the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Mar 2025
Brief communication: Tropical glaciers on Puncak Jaya (Irian Jaya/West Papua, Indonesia) close to extinction
Abstract. Glaciers have been retreating for many decades on a global scale due to anthropogenic climate change, including the mostly small glaciers in the Tropics. In this brief report, we document area changes of the Puncak Jaya glaciers in South-East Asia on West Papua, Indonesia, until the present. The survey was based on high resolution multispectral satellite imagery of PlanetScope and Pléiades missions from 2023 and 2024. Additionally, we digitized and georeferenced historical glacier accounts from analogue maps, resulting in a new overview map of glacier change on Puncak Jaya since 1850 (DOI requested from Pangäa). The results show a decrease of total glacier surface area by more than 99 % since 1850 and by 64 % since the last survey in 2018. Current glacier area (in 2024) amounts to 0.165 km2. The development of Puncak Jaya glaciers is thus in line with the global shrinkage of (tropical) glaciers. Assuming the current area retreat rates to continue, it is very likely that Puncak Jaya glaciers will disappear around 2030.
Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.-
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-415', Mauri Pelto, 30 Mar 2025
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AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
We would like to thank the two referees and the editor for providing such constructive and positive feedback. We appreciate it. Below we indicate point by point how we plan to revise our manuscript in accordance with the reviewer comments. We would be delighted if these revision plans would qualify our paper for further consideration.
Please note the attached supplement, which contains our responses to the comments made by both referees.
Sincerely yours,
David Ibel, Thomas Mölg, Christian Sommer
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AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
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RC2: 'Comment on egusphere-2025-415', Anonymous Referee #2, 28 May 2025
Review of, ‘Tropical glaciers on Puncak Java (Irian Jaya/west Paupa, Indonesia) close to extinction by David Ibel and co-authors.
General comments:
Using a historical map and spaceborne satellite imagery, Ibel and others report on areal changes of small tropical glaciers in Indonesia. They show substantial retreat of these glaciers over the last 150 year with about 64% shrinkage since 2018. The data provided in this short report are certainly suitable for the Cryosphere, but I feel that the authors need to address a few major issues before the manuscript is suitable for publication. Below, I summarize those major points, and I also provide minor suggestions to improve the readability of the work.
Major comments:
- Uncertainty analysis – While I can appreciate that this contribution is submitted as a ‘brief communication’, this should not prevent the authors from reporting on the uncertainties in their data and overall reports. Glacier mapping is not perfect, even when the quality of imagery is good, and the mapper is experienced. Glacier areas (and rates of change) are reported with no uncertainties. The uncertainty in the map from 1850 CE must also be high, but it sounded like only three ‘landmarks’ were used geocoding (authors mention distortion and shifts). What translation was used? Three ground control points for the map would yield an extremely high RMSE unless a thin plate spline was used (which assumes no errors, but this really would be unrealistic anyway). I would recommend that the authors consult papers that describe how to complete an uncertainty analysis for glacier mapping (e.g. Granshaw and Fountain, 2006; Fountain et al., 2023).
- Attribution of loss – Why did the authors not attempt to attribute the observed area changes to climate drivers. The end of the discussion section points out a few possible factors which could explain these changes, but the reader is left wondering what the primary driver really is. They describe, for example, temperature changes between 1972-2000 but their data is mostly after 2000. It would be relatively easy to analyze temperature at the appropriate pressure level (they cite 550 hPa) from ERA5 over the period 1950-present for the closest grid point. Even a simple descriptive analysis may allow the authors to at least partition some of their results into climatic vs. non-climatic factors.
- Short history section is too long – While the length of this section might be fine for a full-size manuscript, I found this section to be perhaps too rich in details (e.g. do we really need to know names of past explorers for the data presented in the paper?). I would prefer to see more details that pertain to supporting the objectives of the paper and/or the reliability of the results (uncertainties).
