Dear authors,

I largely agree with the both reviewers. This is an important contribution to document coastal changes for the past decades, and this part itself has a large value. I urge the authors to consider releasing the dataset when the manuscript is accepted and mention data availability in the revised manuscript. The both reviewers concern the interpretations of documented changes in terms of environmental factors. I am happy to see that the authors plan to follow their advice. Although I don’t have specific suggestions except for a few points listed below, careful re-wording is crucial in this revision stage to be considered as a possible publication in TC.

1. I am not convinced with author’s response to the point on threshold and non-linear nature in ice-shelf dynamics. Even if spatial relationship, rather than temporal changes, is examined, it is still hard to identify “driving factors” simply by correlations. Reviewer #2 used careful wording, “diagnosis through correlation”. Limitations of this diagnosis should be clarified to avoid misleading.

2. Both reviewers emphasized the importance of extreme, short-term events, which the authors agreed. Please make sure that the revised manuscript presents presence and possible consequences of extreme events, though no additional analysis is necessary.

3. Please include statements on the analysis buffer of 100 km or of 200 m elevation difference in the revised manuscript.

I look forward seeing the revised manuscript with careful wording and clarifications.

Kenny Matsuoka
TC/TCD Editor

Dear authors,

Your original manuscript was reviewed by two referees, and the revised one was reviewed by one referee. These referees and I concerned to identify driving forces from regional correspondences between coastline migration and environmental factors. You made excellent work to address our concerns. This point is no longer my concern. Also, clarify and readability of the manuscript were largely improved. So, first of all, I would like to thank authors’ effort in this revision process.

I have several more concerns, and many editorial suggestions. The referee also provided very thoughtful comments in pdf; these are mostly editorial, but suggest local restructuring from sentences to a paragraph level at several locations. Therefore, I request a minor revision. Please provide the track-change manuscript and a response letter when you submit the revised manuscript. No responses are necessary for purely editorial issues, but I would like to see responses to following relatively major issues. In the comments below, all page and line numbers refer the track-change manuscript.

1. I am somewhat confused with “ice shelf and glacier front” that appears so many times in the manuscript. P2L31 refers Nicholls et al. (2009) and says “ice shelves and glaciers are the floating extensions of the ice sheet”. I cannot find this definition in that reference; if I am right, please delete this sentence/reference. Also, in my opinion, this definition is wrong. The glaciers are grounded. The term “glacier tongues” are sometimes used to refer fast-flowing part of an ice shelf that is fed by a fast-flowing glacier. However, for your work, I don’t see a specific need to distinguish glacier tongues and other ice shelves. About one quarter of Antarctic coastline has no ice shelves and the ice sheet is terminated with grounded ice. Strictly speaking, the calving front does not refer most of these grounded-terminated margin. Please add more clarification on this issue and define terms used in this paper in Introduction. The manuscript is clear enough overall so that I don’t see a strong need to change the terms entirely in this paper, but some clarification is necessary. You do not need to provide a long argument about terminology, but please make your own judgement which terms are most appropriate and provide a short summary in the response letter.

2. It is often said “front retreat”, but more accurately I think the authors generally refer “front position movement”, including both retreat and advance (e.g. P1L12).

3. Most of geographical names mentioned in the paper are shown in Figs. 1 and 2, but not all. I commented below as I see this issue; please carefully review the manuscript and make sure that the all names are labeled in these figures. It is also helpful if relatively not-well-known names are assocaited with the name of regions, such as “xx glacier in Dronning Mauld Land” using the regional name shown in Fig. 1. At an appropriate location (end of Introduction, or first time when a geographical name is mentioned in the paper), please mention that all geographical names are shown in Figs. 1 or 2.

4. Snowmelt is shown with the unit of mm w eq. per day. Why is this unit chosen? Snowmelt is examined over three months, December, January, and February, in 90 days in total (P7top). Is it better to show snowmelt in the unit of “mm water equivalent per year” (i.e. current value times 90)?

5. Section 4.8 present correlations between climate variables and calving front position movement. Are both 1997-2008 and 2009-2018 period data used together? And then why are the reference periods shown separately? This point should be better clarified in the text.

Minor issues.

