Disclaimer: although I'm one of the founding executive editors, I'm not speaking on their behalf.
GMD was set up about 5 years ago "to promote model development as a serious and worthwhile activity, by providing a home for papers covering a wide range of aspects of the subject." I previously blogged a little about it here on the occasion of it first being included in the ISI list.
We recently got our new impact factor, which now is a shade over 5 - an impressive value that places the journal a whisker behind the front-runner ACP in the EGU stable, and in the top 20 of all of the vast array of relevant geoscience-type journals (according to another ed who looked at the list - it seems broken at the moment). For context, GRL and Journal of Climate are about 4, the JGR family around 3. Basically, little beyond the tabloids and some review journals are more highly cited. Submissions are also still rising strongly. So clearly we were right, there was indeed a gap in the market and by any reasonable measure GMD has been wildly successful.
So we've changed it.
It had always been our hope that papers describing new models would be accompanied by the actual code. This would ensure persistence and traceability of models, and hopefully help to propagate good practice. But as a new journal (and one that was establishing an entirely novel niche) we didn't think we were in a position to require this. And while it was always encouraged, this wasn't enough in practice - only a very small number of authors actually provided the code. Now we are much better established and successful, and have decided it's time to take this step:
The paper must be accompanied by the code, or means of accessing the code, for the purpose of peer-review.Just to be clear, the reviewers are not required to review the code - this in some cases will be wholly impractical. Some models are massive, and/or tied to specific computer architectures. But the principle is clear. I'm hopeful that this requirement, together with a new mandatory section on wider code availability, should help the push towards open access.
There are various other more minor modifications (eg rationalisation of manuscript types) which we have made in light of what is now several years of experience. The full editorial is here, which also includes a link to the original proposal, as supplementary info.