Global glacier volume projections under high-end  climate change scenarios

Shannon, Sarah; Smith, Robin; Wiltshire, Andy; Payne, Tony; Huss, Matthias; Betts, Richard; Caesar, John; Koutroulis, Aris; Jones, Darren; Harrison, Stephan

doi:https://doi.org/10.5194/tc-13-325-2019

Articles | Volume 13, issue 1

https://doi.org/10.5194/tc-13-325-2019

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

https://doi.org/10.5194/tc-13-325-2019

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

Articles | Volume 13, issue 1

Research article

|

01 Feb 2019

Research article |

| 01 Feb 2019

Global glacier volume projections under high-end climate change scenarios

Sarah Shannon, Robin Smith, Andy Wiltshire, Tony Payne, Matthias Huss, Richard Betts, John Caesar, Aris Koutroulis, Darren Jones, and Stephan Harrison

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Final revised paper (published on 01 Feb 2019)
Supplement to the final revised paper
Preprint (discussion started on 06 Mar 2018)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review', Ben Marzeion, 23 Apr 2018
- AC1: 'Response to Ben Marzeion's review', Sarah Shannon, 07 Sep 2018
RC2: 'Review', Anonymous Referee #2, 08 Jun 2018
- AC2: 'Response to Anonymous Referee #2', Sarah Shannon, 07 Sep 2018

Peer-review completion

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

AR by Sarah Shannon on behalf of the Authors (12 Sep 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Sep 2018) by Christian Beer

RR by Ben Marzeion (08 Oct 2018)

Suggestions for revision or reasons for rejection

I would like to thank the authors for the thoughtful, and in most cases, satisfactory responses to my review comments. In particular, I want to compliment them on performing a substantial amount of additional runs, including alternative optimization approaches. Those additional analyses and results make the manuscript a lot stronger and help to better understand and evaluate the results. I hope the authors would agree that there are still a number of issues with the model that will eventually need to be addressed, but given that this is a very new approach to modeling glaciers on the global scale (and one has to start somewhere), I think the comprehensive presentation of the validation results, and the discussion of the (in some cases problematic) model behavior warrants a publication in The Cryosphere.

There are just two minor comments that should be addressed prior to publication, and I have one suggestion that the author may consider for the further development of the model:
- My comment on P10 L1f does not seem to have been addressed.
- With my comment on Fig 6 and 7 (negative winter MBs and positive summer MBs) I did not want to imply that from a warm bias in winter follows a cold bias in summer (sorry for the confusion), but I wanted to suggest that it should be discussed why there are so many negative winter MB values (as well as quite a few positive summer MB values). Typically, winter and summer values are well separated by the zero line (see, e.g., Fig. 3 in Radic et al., 2014).

Finally, just an idea to consider, concerning the issue of water mass conservation being affected by the precipitation lapse rate (page 6, line 3): The authors correctly point out that a precipitation lapse rate is standard in glacier modeling (effectively increasing precipitation to the glacier surface compared to the data set used as boundary condition), and it makes sense because wind-blown snow and avalanching are important components of the mass balance of many glaciers – i.e., there is in fact horizontal redistribution of precipitation to the glaciers. One way to conserve mass would be to reduce the precipitation onto the non-glaciated area of the grid cell, which would be conceptually consistent with horizontal mass movement within the grid box.

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RR by Anonymous Referee #2 (12 Oct 2018)

ED: Publish subject to minor revisions (review by editor) (15 Oct 2018) by Christian Beer

AR by Sarah Shannon on behalf of the Authors (30 Nov 2018)

ED: Publish as is (13 Dec 2018) by Christian Beer

AR by Sarah Shannon on behalf of the Authors (18 Jan 2019)

Short summary

We present global glacier volume projections for the end of this century, under a range of high-end climate change scenarios, defined as exceeding 2 °C global average warming. The ice loss contribution to sea level rise for all glaciers excluding those on the peripheral of the Antarctic ice sheet is 215.2 ± 21.3 mm. Such large ice losses will have consequences for sea level rise and for water supply in glacier-fed river systems.