Review of « A continuous 6000 year age depth relationship for the remainder of the Weißseespitze summit glacier based on 39Ar and 14C dating” by Wachs et al., submitted to CP, 2025.

This manuscript presents an innovative method of combining radiogenic dating methods using 14C (previously published) and 39Ar on a set of ice cores extracted between 2019 and 2024 from the Weißseespitze summit glacier. These dating points are then compiled and used to feed different dating models in order to evaluate them, obtain annual accumulation values and estimate the age of the surface ice.

I recommend this manuscript for publication, after some major revision.

General comments:

Although this combination of the two radiogenic methods has already been presented on other sites (Tibet, Dôme du Goûter), its use on an ablating glacier, having lost 80% of its thickness compared with its maximum extension, is particularly ambitious and interesting since these cases will unfortunately occur more and more often.

This study required the compilation of glaciological data and the use of statistical methods that went beyond the application of the dating methods mainly presented, and the rigorous presentation of the limits of these compilations, clearly highlighting the uncertainties in the data and methods used.

However, some aspects need corrections or adjustments:

1) The authors maintain that the data presented allow us to assert that there is no hiatus over the upper 2000 years of the profile. In Figure 4b, the zoom on the dated points, this conclusion is not obvious. In my opinion, between the 39Ar and 14C point series, it seems to me that these two series are not as well 'aligned', despite the uncertainty bars. This could possibly be due to a hiatus during this time interval, or as proposed that the 39Ar dates are inaccurate due to the half-life value not being updated.

2) The authors conclude that the combination of 39Ar and 14C has provided a significant advance in dating by allowing a better fit of the best dating model. For this conclusion, it would have been interesting to be able to judge this by presenting the best model fit using only the 14C and glaciological data, then a new version adding the 39Ar dating points, even if a short test (line 305-309) tries to convince us.

3) On these summit glacier sites, Weißseespitze, Colle Gnifetti or Dôme du Goûter, the net accumulations are not representative of precipitation because a major part of the winter and/or annual snow is blown away. This is one of the reasons why these sites are unique and have preserved fairly old ice, which is interesting for certain studies. On the other hand, this means that the annual record is not complete (often only wet summer snow is accumulated). Under these conditions, the comparison of chemical profiles, where the aim is to identify specific events and compare them with other sites, is questionable. The dust layers may have different sources, Saharan dust, or a longer period of local dust deposition following a period of ablation. In this manuscript, I propose to delete the paragraph concerning the Calcium profile and their comparison with Colle Gnifetti.

4) With regard to the accumulation values obtained by the models, it is clear that these have not been constant over this long 6000 years period. First of all, the values obtained with the 6 high points and then the 6 low points are quite different. Can you either expand on your conclusions, or use a model that allows accumulation to evolve over time?

Special remarks:

- Lines 24-25: "novel combination" is not correct, it has been used and published previously (Tibet, Dôme du Goûter).

- Line 45: add significant references to Alpine Holocene records.

- Lines 74-75: add information on temperatures, figures or data.

- Line 76: "is rapidly declining", add data

- Line 97-100: If the glacier is covered by a homogeneous layer of dust on the surface, this does not necessarily mean that it comes from a deep layer that appeared following the melting of the surface, but it may come from deposits of recent particles accumulated over the entire ablation period, just hidden during the winter but returning the following spring.

- Line 125: Illustrating the 3H profile in Figure 3 could complement the data presented.

- Line 179: Why has a 14C value been removed?

- Line 305-308: Do the 6 upper dots represent 39Ar, and the 6 lower dots 14C?

- Line 318-328: Should the new estimate of the half-life of 39Ar not be used, or at least compared with the current value, in this work?

- Line 339-364: The discussion of calcium profiles is not convincing.