Dear Mr. Kessler,

Three experts assessed your manuscript. They raised a number of concerns, which have mostly been addressed in your rebuttals.
I thus invite you to submit a revised version of your manuscript, which addresses the reviewer comments. In addition, all reviewers raised the issue of the processes leading to the significant loss of carbon at 125 ka, and I feel these processes need to be appropriately highlighted in your revised version. Enhanced Southern Ocean ventilation (is AABW stronger in your simulation?) as is seen in Fig.3 and in Fig.2 of AC3 would lead to a carbon loss from the deep ocean (and particularly the Pacific) (see for example Menviel et al. 2014 (Paleo), or Menviel et al., 2015 (gbc)). This loss is probably enhanced by the constant atmospheric CO2 forcing and the higher SST.
If you could please submit a pdf of your manuscript with tracked changes, that would be appreciated.

Looking forward receiving your revised manuscript,
Best regards,
Laurie Menviel

Dear Mr. Kessler and co-authors,

I have now assessed your revised version of the manuscript entitled “Ocean carbon inventory under warmer climate – the case of the Last Interglacial”, and your response to the Reviewers.
I am pleased to accept your manuscript for publication in “Climate of the Past” after minor revisions. Please find some comments below.

Best regards,
Laurie Menviel

Throughout the manuscript: Please replace all “in 125ka” by “at 125ka”

P1, last line: “due to changes”

P2, L.14: “with a persistent mid-depth Atlantic ventilation of northern sourced waters”. Could you please reformulate this? Do you mean that even if NADW transport varied across the LIG, there was always sustained NADW formation?

P4, L. 17: “two experiments”
P4, L. 17: “by about 32 PgC”

P6, L.16-17: “This impacts directly the mixed layer depth (MLD) by leaving new areas free from sea-ice allowing for air-sea exchanges”. Please reformulate that sentence as it does seem grammatically correct, and take out the “s” at the end of “exchange”

P7, L.11: “These changes”
P7, L.22: “compared to”
P7, L.24-26: I am not convinced by this sentence: the mixed layer depth is greater in austral winter in the Atlantic sector of the Southern Ocean at 125ka than at 115k. I would guess this leads to increased deep ocean convection, which would explain the lower ages in the Atlantic.

P7, l.28: “occur”

P8, L. 4-5: It is unclear to me what you really mean here. I don’t really see a poleward shift of SSW (which should form close to the Antarctic shelf) and I don’t understand what you want to say about the water coming from the subtropical gyre.

P8, L.30 to p9, L.3: Shouldn’t this be supported by showing ocean currents and their changes?

P9, L.5-6: Please remove: “where subantarctic waters upwell again.”

P9, L.7-8: I am really not sure this has been shown here. There is not enough information in the manuscript to clearly show that changes in productivity in each basin is due to changes in the ventilation of the Southern Ocean thermocline and not to changes in the strength of the upwelling in these areas (no information is given on winds or ocean currents).

P11, L.6: “At 115ka”

P12, L.10: “persists until 115ka”

P12, L. 28: Please note that, contrarily to your study, in Brovkin et al., (2016), the ocean carbon content decreases between 125 and 115 ka due to changes in shallow water carbonate precipitation (a process not included in your model, correct?).

P12, L.30-33: I think that these 2 sentences are not correct. Please note that in the simulations presented by Brovkin et al., 2016 , there is a global increase in land carbon due to peat accumulation (~32 PgC), while the vegetation loses carbon (~13 PgC).
As atmospheric CO2 only changes by a few ppm between 125 and 115ka, the increase in ocean carbon content simulated in your study should be compensated by ~300PgC loss of terrestrial carbon. It is thus hard to conclude that changes in ocean carbon are driving the atmospheric CO2 concentration.

P15, L.8-9: There is something wrong with that sentence, please reformulate.

Dear authors,

I have read your responses to the comments raised as well as the changes made to the manuscript. I am pleased to accept your manuscript for publication in “Climate of the Past” after technical corrections. Please find below some editorial comments below.

Best regards,
Laurie Menviel

Please note that in the following pages and lines refer to the “author response version 2” pdf, with changes highlighted.

1) Regarding EPC changes and their link to the upwelling. Thanks for providing maps of vertical transports and winds. Indeed the annual wind changes might be small, but it seems that the changes in vertical transport could impact EPC in the EEP and EEA… It is difficult for me to judge with what is available, but could you please check again. Please check your statement about changes in wind speed in Section 3.3. p8, as this does not seem fully consistent with the figures you provided.
2) In section 3.1., in the sentence you modified (L.4-5, p6): please add “an” before “increase”: “..and an increase in mixed layer depth…”
3) P8, L. 9: Since 125ka was before 115ka I would suggest to rephrase as:
“SSW boundary seems to be slightly poleward at 125ka (~60S) compared to 115ka (~58S).”
4) P13, Please modify the last sentence of the amended section as follows: “…the LIG in order to simulate a decrease in atmospheric CO2 content”