Equilibrium simulations of Marine Isotope Stage 3 climate

Guo, Chuncheng; Nisancioglu, Kerim H.; Bentsen, Mats; Bethke, Ingo; Zhang, Zhongshi

doi:https://doi.org/10.5194/cp-15-1133-2019

Articles | Volume 15, issue 3

https://doi.org/10.5194/cp-15-1133-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/cp-15-1133-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 3

Research article

|

26 Jun 2019

Research article |

| 26 Jun 2019

Equilibrium simulations of Marine Isotope Stage 3 climate

Chuncheng Guo, Kerim H. Nisancioglu, Mats Bentsen, Ingo Bethke, and Zhongshi Zhang

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Final revised paper (published on 26 Jun 2019)
Supplement to the final revised paper
Preprint (discussion started on 03 Dec 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of Guo et al: Equilibrium simulations of Marine Isotope Stage 3 climate', Anonymous Referee #1, 13 Dec 2018
- AC1: 'response to comments by Anonymous Referee #1', Chuncheng Guo, 26 Feb 2019
RC2: 'Equilibrium simulations of Marine Isotope Stage 3 climate by Guo et al. - a review:', Anonymous Referee #2, 10 Jan 2019
- AC2: 'response to comments by Anonymous Referee #2', Chuncheng Guo, 26 Feb 2019
RC3: 'review comments', Anonymous Referee #3, 14 Jan 2019
- AC3: 'response to comments by Anonymous Referee #3', Chuncheng Guo, 26 Feb 2019
RC4: 'Review of Guo et al "Equilibrium simulations of Marine Isotope Stage 3 Climate"', Anonymous Referee #4, 16 Jan 2019
- AC4: 'response to comments by Anonymous Referee #4', Chuncheng Guo, 26 Feb 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (27 Feb 2019) by Laurie Menviel

AR by Chuncheng Guo on behalf of the Authors (10 Apr 2019) Manuscript

ED: Referee Nomination & Report Request started (22 Apr 2019) by Laurie Menviel

RR by Anonymous Referee #2 (16 May 2019)

RR by Anonymous Referee #1 (16 May 2019)

Suggestions for revision or reasons for rejection

The manuscript by Guo and colleagues has greatly improved after the first round of reviews. The new insights provided by the study and its place in the context of previous MIS3 studies comes out much more clearly. The discussion of the AMOC response has also become more clear.
I recommend to accept the manuscript subject to a few minor revisions which I list below:

1. The PI simulation should also be introduced in Section 2.2. If the PI simulation is the same as the simulation in the Guo et al (2019, GMD) paper, then this should at least be mentioned - either in section 2.1 or towards the end of section 2.2, when the PI simulation is first referred to.

2. (p.7, ll-14-18) It would be nice to have some conclusion from the comparison of LGM and MIS3 surface temperatures. Is the result of the comparison reasonable given the differences and similarities between MIS3 and LGM?

3. (p.6, ll.30-31) When describing the spin-up of the AMOC in section 3.1, you say that the final difference in AMOC strength is 1.9Sv. But this difference at 26N appears to be an underestimation of the total difference, as the difference in max. AMOC strength seems to be 3.2 ( p.9, l.17). This should at least be mentioned.

4. Two sections have been moved completely into the supplementary material (precipitation on p.8 and modes of variability on p.11). This is very beneficial for the overall length and readability of the manuscript. But I would suggest that at least one or two sentences should be included in the manuscript to summarise the main findings of the sections that have been moved. To have only the reference to the existence of the extra sections without connecting them to main text seems a bit odd. It raises the question whether they are needed at all.

5. (p.10, ll.24-25) It is not immediately clear to me, how the stronger northerly winds lead to less sea ice in the western Labrador Sea.

6. (p.11, ll.27-29) An additional factor could be the active deep water formation in the Nordic Seas in the MIS3 simulation. Under LGM conditions I would expect the Nordic Seas to be completely ice covered with little deep convection there. This could also contribute to the different AMOC state.

7. (p.14, ll.23-24) Add a reference to Figure S6 here.

I look forward to seeing the manuscript in its final and published form!

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ED: Publish subject to minor revisions (review by editor) (18 May 2019) by Laurie Menviel

AR by Chuncheng Guo on behalf of the Authors (28 May 2019) Author's response Manuscript

ED: Publish subject to technical corrections (04 Jun 2019) by Laurie Menviel

Dear Dr. Guo,

I have read your response to the Reviewers’ comments as well as the revised version of your manuscript. As appropriate changes have been made into your manuscript, I am pleased to accept it for publication in Climate of the Past. Please find below a few minor comments to include in your final version.
Looking forward seeing your manuscript published.

Best regards,
Laurie

Final comments Guo et al.

P2, L. 27: “a coupled model of intermediate complexity (Van Meerbeeck et al., 2009)”
For consistency you should also include Menviel et al., 2014 there.

P5, L. 13: Please correctly format “(MANGERUD et al., 1998..”

P6, L.35: Please remove “the” in front of AABW.

P7, L. 19-20: This sentence would need to be reformulated, maybe:
“The simulated cooling during MIS3 is not as intense as the one suggested for the LGM, because the continental ice-sheets used as forcing are smaller and the atmospheric CO2 concentration is greater than the LGM one.”

P8, L. 9: “The reduced atmospheric CO2 concentration…”

P11, L. 9: Please add a capital letter to “We”. The “Mode of variability” section is now very short. I wonder if it would not make more sense to move this whole paragraph to p8, L.7. in the atmospheric section (therefore also taking out the “Mode of variability” title).

P11, L. 15: “during MIS3”

P11, L. 26: I don’t think this is correct “The simulated ventilation of AABW..” maybe rephrase as “The simulated AABW transport…”

Figure 9: I am a bit surprised by the amount of “white shading” included within the dashed black lines. Maybe this is simply due to the color scheme used between 0 and 1 m of sea-ice. I suppose the 0.1m contour should more or less corresponds to the 0.15% contour, correct? Please make sure the position of the dashed lines and the shading levels are correct.

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AR by Chuncheng Guo on behalf of the Authors (05 Jun 2019) Manuscript

Short summary

We present an equilibrium simulation of the climate of Marine Isotope Stage 3, with an IPCC-class model with a relatively high model resolution and a long integration. The simulated climate resembles a warm interstadial state, as indicated by reconstructions of Greenland temperature, sea ice extent, and AMOC. Sensitivity experiments to changes in atmospheric CO₂ levels and ice sheet size show that the model is in a relatively stable climate state without multiple equilibria.