Minor points:
Line 11: not certain what authors imply by ‘accounts’
Line 13: change to ‘In 2024, glacier area was …’
Line 14: Strike ‘very’ – a vague qualifier unless you are talking about a definition (e.g. ‘very fine sand’ is defined by a size range).
Line 27: Use ‘First’, ‘Second,’ … rather than ‘Firstly’ – less wordy.
Line 73: Either refer to their position in terms of pressure level (e.g. 500-600 hPa) ,or actual elevation above sea level. Using both is confusing since they often don’t coincide.
Line 80: As described in the major comments, I would recommend that the authors at least consult reanalysis data for attribution (at least annual or warm-season temperature anomalies).
Line 88: Do we know these glaciers actual surge? Or do the authors mean ‘advance’ or ‘underwent expansion’?
Line 111: Uppercase ‘glacier’ after Maren. Formal names use ‘Glacier’. Same logic is Green Lake but Green and Blue lakes (lowercase when referring to plural).
Line 119: Strike ‘very’
Line 120: I think the convention for units is to use superscripts ‘no slash’) so m^{3} w.e. yr^{-1} throughout
Line 120 onward: The use of the term ‘mass balance’ when referring to mass (volume) change is confusing. If you don’t have surface area I suggest you use ‘mass change’.
Line 140-145: There are few details provided so it become difficult for a reader to agree with your interpretation as to the quality of the co-registration. Can you provide some more information to support this claim (RMSE, number of control points used, etc)?
Line 151: Strike ‘very’ and throughout paper.
Lines 145-160: As described in the major comments section, more information is required and some uncertainty estimates for the glacier mapping.
Lines 165: So if Permana et al., (2019) report on these glaciers, how do your extents compare to that work? This comparison would provide you with at least some assessment of the reliability of the mapping between these projects.
Line 190: Not a big deal, but deep blue typically used to demarcate water on maps. Can you simply use a given color with varied saturation levels ? Also, showing polylines is preferred rather than polygons as one can’t see examine imagery or present-day ice.
Line 208: You can’t assert that there was no period of growth especially between 1850 CE and late 1940s since you have no data. Statement needs revision.
Line 225: If you log right panel x axis, what year does area =0.0 km2? As described in major comments section, how has temperature (500 hPa pressure level) varied over this time? ERA5 goes back to the 1950s. You can download monthly data for seasonal, annual anomaly calculation.
Line 235: There is a logic gap here. The authors suggest that attribution is not possible given the lack of meteorological data yet in the introduction there is mention of glaciers like this being good indicators of global climate. The two last authors have used reanalysis in the past. Why not do a simple analysis to help attribute changes of these glaciers?
Tables and Figures:
Fig 1 (a and b) are quite pixelated for me. Can they be reproduced at a higher resolution?
Refs:
Granshaw, F. D., & Fountain, A. G. (2006). Glacier change (1958–1998) in the North Cascades National Park Complex, Washington, USA. Journal of Glaciology, 52(177), 251−256.
Fountain, A. G., Glenn, B., and Mcneil, C.: Inventory of glaciers and perennial snowfields of the conterminous USA, Earth Syst. Sci. Data, 15, 4077–4104, https://doi.org/10.5194/essd-15-4077-2023, 2023.
Citation: https://doi.org/10.5194/egusphere-2025-415-RC2 -
AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
We would like to thank the two referees and the editor for providing such constructive and positive feedback. We appreciate it. Below we indicate point by point how we plan to revise our manuscript in accordance with the reviewer comments. We would be delighted if these revision plans would qualify our paper for further consideration.
Please note the attached supplement, which contains our responses to the comments made by both referees.
