|The authors have addressed most of my comments and the overall structure is now easier to follow. However, it could still use a few changes to improve clarity, especially in the Discussion session. See below some suggestions on this and other minor points. |
Note that pages and line numbers refer to the track-changes version of the manuscript.
Abstract: remove the last statement “on which we include a detailed discussion” as it is unnecessary here.
Page 5, lines 30-31: it would be appropriate to cite at least one earlier reference and especially one that is based on the analysis of the sedimentary record, rather than only numerical simulations - e.g. Kohfeld et al. (2005)
Kohfeld, K.E., Le Quéré, C., Harrison, S.P. and Anderson, R.F., 2005. Role of marine biology in glacial-interglacial CO2 cycles. Science, 308(5718), pp.74-78.
Page 7, line 20: I still don’t find “theoretical approach” the right definition here and a somewhat confusing way to call this. These are “offline calculations of the biological pump efficiency” or something along these lines.
Page 7, lines 30-32: this sentence is a little long. Break up or at least add a comma between “mechanisms” and “obtained”.
Page 8, line 1: figure should be sequential, but here you reference figure 7. But this is probably fine if you at least state that this figure is in Appendix A (here and everywhere else in the text afterward).
That said, I am not sure that you need both a Supplementary Material and an Appendix?
Page 11, line 12: I just find this reference to a “theoretical framework” unnecessarily confusing again here. All you need to say really is something like: […] and discuss the LGM-PI changes by exploring the efficiency of the biological pump (Sect. 3.3).
Similarly in other parts of the text, as noted before.
Page 9, Line 28: “weaker” rather than “slower”.
Page 10, line 3: the meaning of the first part of the sentence (“Besides radiocarbon aging of in particular SSW”) is unclear, so please rephrase.
I think that supplementary Figure S2 is useful, but it doesn’t seem to be referenced anywhere in the text.
Page 15, line 7: as well as
Page 14 onwards: the current “Discussion” session (4) is clearer as a self-standing section, but a little heavy as it is and could use some breaking up into subsections from line 15 onwards.
I would suggest, for instance, renaming the whole section something like “LGM model-data biases” and add a couple more subsections to break this up a little. So the current subsection 4.2 could keep the same title but become 4.4 and before that the physical/water mass changes could be highlighted in one subsection (4.1) and then separate the biological mechanisms and DIC discussion from page 15 line 8 (4.2).
Or split it in a different way if you think it is more appropriate, but add at least two additional break points here.
I am saying this because this discussion is interesting and useful in highlighting several important results from these simulations, but it is hard to follow and the reader would struggle with it as is.
Page 18, line 5 onwards: it may be useful to refer to, as another example, this newly accepted paper: Zhu et al. (2021), GRL, Assessment of equilibrium climate sensitivity of the Community Earth System Model version 2 through simulation of the Last Glacial Maximum. Where the LGM simulation is used to show biases that would also affect simulations used for future projections with the same model (even though the focus is on equilibrium climate sensitivity and cloud feedbacks).