The importance of snow albedo for ice sheet evolution over the last glacial cycle

Willeit, Matteo; Ganopolski, Andrey

doi:https://doi.org/10.5194/cp-14-697-2018

Articles | Volume 14, issue 5

https://doi.org/10.5194/cp-14-697-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/cp-14-697-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 5

Research article

|

31 May 2018

Research article |

| 31 May 2018

The importance of snow albedo for ice sheet evolution over the last glacial cycle

Matteo Willeit and Andrey Ganopolski

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Final revised paper (published on 31 May 2018)
Preprint (discussion started on 17 Oct 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review of Willeit et al.', Anonymous Referee #1, 01 Dec 2017
- AC1: 'Response to referee #1', Matteo Willeit, 12 Feb 2018
RC2: 'Review of Willeit and Ganopolski.', Jorge Alvarez-Solas, 08 Jan 2018
- AC2: 'response to the review by Jorge Alvarez-Solas', Matteo Willeit, 12 Feb 2018

Peer-review completion

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

ED: Reconsider after major revisions (16 Feb 2018) by David Thornalley

AR by Matteo Willeit on behalf of the Authors (26 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (04 Apr 2018) by David Thornalley

RR by Anonymous Referee #1 (30 Apr 2018)

Suggestions for revision or reasons for rejection

The authors have put some efforts in better described their model, which is much appreciated. I also thank the authors for their discussion on the validation of the parametrisation with offline experiments. Unfortunately, they deliberately ignore the suggested additional sensitivity experiments. The authors state in their response that “right results can be obtained for the wrong reason”. I perfectly agree with this and I can also add the famous quote “all models are wrong but some are useful”. Even the most sophisticated GCM will miss important processes or feedback and might get the “right results” for the “wrong reason”. This is because we have uncertainties in climate models that sensitivity studies are so important. As mentioned in my first review, I do agree that dust deposition and aging are important processes for ice sheet evolution but I still have doubts about the experiments you show to highlight this. In my first review I did not suggest that you “explore the whole range parameter space” but I suggested a few simple sensitivity experiments that could bring, to my opinion, valuable pieces of information. I suggested to ignore separately the role of dust deposition and aging with a slightly different snow albedo reference value. The idea behind this was to show the importance of these processes on the climatic trajectory followed by the model. This would have strengthened the paper and it is a pity that the authors chose not to show such experiments. As it stands I still think that the experiments shown (ON/OFF) are oversimplified and does not bring much of additional knowledge.

A side note: there is a discrepancy between the authors’ response to reviewers that appear on the publicly visible discussion forum and the private reviewer section. In particular, the maps and the associated discussion related to the validation of the scheme (P.3 of the private response to reviewers) is missing in the public discussion forum. There is also a disagreement in the two files when replying about refreezing. I think this is important to have the two files consistent by replacing the public version with the more thorough private one.

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ED: Publish subject to technical corrections (14 May 2018) by David Thornalley

AR by Matteo Willeit on behalf of the Authors (15 May 2018) Manuscript

Short summary

The surface energy and mass balance of ice sheets strongly depends on surface albedo. Here, using an Earth system model of intermediate complexity, we explore the role played by surface albedo for the simulation of glacial cycles. We show that the evolution of the Northern Hemisphere ice sheets over the last glacial cycle is very sensitive to the parameterization of snow grain size and the effect of dust deposition on snow albedo.