Dear authors

Your paper has been seen by two expert reviewers, who in principle think the paper is publishable but also raise some very important points, which are seconded from my side from an editor's point of view. Many of those you have already adressed in your reply. The most important points of criticism that I see reading the reviews and which you should alleviate in any revised version are:

1. Both reviewers conclude that the changes that you made to the model have not solved the problem. It added another fitting parameter/degree of freedom, which made the results better for some sites but worse for others. The explicit conclusion of your paper therefore should be that the inclusion of a temperature dependent activation energy is not the final answer to the problem. However, also negative results are worth publishing as they clear the field for work in other directions.

In that respect, I realized that you did not do an independent parameter optimization for activation energies in the case when the dust/Ca effect is included. I would urge you to do this, as otherwise a robust conclusion on the dust/Ca effect cannot be drawn.

2. As editor of climate of the past I am a little concerned that the paper is quite technical and intended for the specialists in firn modeling and thus thematically would be more in the scope of The Cryosphere or a similar journal. My hope was that you could elaborate more on the implications of your work on climate reconstructions. However, given the fundamental criticism of the reviewers on the possible improvement of our understanding in firnification modeling (see point 1) any paleoclimatic conclusions would hinge on the caveats of the model. In case you submit a revised version to CP, I would nevertheless urge you to add some more discussion on the paleoclimatic implications of your work and the limitations of these conclusions.

In summary, any revised version of ther paper should include all your point-to-point changes in response to the reviewer comments as well as to my points above. Due to the fundamental criticism by the reviewers a revised version would have to go through another round of reviews.

Dear authors

Thank you for carefully revising your manuscript on "Modelling firn thickness evolution..." The revised version has now been seen by one of the previous reviewers and myself and I am happy to say that the manuscript has improved significantly. It has met many of the reviewer comments, although the reviewer still assesses the paper not as a breakthrough in this long standing problem in understanding firnification. Nevertheless, I deem it important to provide this information to the wider scientific public as it may shape future research.

Accordingly, I support publicaton of the manuscript after some further minor revisions. These pertain the following points:

- to warn the reader, please make clear in the abstract and manuscript early on that the changes done in the model do not provide a solution to the firnifaction issue at all sites.
- explain more carefully how you quantified the model parameters in Table 1 and 3
- rephrase the discussion of the physical processes as outlined by the external reviewer.
- please include the corrections and clarify the points raised in my annotated pdf attached to my editor comment

After including these corrections please provide me with a short point-to-point list of the changes you carried out.

All the best

Hubertus Fischer
(editor Climate of the Past)

Dear authors

thank you for carefully re-revising your manuscript, which is now ready for publication in CP.

All the best

Hubertus Fischer