Sincerely yours,
David Ibel, Thomas Mölg, Christian Sommer
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-415', Mauri Pelto, 30 Mar 2025
Ibel et al (2025) provide a useful updated chronology of glacier extent changes from 1850-2024 of Puncak Jaya glaciers. The recent rapid area loss from 2018-2024 is important to document now. I encourage the author to discuss whether the remnants of ice are glaciers or relict ice, this includes visual observations that may distinguish. For the reader it will be valuable to include a high-resolution image that is not annotated or colorized, whether as an additional figure on an additional section of a figure, In the conclusion zoom back out to report on how this change in the last decade fits that of other glaciers in this latitude band.
Specific Comments:
7: Reword to be more accurate, recognizing that in many regions including New Zealand, Norway, Western North America and the European Alps glaciers did advance during portions 1950-1990s period. Hence it has not been many decades at a global scale. “Glaciers have been retreating for the last several decades on a global scale due to anthropogenic climate change, including the mostly small glaciers in the Tropics.
9-12: Reword this is the abstract where sources/methods need not be reviewed. “The survey was based on recent 2023 and 2024 high resolution multispectral satellite imagery of PlanetScope and Pléiades missions, that were compared with digitized and georeferenced historical glacier extent, resulting in a new overview map of glacier change on Puncak Jaya since 1850.”
17: The first paragraph discusses global temperature and regional temperatures. The focus of the paper is glacier change start your introduction with paragraph 2 and move the temperature portion down.
Figure 2: Include a PlanetScope or Pléiades image, without the annotated coloring for the reader to be able to see the actual relict ice/glacier character. Given how cloudy the region is, such imagery would be a rare view for the community.
170: Please move at least a condensed version of Table S1 into the main paper, leaving out years with limited observations. All the information in Table S5 can be put into this table as well. It is important to reference in the text here the area change of individual glaciers vs just the overall glacier area loss.
199: Given the limited area and volume are any of the remaining four ice masses in Figure 2 still glaciers? Any evidence of movement from repeat imagery or crevassing? Either way please indicate that this may just be relict ice and not glaciers anymore. All ice will vanish by 2030, though the glaciers may well be gone now. The ice thickness is referenced in line 127, with your high resolution imagery, are there any indications or estimates of ice thickness?
218: For the remaining ice the orientation is indicated as being an important component is preservation. Is there any evidence of accumulation enhancement via wind drifting or avalanching.
249: The paper begins appropriately discussing tropical glacier change. It is worth adding here other glaciers lost or nearly gone in this latitude belt. The World Glacier Monitoring Service reported that Conejeras Glacier, Colombia 4.8 N ceased to exist in 2024.
Citation: https://doi.org/10.5194/egusphere-2025-415-RC1 -
AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
We would like to thank the two referees and the editor for providing such constructive and positive feedback. We appreciate it. Below we indicate point by point how we plan to revise our manuscript in accordance with the reviewer comments. We would be delighted if these revision plans would qualify our paper for further consideration.
Please note the attached supplement, which contains our responses to the comments made by both referees.
Sincerely yours,
David Ibel, Thomas Mölg, Christian Sommer
-
AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
-
RC2: 'Comment on egusphere-2025-415', Anonymous Referee #2, 28 May 2025
Review of, ‘Tropical glaciers on Puncak Java (Irian Jaya/west Paupa, Indonesia) close to extinction by David Ibel and co-authors.
General comments:
Using a historical map and spaceborne satellite imagery, Ibel and others report on areal changes of small tropical glaciers in Indonesia. They show substantial retreat of these glaciers over the last 150 year with about 64% shrinkage since 2018. The data provided in this short report are certainly suitable for the Cryosphere, but I feel that the authors need to address a few major issues before the manuscript is suitable for publication. Below, I summarize those major points, and I also provide minor suggestions to improve the readability of the work.