P1L23: remove CDW (you don’t need to define it in Abstract).

P2L55-56: maybe better to explicitly mention ice rumples (pinning points), though it is included in bed topography in general.

P3L91: add “in Antarctic Peninsula” after Wordie Ice Shelf. Wordie is shown in Fig. 2 but still some geographical guide is very useful for readers.

P6L121: do not cite the dataset as NSIDC 1997 or such (there are several more cases when datasets are cited).

P6L126: change the title to “ERA 5 reanalysis data”

P7L148: change to “lateral resolution”?

P8L182: methods (plural)

P9L224: confusing. Better to say “for the three time periods 1982 – 1996, 1997 – 2008, and 2009-2018. The first period is used as the reference period to measure temporal changes in the following two decades.”

P11L255: change to West Antarctica. (I like your style not to use AP, EAIS, and WAIS in the main text, which is much easier to read than the other style so please keep it more consistent).

P11L259: confusing sentence. Maybe “Excluding these two ice shelves, the rest of West Antarctica …”

P11L261 and elsewhere: I am not an English native speaker but “within the first decade” sounds like you have data to show variability within the decade.

P13L291: cite Fig. 4 beginning of Section 4.3, not very end.

P14: change EAIS and WAIS to East Antarctica and West Antarctica at all locations in this section.

P14L310: Add Celsius at several locations(here -0.5oC and at the bottom of the page +0.25oC). Also change kelvin to oC here and at other places.

P15L32: cite Fig. 6 at the beginning of this section.

P15L334: cite Fig. 7 at the beginning of this section.

P17L354: Figure 8 (not 9).

P18LL365, 366, and 368ff: This is a good example. It is said “retreat” but is it better to say “position”?

P18L375ff: do not define r_summer or such, and write it like “(r = 0.18 for summer and r=0.23 for winter)”

P20L408: is it “exceptionally” positive? Better to be a bit more specific. The other two larger peaks are mentioned at another part of the paper, and now smaller peaks are referred as exceptionally positive.

P20L415: change to 1998/1999.

P20L417 and 419: Wordie Bay and Marguerite Bay are referred. Is it possible to call these bays using ice shelf names in Fig. 3? If you decide to refer these bays, add them to Fig. 2.

P20L427: typo? Surface melt instead of basal melt

P21L445: change to “increase surface melt”

P21L450-451: better to say “it remains unclear whether….”

P21L463: what is Larsen D-G?

P22L472: change to West Antarctica (Section 5.2 header)

P22L476: here and at many other places it is said “an entire area of xx”. Do you need to say “entire area” at these locations? Is it clear enough if you say “an area of xx”?

P22L476: did you estimate the iceberg areas using BYU dataset? Then clarify the data source.

P22L479 and 480: change to A38 and A39, and A43 and A44.

P22L487: Did you measure it over the calving area or over the ice shelf including the calving area? Confusing.

P22L487 and 488: Here it is said Ronne-Filchner Ice Shelf, but it is refereed as Ronne Ice Shelf at other locations. Please keep it consistent.

P22L496: change “reference mean” to “reference period”.

P23L522 Nickerson Ice shelf does not appear in Fig. 3

P23L526 change to East Antarctica

P23 bottom: cite Fig. 2

P24L543: typo? “in sea ice no wind direction”?

P24L544 and 545: change to “up to -1oC” and “up to -0.49oC” to keep this paper consistent.

P24L554: typo, CDW.

P24L561: can you be more specific than “more recent calving event”?

P25L568: change 1982-1996 to the reference period.

P25L578: change northern and southern to seaward and landward.

P25L584: who is the authors? Revise this sentence for clarity.

P25L595ff: calving area along the Dronning Maud Land was analyzed in this paper, Goel et al. : Characteristics of ice rises and ice rumples in Dronning Maud Land and Enderby Land, Antarctica, J. Glaciol., doi: 10.1017/jog.2020.77, 2020. 1-15, 2020.

P25bottom: change +0.9 – 1.8oC

P26L619: change “measured changes” to “measured increases”?

P27L654 and 660: do you use “break-up events” to refer only tabular iceberg calving? If they are used to distinguish infrequent large calving events other more frequent calving events, it is fine. However, if otherwise, please revise them to calving events.

