Articles | Volume 21, issue 5
https://doi.org/10.5194/os-21-2283-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.Contribution of meridional overturning circulation and sea ice changes to large-scale temperature asymmetries in CMIP6 overshoot scenarios
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- Final revised paper (published on 07 Oct 2025)
- Preprint (discussion started on 25 Apr 2025)
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
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RC1: 'Comment on egusphere-2025-1784', Anonymous Referee #1, 09 Jun 2025
- AC1: 'Reply on RC1', Pedro Roldán, 17 Jul 2025
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RC2: 'Comment on egusphere-2025-1784', Anonymous Referee #2, 16 Jun 2025
- AC1: 'Reply on RC1', Pedro Roldán, 17 Jul 2025
- EC1: 'Comment on egusphere-2025-1784', Meric Srokosz, 23 Jun 2025
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Pedro Roldán on behalf of the Authors (17 Jul 2025)
Author's response
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ED: Referee Nomination & Report Request started (21 Jul 2025) by Meric Srokosz
RR by Anonymous Referee #2 (12 Aug 2025)

RR by Shouwei Li (26 Aug 2025)

ED: Publish subject to minor revisions (review by editor) (26 Aug 2025) by Meric Srokosz

AR by Pedro Roldán on behalf of the Authors (29 Aug 2025)
Author's response
Author's tracked changes
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ED: Publish as is (02 Sep 2025) by Meric Srokosz

AR by Pedro Roldán on behalf of the Authors (02 Sep 2025)
Review of ‘Contribution of meridional overturning circulation and sea -ice changes ot large-scale temperature asymmetries in CMIP6 overshoot scenarios’. By Roldán-Gómez
An analysis is conducted three different overshoot scenarios from 13 different coupled models. The focus is determining the spatial patterns of SST anomalies that emerge in the overshoot period. They find different spatial patterns emerge depending on whether there are large changes in the AMOC or sea-ice. The AMOC influence is greater when there is a larger reduction in NA mixed layer. This happens when the models have a larger climatological MLD to start with. These findings are in the main well-reasoned and the work should make a useful contribution to the literature. It is noted that the paper represents a considerable amount of analysis across multiple models to reach these conclusions. Indeed, aside of minor specific comments, my main general comment is that the authors need to make a greater effort to distil the research (and in particularly the number of figure panels) into that which is necessary to reach these conclusions.
General Comments
A greater effort should be made to distil the research into that which is necessary to convince the reader of their conclusions. In particular, there is an overabundance of figures.
Although only 15 figures, this is made up of over 140 figure panels. I would encourage the authors to aggressively cull this number. There are a number of ways to evaluate if they are all necessary. Some of the plots contain linear regression, many of these could be probably best summarized by a table of the correlation values (and if they are significant or not). Furthermore, the authors may want to consider if they need to include results from all the scenarios. In particularly do the additional insights obtained from SSP1-1.9 warrant its inclusion.
Further Points
Abstract
Line 8: In the abstract. Candidate mechanisms are listed: ‘Changes in the sea ice, changes in the ocean circulation and heat transport, and thermal inertia of the ocean have been identified as potential sources of hysteresis ‘. It would be helpful when listing these to enumerate these and when listing them elsewhere in the manuscript, to use consistent terminology. (For example, later in the manuscript ‘AMOC’ is used rather than ‘ocean circulation and heat transport ‘ ). This will help the reader relate the analysis in the manuscript with the abstract. For example, the term ‘Thermal inertia’ is not mentioned in the manuscript beyond the introduction.
Line 30. A figure illustrating the time series of CO2 concentration in two scenarios, would help the initiated.
Line 65. In light of the range of processes mentioned in the existing literature (line 40-44) why have the authors decided to focus on the “ocean dynamics and sea-ice changes”?
Methods
What is guiding the choice of simulations? Is it just everything available? The authors may consider if the inclusion of SP1-1.9 adds significantly to the work.
Line 93. Could the authors state here how the post peak period is defined.
Line 110. As before, please clarify the reason for the choice of mechanisms investigated.
Figures 2ab, 3, 5, 6, and 7. These figures are quite complicated. Could the authors provide a bit primer, so the readers can clearly identify the key points from them.
Line 121. ‘After the stabilization’. Stabilization of what. Could the authors refer to specific years.
Line 122. ‘Larger than expected’. It is not clear what is expected. Please state the years that are being referred to, what specifically is it larger than (and how much).
Line 150. MRI shows a 2.0 C EN-ES asymmetry at year 2200 for SSP5-4.4OS (Figure 3a). However, for SSP1.-19, the maximum asymmetry is only about 0.6C at about 2040 (Figure 3b)”. Unless I fail to understand the figure.
Line 150 ‘Strong’. Please define ‘strong’ in turns of magnitude and state the time at which this can be seen in the relevant figure.
3.1 Line 150-156. What does the variety in the results reveal?
Line 173. SO higher mean values of OHT are found in SSP5-3.4OS-ALL (middle panel) but not SSP5-3.4OS EXT (left) or SSP1-1.9 ALL (right)
Line 175. ‘Some models like MRI-ES2.0’. The wording of this sentence is a little strange as figure Fig. 5 abcd show that MRI-ES2 is an outlier, i.e. there are no other models like it.
Line 177. ’moderate strengthening of OHT in SO in Fig 5ef’. Could the authors specify the post-overshoot years in which OHT is moderately strengthened.
Line 180. MLD Fig 5e. IPSL is strong outlier in terms of WS MLD. For SSP5-340S, it looks like the change in the other models is not so significant.
Fig. 8. It is difficult to see difference between dotted and solid line, please thicken the solid line or strengthen the difference in some other way. Probably no need for AMOC vs OHT, the relationship is well established.
Line 199. Suggest ‘Figure 8e and f) shows…’. The description of Figure 8 is not quite correct. EN-ES is only related to OHT. AMOC and MLD are related to OHT not to EN-ES SST. It might be more useful to have EN-ES vs OHT and EN-ES vs MLD.
Fig 8f) What is the physical explanation for the lack of correlation between EN-ES SST and OHT in SSP1.1.9?
There is no reference in text to Figure 9 c through f). I suggest these panels are removed.
Line 215. ‘The contribution of sea ice change seems more important’. Don’t the dashed lines in Figure 10 indicate the contribution of sea-ice change is insignificant? I suggest the references to the influence of sea-ice are removed.
Line 226: ‘Unlike for the ENM-ENH asymmetry, the contribution of sea ice changes to the SSW-SSE asymmetry (Fig. 11i,j) seems marginal’. Or like the ENM-ENH asymmetry it seems insignificant. If the authors do not wish to attach any importance to the significance test, they should probably explain why. The authors might consider if Figs, 10 and 11 are necessary.