (apart from non-prognostic parameterizations).

2.  Warming by CO2 necessarily involves permanent reshaping of the vertical air column, which cannot be reflected in a strictly hydrostatic model.

3.  This leads to errors that are large in comparison with the forecast warming.

That’s it. It’s almost like a compact syllogism. Models are hydrostatic, warming is not, therefore models of warming generate errors.

Steve Easterbrook (here) read my essay and pronounced it nonsense. He disputed my claim that models are hydrostatic(!). He urged me to read a textbook on modeling (I’ve been through about twenty of them so far) and to look up Arakawa-Schubert convective parameterization.

So I explained how Arakawa-Schubert parameterization doesn’t make the model any less hydrostatic, that the mass fluxes referred to there don’t change the mass assigned to each layer. Steve was indignant, replying in part: ‘Did you stop to wonder why the documentation would lay out in detail how the convective processes work, if they’re not actually used? Can you really be that stupid?’

Fred Moolten said something politer but similar on Judith Curry’s blog (here).

I would have been excited to argue about proposition 2), that warming leads to density shifts. And I would have been just ecstatic to argue about proposition 3), that without density shifts we get errors. But at this point we’re stuck arguing about proposition 1), whether models are even hydrostatic to begin with. I’ve also had a private e-mail exchange with a professional climatologist where so far I’m stuck at more or less that same point.

I am preparing a new version of the essay which contains a section explaining Arakawa-Schubert, just to speed the reader past this particular misconception. But I can see that it will be a while before this debate develops fully.


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