The GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 1: Projections of the Greenland ice sheet evolution by the end of the 21st century

Quiquet, Aurélien; Dumas, Christophe

doi:https://doi.org/10.5194/tc-15-1015-2021

Articles | Volume 15, issue 2

https://doi.org/10.5194/tc-15-1015-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

The Ice Sheet Model Intercomparison Project for CMIP6...

https://doi.org/10.5194/tc-15-1015-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 2

Research article

|

26 Feb 2021

Research article |

| 26 Feb 2021

The GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 1: Projections of the Greenland ice sheet evolution by the end of the 21st century

Aurélien Quiquet and Christophe Dumas

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Final revised paper (published on 26 Feb 2021)
Preprint (discussion started on 02 Jun 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'The GRISLI-LSCE contribution to ISMIP6, Part 1: projections of the Greenland ice sheet evolution by the end of the 21st century', Anonymous Referee #1, 30 Jun 2020
- AC1: 'Response', Aurélien Quiquet, 20 Oct 2020
RC2: 'Review of Quiquet and Dumas, "The GRISLI-LSCE contribution to ISMIP6, Part 1: projections of the Greenland ice sheet evolution by the end of the 21st century"', Anonymous Referee #2, 16 Jul 2020
- AC2: 'Response', Aurélien Quiquet, 20 Oct 2020

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (13 Nov 2020) by Ayako Abe-Ouchi

AR by Aurélien Quiquet on behalf of the Authors (13 Nov 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (23 Nov 2020) by Ayako Abe-Ouchi

RR by Anonymous Referee #2 (07 Dec 2020)

Suggestions for revision or reasons for rejection

Overall, I think that the authors have done a reasonably good job revising the paper, and I only have some remaining issues.

Most importantly, I take it from the authors' reply that they have not followed my suggestion that "the entire manuscript should be very carefully proofread by a (near-) native speaker or a professional language editing service." As a result, there are still a considerable number of language issues, especially in the newly written parts. I am aware that, as the authors write, "The Cryosphere journal includes a language editing service for all accepted manuscripts". However, in my understanding, this service must not serve as an excuse for taking a relaxed stance on the quality of the writing. Just being "generally understandable" is not sufficient! Rather, authors of papers in high-quality journals like The Cryosphere should make every effort to deliver their contributions in a near-perfect condition.

Below, I will suggest some corrections (the majority of all comments). However, I neither have the time nor the motivation to proofread the entire manuscript carefully (especially because I'm a non-native speaker either...), so that these corrections have no claim for completeness.

Page/line numbers refer to the diff version of the manuscript that came attached to the response letter.

P. 2, l. 28:
"(CMIP6 forcing, separate effects of the atmospheric and oceanic forcings)"

P. 3, l. 26: "ice sheet model_s_"

P. 3, l. 26:
This sounds as if the flow enhancement factor favours only selected deformation modes., which is wrong. Rather "factor that increases the ice fluidity in the SIA".

P. 4, l. 9: "consists _of_ finding"

P. 4, l. 27: "Greenland_'s_ floating ice tongues, _the_ sub-shelf melting rate"

P. 5, l. 5: Delete "in the atmospheric model"

P. 7, l. 12: Unit of "about 0.55"? Log of velocities in m yr-1, I suppose?

P. 7, l. 18: "the _south-eastern_ glaciers"

P. 7, l. 19: "small_,_ meaning"

P. 8, l. 14:
"sharp inflexion" sounds strange either. What about "we can not discern any sudden change ... century that may indicate a tipping point".

P. 8, l. 16: "forcing_s_"

P. 8, l. 16: "mass balance _becoming_ negative"

P. 8, l. 17: "2060_,_ while"

P. 8, l. 23: "_the_ SSP585 scenario"

P. 8, l. 26:
The authors may consider comparing their findings re CMIP5 vs. CMIP6 to those described in Sect. 4.2 of the Technical Report by Greve et al. (2020, Zenodo, https://doi.org/10.5281/zenodo.3971251).