Major comments:
- Uncertainty analysis – While I can appreciate that this contribution is submitted as a ‘brief communication’, this should not prevent the authors from reporting on the uncertainties in their data and overall reports. Glacier mapping is not perfect, even when the quality of imagery is good, and the mapper is experienced. Glacier areas (and rates of change) are reported with no uncertainties. The uncertainty in the map from 1850 CE must also be high, but it sounded like only three ‘landmarks’ were used geocoding (authors mention distortion and shifts). What translation was used? Three ground control points for the map would yield an extremely high RMSE unless a thin plate spline was used (which assumes no errors, but this really would be unrealistic anyway). I would recommend that the authors consult papers that describe how to complete an uncertainty analysis for glacier mapping (e.g. Granshaw and Fountain, 2006; Fountain et al., 2023).
- Attribution of loss – Why did the authors not attempt to attribute the observed area changes to climate drivers. The end of the discussion section points out a few possible factors which could explain these changes, but the reader is left wondering what the primary driver really is. They describe, for example, temperature changes between 1972-2000 but their data is mostly after 2000. It would be relatively easy to analyze temperature at the appropriate pressure level (they cite 550 hPa) from ERA5 over the period 1950-present for the closest grid point. Even a simple descriptive analysis may allow the authors to at least partition some of their results into climatic vs. non-climatic factors.
- Short history section is too long – While the length of this section might be fine for a full-size manuscript, I found this section to be perhaps too rich in details (e.g. do we really need to know names of past explorers for the data presented in the paper?). I would prefer to see more details that pertain to supporting the objectives of the paper and/or the reliability of the results (uncertainties).
Minor points:
Line 11: not certain what authors imply by ‘accounts’
Line 13: change to ‘In 2024, glacier area was …’
Line 14: Strike ‘very’ – a vague qualifier unless you are talking about a definition (e.g. ‘very fine sand’ is defined by a size range).
Line 27: Use ‘First’, ‘Second,’ … rather than ‘Firstly’ – less wordy.
Line 73: Either refer to their position in terms of pressure level (e.g. 500-600 hPa) ,or actual elevation above sea level. Using both is confusing since they often don’t coincide.
Line 80: As described in the major comments, I would recommend that the authors at least consult reanalysis data for attribution (at least annual or warm-season temperature anomalies).
Line 88: Do we know these glaciers actual surge? Or do the authors mean ‘advance’ or ‘underwent expansion’?
Line 111: Uppercase ‘glacier’ after Maren. Formal names use ‘Glacier’. Same logic is Green Lake but Green and Blue lakes (lowercase when referring to plural).
Line 119: Strike ‘very’
Line 120: I think the convention for units is to use superscripts ‘no slash’) so m^{3} w.e. yr^{-1} throughout
Line 120 onward: The use of the term ‘mass balance’ when referring to mass (volume) change is confusing. If you don’t have surface area I suggest you use ‘mass change’.
Line 140-145: There are few details provided so it become difficult for a reader to agree with your interpretation as to the quality of the co-registration. Can you provide some more information to support this claim (RMSE, number of control points used, etc)?
Line 151: Strike ‘very’ and throughout paper.
Lines 145-160: As described in the major comments section, more information is required and some uncertainty estimates for the glacier mapping.
Lines 165: So if Permana et al., (2019) report on these glaciers, how do your extents compare to that work? This comparison would provide you with at least some assessment of the reliability of the mapping between these projects.
Line 190: Not a big deal, but deep blue typically used to demarcate water on maps. Can you simply use a given color with varied saturation levels ? Also, showing polylines is preferred rather than polygons as one can’t see examine imagery or present-day ice.
Line 208: You can’t assert that there was no period of growth especially between 1850 CE and late 1940s since you have no data. Statement needs revision.
Line 225: If you log right panel x axis, what year does area =0.0 km2? As described in major comments section, how has temperature (500 hPa pressure level) varied over this time? ERA5 goes back to the 1950s. You can download monthly data for seasonal, annual anomaly calculation.
Line 235: There is a logic gap here. The authors suggest that attribution is not possible given the lack of meteorological data yet in the introduction there is mention of glaciers like this being good indicators of global climate. The two last authors have used reanalysis in the past. Why not do a simple analysis to help attribute changes of these glaciers?
