the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Mar 2026
The new kids on the block of Arctic coasts – Formation and Morphodynamics of Paraglacial Moraine Lagoons in Svalbard
Abstract. As Arctic amplification accelerates glacier retreat, new dynamic landscapes are emerging at the interface of terrestrial and marine systems. This study identifies and analyses a distinct coastal landform: the Paraglacial Moraine Lagoon (PML). Formed by coastal barriers composed of terminal or lateral moraines deposited during the Little Ice Age, PMLs represent a critical yet understudied component of the glacier–climate change feedback system. Using a multi-decadal record (1936–2024) comprising aerial photography, satellite imagery, and the Digital Shoreline Analysis System (DSAS), we quantified the evolution of fourteen PML systems across the Svalbard Archipelago. Our results show that PMLs now occupy over 56 % of Svalbard's total lagoon area (ca. 83 km2), nearly triple the area they occupied in the 1930s. We identify two divergent evolutionary trajectories: (1) an erosional–fragmenting pathway (e.g., Tjuvfjordlaguna), where marine forcing leads to barrier narrowing and inlet expansion, and (2) a stabilizing–isolating pathway (e.g., Femtelaguna), where land-terminating glaciers drive rapid terrestrial sediment infilling and barrier progradation. We argue that PMLs function as essential "paraglacial sinks" trapping glaciogenic sediments and organic matter, thereby creating sheltered biodiversity hubs in otherwise harsh coastal environments. As transient features, the formation and eventual destruction of PMLs serve as a high-resolution proxy for the rapid paraglacial adjustment of polar coastlines.
- Preprint
(2356 KB) - Metadata XML
-
Supplement
(1304 KB) - BibTeX
- EndNote
Status: open (until 29 Apr 2026)
- RC1: 'Comment on egusphere-2026-1226', Anonymous Referee #1, 21 Apr 2026 reply
-
RC2: 'Comment on egusphere-2026-1226', Sergej Olenin, 21 Apr 2026
reply
General Evaluation
This manuscript presents a timely and well-executed study of emerging coastal landforms in Svalbard, defined as Paraglacial Moraine Lagoons (PMLs). The use of a multi-decadal dataset (1936–2024) combined with geomorphological and the Digital Shoreline Analysis System (DSAS)-based shoreline analysis provides a strong empirical foundation. The identification of two contrasting evolutionary pathways (erosional vs stabilizing) and the proposed conceptual model are particularly valuable contributions.
Overall, the manuscript is scientifically sound, novel, and relevant, and it has clear potential for publication. However, several aspects require clarification and refinement, particularly regarding the definition and novelty of PMLs, the strength of some interpretations, and the depth of the Discussion.
Recommendation: minor revision
Specific Comments
- Conceptual clarity
The introduction of PMLs is a key contribution, but the definition remains somewhat broad. The manuscript would benefit from:
- a clearer diagnostic definition (criteria for classification),
- a stronger distinction from other lagoon types (e.g. deltaic or moraine-dammed systems),
- a more cautious framing of PMLs as a “formalized” rather than entirely “new” landform type.
- Interpretation of ecological and sedimentary roles
Statements regarding PMLs as biodiversity hubs and sediment/carbon sinks are interesting but appear somewhat speculative based on the data presented. These claims should be either softened or more clearly framed as hypotheses for future research, and, where possible, supported by relevant recent studies on Svalbard lagoons.
- Results
The Results section is strong and represents one of the main strengths of the paper. The quantified expansion of lagoon area and the clear documentation of morphodynamic variability are particularly convincing. Some descriptive parts could be slightly shortened.
- Discussion
The Discussion would benefit from:
- stronger synthesis (clear hierarchy of controlling processes),
- reduced repetition of Results,
- broader contextualisation (e.g. relevance to other Arctic regions),
- tighter integration of the conceptual model.
- Minor points
- Simplify long sentences for clarity.
- Avoid repetitive phrasing (e.g. “it is worth noting that”).
- Ensure consistent terminology throughout.
Conclusion
This is a strong and original contribution to Arctic coastal geomorphology. With clearer conceptual framing and slightly more cautious interpretation, the manuscript will be suitable for publication and likely to have significant impact.
Citation: https://doi.org/10.5194/egusphere-2026-1226-RC2
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 140 | 55 | 18 | 213 | 28 | 9 | 13 |
- HTML: 140
- PDF: 55
- XML: 18
- Total: 213
- Supplement: 28
- BibTeX: 9
- EndNote: 13
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
General comments
This is a well-written paper that highlights the emergence of Paraglacial Moraine Lagoons (PMLs) and their role within the glacier–fjord/sea system in Svalbard. These features were identified using a multi-method GIS approach, including DSAS, which produced retreat-rate data and a series of quantifiable maps. Although PMLs are rapidly changing features (on geomorphic timescales), they represent an interesting component of the Svalbard landscape, and their full impact on ecological and food-web systems remains understudied. The paper presents a model of PML evolution since the Little Ice Age (LIA).
I was, however, somewhat confused by the authors’ definition of what constitutes a PML. The authors state that they analyse a complete set of 14 PMLs across Svalbard, but further clarification is needed regarding how these features are defined. This may seem basic, but are the authors assuming that PMLs form only proximal to the glacier terminus? There is geomorphic evidence of small “lagoons” forming on one side of the proglacial environment but not the other. Based on the authors’ descriptions, these might also be classified as PMLs, since they are associated with moraines. This only became clearer in lines 267–270. I strongly suggest adding an explanatory definition earlier in the paper (around line 65), or moving lines 267–270 to the Introduction.
Section 5.3
I understand the authors’ argument that PMLs may act as refugia for ecological and fjord food-web systems, and this is likely correct. However, this section is currently too vague. If the authors wish to retain it, it requires further development. For example, they could discuss specific components of the food web that have been altered or established as a direct consequence of PML formation (with appropriate citations). Is there evidence of benthic species establishing themselves after PML formation? Alternatively, do the authors consider the transient nature of PMLs too rapid for species establishment? If so, which species? Without clear empirical evidence, this discussion remains speculative.
It may also be worth considering moving this section to the end of the paper and framing it as an area for future research. In its current form, it appears somewhat disconnected and disrupts the overall flow.
There should also be a comparison between the authors’ calculated glacier retreat rates and previously published retreat rates for the same glaciers (where available). How do these values compare, and what might explain any differences? This could be incorporated into Section 4.2.
Specific comments
Figures 2–7:
While I understand the authors’ intention to show detailed landscape and lagoon-size changes, these figures are somewhat repetitive. It may be more effective to combine them into a single multi-panel figure (a, b, c, etc.). This would also benefit the reader by allowing easier comparison across sites.
Figure 8:
Please include the orthophoto date from NPI (presumably 2010?).
Figure 12:
It is not immediately clear from the figure what distinguishes panels E and F. Including the explanation from line 398 in the caption would improve clarity.
Table 4:
Revise the caption to define EPR and NSM. I had to refer back in the text for clarification; including this information in the caption would improve readability.
Table 5:
Consider merging this dataset with another table (e.g., Table 1) to reduce the total number of tables. Additionally, the terms “leaky” and “choked” should be explicitly defined. While their meaning can be inferred, a clear explanation is preferable. Since “leaky” is also used in line 272, a definition is necessary.
Line-specific comments