P. 8, l. 32: "mass loss _compared_ to the"

P. 9, l. 1: "_compared_ to the"

P. 10, l. 3: "of the _combined_ forcing"

P. 10, l. 15: "integrated _divergence of the ice flux_ can be"

P. 10, l. 21: Delete "(ice flux convergence)" [unnecessary duplication]

P. 10, l. 22: Delete "(ice flux convergence)"

P. 10, l. 26: "change_,_ we show"

P. 10, l. 27: "values_,_ suggesting"

P. 11, l. 5: "south-eastern and central western regions"

P. 11, l. 27: "_for_ the control experiment"

P. 12, l. 3: "optimally tune_s_"

P. 12, l. 4: "with _the_ present-day"

P. 12, l. 6: "by construction, our simulations"

P. 12, l. 7-9: 6.5 cm is not "large" compared to 3.5-14 cm. Rather "it is comparable to the spread"?

P. 12, l. 10: "largest source_s_ of uncertainty"

P. 12, l. 11: "_an_ ice sheet at equilibrium"

P. 12, l. 19: Not only diffusion. Except for the near-basal parts of an ice sheet, downward advection is actually more efficient. Perhaps more generally "since the information|memory of the low temperatures of the glacial period in the ice sheet"?

P. 12, l. 31: "ISMIP6-Greenland _accounts_ for the vertical"

P. 12, l. 34: "under _the_ RCP8.5 scenario"

P. 13, l. 1: "smaller compared to"

P. 13, l. 2: "respectively)_,_"

P. 13, l. 3: "smaller _than that of_ Vizcaino"

P. 20, Fig. 2, caption: "_with respect to_ the end"

P. 21, Fig. 3, caption: "for _the_ velocity difference_s_"

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RR by Anonymous Referee #1 (31 Dec 2020)

Suggestions for revision or reasons for rejection

I thank the authors for their thoughtful consideration of the comments and the improvements they propose to make to the paper. I appreciate the perspective they have added in the introduction, and the clarification of the decomposition into SMB and dynamic contributions. I have a few more comments on their new draft which they may wish to consider.

page 1 line 16-17. "and is now larger than"

page 4 line 6. If I've understood this correctly, you call them "iterations" because you do them sequentially. "Iteration" usually has the idea of repeating the procedure but starting from where the previous iteration ended, whereas your "iterations" all start from the same state. Therefore I find "iteration" slightly misleading. You could call them an ensemble, except that you also use the final state to modify the next "iteration". Perhaps it would be better to call them something like "short transient experiments", which distinguishes them from the long equilibrium experiments.

page 6 line 16. "Instead" doesn't sound quite right to me. You don't mean a replacement, but a comparison. I would say, "On the other hand" or "By contrast".

page 8 line 19. I don't think it's correct that "CMIP6 models show generally a much larger" climate sensitivity than CMIP5. There are certainly some models which a considerable larger sensitivity, but the ranges given on the following lines for ISMIP6 are not representative of CMIP6 in general.

page 8 lines 20-21. Units of climate sensitivity are K.

page 10 line 27. I think you mean it's the same range of colors, don't you? I would not say it's the same color scale; it's an order of magnitude different, which is the point you are making, if I understand correctly.

page 11 line 9. I would say "inaccurate" rather than "unjustified", which is unfair to yourselves. It was a justifiable choice, on grounds of simplicity.

Fig 11. It would be helpful if you could put a % change on the right-hand axis of these figures.

page 12 line 2-15. This point seems important to me and perhaps deserves to be mentioned in the conclusions and maybe the abstract.

page 12 line 5. loosing -> losing (you can't be blamed for surprising English spellings)

page 13 line 18. looses -> loses (same comment)

page 13 line 17-27. As I commented last time, I think you could draw attention in the conclusions to some more of the findings from the large range of experiments you are able to carry out (as well as adding the point of the first paragraph of page 12). You could state more clearly that the dynamical contribution is generally much smaller (by an order of magnitude) than the SMB contribution (which is implied by the final sentence of the conclusions, but clearer earlier in the text), that consequently the uncertainty in ocean forcing has a relatively small effect on the spread of projections, which mostly comes from the SMB, and that the basal drag is rather poorly constrained but doesn't much affect the projections to 2100. Perhaps some of these might be added in the abstract too.

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ED: Publish subject to minor revisions (review by editor) (03 Jan 2021) by Ayako Abe-Ouchi

AR by Aurélien Quiquet on behalf of the Authors (13 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (18 Jan 2021) by Ayako Abe-Ouchi

AR by Aurélien Quiquet on behalf of the Authors (23 Jan 2021) Author's response Manuscript

Short summary

We present here the GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for CMIP6 for Greenland. The project aims to quantify the ice sheet contribution to global sea level rise for the next century. We show an important spread in the simulated Greenland ice loss in the future depending on the climate forcing used. Mass loss is primarily driven by atmospheric warming, while oceanic forcing contributes to a relatively smaller uncertainty in our simulations.