As so much blood sweat and tears has gone into attempts to get access to the data sets numerous climate scientists have been working on (CRU etc), leading to some of the most adversarial confrontations between mainstream climate scientists and sceptics, is it time to start making a concerted push for open access to the models?

Access to the source code of most of the models appears to be patchy at best and I'm curious as to why there hasn't been a greater drive to make it publicly available. Most of us have our doubts about the outputs, why don't we go to the source? And why aren't most of the models public domain already?

Katabasis, first off, I'm not even close to a professional programmer. But when a grad student, I did occasionally use (or tried to make use of) free scientific software as developed by academics and made 'freely available' (and probably in the genuine spirit of the phrase) for specific technical purposes.

I found it, almost without exception, impenetrable. Unusable. Close to zero documentation. Not worth the effort. Even as someone who roughly understood what it was supposed to do, and how it was supposed to do it. And these had relatively few input/output parameters. To this, maybe only averagely-competent user (or worse), Microsoft or any other reviled corporation seemed to produce software that was incomparably more user friendly. (But they didn't make software to do what I needed. Why would they?). I doubt if this was exceptional, or if anything has changed.

This is not really surprising because 'academic' software is most likely going to be most important to, and only easily understood by, the people who wrote it. They have no great incentive to make it otherwise, and won't have time/resources/inclination to devote to "customer support." Especially if the "customer" is not able to contribute something in return.

I think I may have read that at least some of it is available. Or at least so it can be claimed, in the full knowledge that it is not likely to be of any practical value to you by itself. [And in a parallel universe some of the same people will probably say they would happily give Steve McIntyre free access to their data.]

Unless you already work in the field, and are on friendly terms with those who produce/use the programs then, well, good luck....

If you write a program for a bank, or an airline booking system, you would (I suppose) have to write it professionally, with testable (and tested) modules, and comments that explained how it worked. Then (when you went to another job) those using the program could update it and correct problems when these arose.
If it is the case that climate computer models are not written to the same standards, so that they are opaque to anyone other than the program writer (and probably even to him or her, when returning to them later) on what basis can we put any reliance on them? If the programs are uncheckable, they're unacceptable.