Tables and Figures:
Fig 1 (a and b) are quite pixelated for me. Can they be reproduced at a higher resolution?
Refs:
Granshaw, F. D., & Fountain, A. G. (2006). Glacier change (1958–1998) in the North Cascades National Park Complex, Washington, USA. Journal of Glaciology, 52(177), 251−256.
Fountain, A. G., Glenn, B., and Mcneil, C.: Inventory of glaciers and perennial snowfields of the conterminous USA, Earth Syst. Sci. Data, 15, 4077–4104, https://doi.org/10.5194/essd-15-4077-2023, 2023.
Citation: https://doi.org/10.5194/egusphere-2025-415-RC2 -
AC1: 'Reply on RC1', David Ibel, 30 Jun 2025
We would like to thank the two referees and the editor for providing such constructive and positive feedback. We appreciate it. Below we indicate point by point how we plan to revise our manuscript in accordance with the reviewer comments. We would be delighted if these revision plans would qualify our paper for further consideration.
Please note the attached supplement, which contains our responses to the comments made by both referees.
Sincerely yours,
David Ibel, Thomas Mölg, Christian Sommer
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Thomas Mölg
Christian Sommer
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1258 KB) - Metadata XML
-
Supplement
(264 KB) - BibTeX
- EndNote
- Final revised paper
Ibel et al (2025) provide a useful updated chronology of glacier extent changes from 1850-2024 of Puncak Jaya glaciers. The recent rapid area loss from 2018-2024 is important to document now. I encourage the author to discuss whether the remnants of ice are glaciers or relict ice, this includes visual observations that may distinguish. For the reader it will be valuable to include a high-resolution image that is not annotated or colorized, whether as an additional figure on an additional section of a figure, In the conclusion zoom back out to report on how this change in the last decade fits that of other glaciers in this latitude band.
Specific Comments:
7: Reword to be more accurate, recognizing that in many regions including New Zealand, Norway, Western North America and the European Alps glaciers did advance during portions 1950-1990s period. Hence it has not been many decades at a global scale. “Glaciers have been retreating for the last several decades on a global scale due to anthropogenic climate change, including the mostly small glaciers in the Tropics.
9-12: Reword this is the abstract where sources/methods need not be reviewed. “The survey was based on recent 2023 and 2024 high resolution multispectral satellite imagery of PlanetScope and Pléiades missions, that were compared with digitized and georeferenced historical glacier extent, resulting in a new overview map of glacier change on Puncak Jaya since 1850.”
17: The first paragraph discusses global temperature and regional temperatures. The focus of the paper is glacier change start your introduction with paragraph 2 and move the temperature portion down.
Figure 2: Include a PlanetScope or Pléiades image, without the annotated coloring for the reader to be able to see the actual relict ice/glacier character. Given how cloudy the region is, such imagery would be a rare view for the community.
170: Please move at least a condensed version of Table S1 into the main paper, leaving out years with limited observations. All the information in Table S5 can be put into this table as well. It is important to reference in the text here the area change of individual glaciers vs just the overall glacier area loss.
199: Given the limited area and volume are any of the remaining four ice masses in Figure 2 still glaciers? Any evidence of movement from repeat imagery or crevassing? Either way please indicate that this may just be relict ice and not glaciers anymore. All ice will vanish by 2030, though the glaciers may well be gone now. The ice thickness is referenced in line 127, with your high resolution imagery, are there any indications or estimates of ice thickness?
218: For the remaining ice the orientation is indicated as being an important component is preservation. Is there any evidence of accumulation enhancement via wind drifting or avalanching.
249: The paper begins appropriately discussing tropical glacier change. It is worth adding here other glaciers lost or nearly gone in this latitude belt. The World Glacier Monitoring Service reported that Conejeras Glacier, Colombia 4.8 N ceased to exist in 2024.