P28L684: add data source after “natural calving cycle”

P29L707: typo, CDW

Figure 1: Add reference to LIMA mosaic. I suggest that Figure 1 shows regional names and non-ice-shelf names such as bays, whereas Fig. 2 shows all ice-shelf names. For example, it is unclear whether the label “Wordie” refers Wordie Bay or Wordie Ice Shelf (Fig. 3 also shows Wordie). Also “Shirase” appears both in Figs. 1 and 2, but it is said “Shirase Bay” in Fig. 1 and Shirase in Fig. 2 so it is clearer. Also, please consider whether bays are needed to refer in this paper.

Figure 2: Add the boundary of EP-F and E-EP over the Ross Ice Shelf. Similarly add the boundary over the Ronne-Filchner Ice Shelf. This is an important boundary to distinguish EAIS and WAIS. To show the boundaries in the Peninsula more clearly, is it possible to add a zoom-up panel showing Peninsula?

Figure 3: re-consider the colorbar used for the absolute plot. This colorbar is suitable to show positive/negative anomalies but not good to show absolute values. In the caption add “(1982-1996)” after “the reference mean” to improve clarify (you don’t need to do it every time but it is the first time to show the reference mean/period).

Figs. 4, 5, and 7 do not show the reference period (probably for space saving purpose). However, I think another panel showing the reference period is very useful, particularly for Fig. 7 because general wind direction is useful when “weaken easterlies” or “strengthen westerlies” are said. If space is still your concern, consider adding the reference panel as the supplement.

Fig. 6: change the top right panel title to “Reference” (now it is said “long-term”). If you keep this unit, clarify in the caption that snowmelt is measured over 90 days from December to February.

Fig. 7: do not define acronym in the caption. Remove CDW from here and define CDW in the main text.

Figure 8: use background color to show the reference and following two decades. The dash bars do not work well for this purpose. Also, update the reference for SAM; the data are shown to 2018 here, but the data source was published in 2003. Is this correct?

Table 2: the second table top left cell shows “total”. Typo? Maybe “basin” or just keep it empty.

I look forward seeing the revised manuscript.

Kenny Matsuoka
TC/TCD Editor

Thanks for submitting a revised manuscript. Your revisions are mostly satisfactory, and I am happy to accept the manuscript with technical corrections listed below. Please carefully check citations for all datasets (see below). If the guidance below is not clear enough, please contact me. Otherwise, the revised manuscript will be sent to the publication process.

Congratulations.

Kenny Matsuoka
TC/TCD Editor

# Requested corrections (page/line numbers are for the track-change manuscirpt)

P4L105: “Labels of coastal sectors are shown in…..”

P5L118 and P5L121: Follow citation guidance at these URL. For example, the first one should be cited as

Jezek, K. C., J. C. Curlander, F. Carsey, C. Wales, and R. G. Barry. 2013. RAMP AMM-1 SAR Image Mosaic of Antarctica, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/8AF4ZRPULS4H. [Date Accessed].

P6L153, P6L159, P7L172, P8L201, P22L490 (and elsewhere): include data URL or appropriate citation at each location. Although they are listed again in “Data availability section”, citing data here is more convenient for readers. Like the above two, please cite data correctly.

P17L366: change to “2014/2015” (typo)

P17L370, caption of Fig. 8: change to Marshall et al.

P22L490: BYU, not BUY

P26L623: Remove "only" (these two ice shelves are mentioned as examples of possible unpinning, but it does not infer that they are the only two in Goel et al.).

P28L680-685: Check sentences.

P30L57ff: show the data generated by this study and others separately. Also, citation to Radarsat 1997 and MODIS 2009 should be updated. Typo, BUY.

Supplement
Figure S3 caption: clarify wind directions correspond to westerlies/easterlies.

Supplement 2: more explanations are necessary for this table.
1. Clarify the coordinate system for X and Y (and in the table these are shown as small letters x and y)

2. The sentence “Distance changes were only estimated based on front width!” is confusing and need to be revised. I think that Advanced and retreated distances are calculated as the observed advanced/retreated areas divided by the widths.