the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 Jan 2026
Modelling the effects of proglacial lake filling and drainage on lake-terminating glacier dynamics
Abstract. The rapid retreat of glaciers worldwide is leading to the formation and expansion of proglacial and ice-marginal lakes. Proglacial lakes not only influence glacier dynamics and contribute to accelerated mass loss, but also pose a growing risk of Glacial Lake Outburst Floods (GLOFs), particularly as warming intensifies in polar and high-mountain regions. Despite important feedbacks between glacier behaviour and lake expansion, ice–lake interactions remain understudied compared to ice–ocean processes, introducing considerable uncertainty in projections of future mass loss. In this study, we use the Ice-sheet and Sea-level System Model (ISSM) in a semi-synthetic domain to explore a critical, yet often overlooked, aspect of ice–lake interaction: lake level fluctuations driven by filling and drainage events. We find that lake-terminating glaciers experience thinning and enhanced velocities compared to glaciers with a land terminus, consistent with widely observed responses to proglacial lake damming; these responses manifest even at low water levels but increase with lake depth. The lake influence extends beyond the immediate basin, as ice thickness and velocity changes propagate upstream and to neighbouring outlets. Our results also reveal that glacier responses to lake level fluctuations are highly non-linear. The onset of flotation due to rising lake levels dramatically increases grounding line mass flux and, depending on relative magnitudes of lake filling and glacier thinning, may lead to rapid retreat. Steady lake drainage instead reduces mass loss. However, we find that rapid drainage events (seasons to years) can destabilise the ice front by altering the stress regime sufficiently to enhance crevasse formation and calving. Our findings imply that while sudden drainage events may exacerbate lake-triggered glacier instability, controlled, gradual lake drainage may serve as a viable geoengineering approach to mitigate glacier mass loss and related flood hazards.
- Preprint
(1985 KB) - Metadata XML
- BibTeX
- EndNote
Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-172', William Armstrong, 06 Mar 2026
-
RC2: 'Comment on egusphere-2026-172', Anonymous Referee #2, 10 Mar 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-172/egusphere-2026-172-RC2-supplement.pdf
-
CC1: 'Comment on egusphere-2026-172', Lavkush Patel, 11 Mar 2026
This manuscript presents a rigorous and timely investigation of lake–terminating glacier dynamics, revealing critical non-linear feedback between proglacial lake levels, ice flotation, and grounding line flux with important implications for glacier stability and hazard assessment.”
Introduction
Some suggestions
- Some references to “marine ice sheet instability” are appropriate, but a clearer distinction between marine vs lake-terminating glacier analogs would help prevent overgeneralization.
- Inclusion of a brief discussion on the limitations of previous models (e.g., neglect of transient lake level changes, hydrostatic effects) would better justify the novelty of the current experiments.
Methods
Experimental design is robust and systematic, with three clear experiments: lake vs land termini, lake level fluctuations, and rapid drainage stress response. The model explicitly isolates hydrostatic effects from climatic forcing and frontal ablation, allowing clean attribution of observed glacier responses to lake interactions.
Some suggestions for improvement
- The flat lake bathymetry assumption is a simplification; discussion of how this may influence flotation thresholds and grounding line flux would improve interpretation.
- The exclusion of frontal ablation, calving, and subaqueous melt should be more prominently acknowledged, as these processes are known to be significant drivers of mass loss in lake-terminating glaciers.
- Basal hydrology is simplified; consider discussing how subglacial water pressure variability could alter basal drag and modify the response to lake level changes.
- A sensitivity analysis for key model parameters (ice viscosity, friction coefficients, lake depth) would strengthen confidence in the reported magnitudes of thinning, velocity, and GL flux changes.
- Explicit numerical or functional forms of mass flux and stress calculations could be included in supplementary materials to enhance reproducibility.
Results
Experiment 1 – Lake vs Land Terminating:
- Include quantitative uncertainty ranges for percentage changes; this will help assess significance and real-world relevance.
Experiment 2 – Lake Level Fluctuations:
- Consider integrating figures or tables summarizing the scaling relationships between rate/magnitude of lake change and GL flux or ice velocity. This would make key results more digestible.
Experiment 3 – Rapid Lake Drainage & Stress:
- Mechanistic explanation of stress amplification is strong and well-linked to calving potential.
- Quantify the spatial extent of stress perturbations relative to glacier dimensions; this would clarify the impact of drainage events on overall glacier stability.
- The link between tensile stress and potential crevasse depth is insightful; however, variability due to ice temperature and rheology should be explicitly discussed.
Discussion
The discussion successfully links modeled processes to observations in Greenland and High Mountain Asia. The study provides mechanistic insight into flotation thresholds, asymmetry of responses, hysteresis, and upstream propagation effects. The implications for glacier stability, GLOF hazard mitigation, and proactive monitoring are clearly articulated.
- Some arguments could be strengthened by explicitly comparing the magnitude of modeled responses to observed rates of thinning and velocity change in field studies.
- The potential amplification of effects if calving and subaqueous melt were included should be discussed quantitatively or via a conceptual estimate.
- Consider discussing how glacier geometry (width, slope, over-deepened basins) interacts with lake dynamics to generalize results beyond the modeled idealized catchment.
Conclusions
Concisely summarize the key findings: lake-terminating glaciers thin and accelerate, flotation thresholds are critical, rapid drainage produces stress responses, and gradual drainage stabilizes the glacier. Emphasizes relevance for hazard mitigation and glacier management, with direct applications for High Mountain Asia and Greenland Ice Sheet.
- Could highlight remaining uncertainties, including neglected processes (frontal ablation, subaqueous melt, complex basal hydrology) and how they might modify results.
- Suggest including explicit recommendations for observational campaigns to test model predictions, e.g., monitoring grounding line flux, ice velocity near proglacial lakes, and stress/crevasse formation following lake drainage.
Additional General Comments
Consider including schematic diagrams summarizing mechanisms (buoyancy, basal drag, flotation thresholds) to aid readers’ conceptual understanding.
Citation: https://doi.org/10.5194/egusphere-2026-172-CC1
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 248 | 169 | 22 | 439 | 19 | 33 |
- HTML: 248
- PDF: 169
- XML: 22
- Total: 439
- BibTeX: 19
- EndNote: 33
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
Please see the attached pdf. To explain my selection of fair in "rigout" and good in "impact" - I think this study can & will have significant impact if the apparent study design issues highlighted in my major comments (attached pdf) are resolved. As it stands, I think the impact is also fair, because there are substantial uncertainties in what are physically meaningful results vs. artifacts from model set up/experimental design. I look forward to seeing a revised version of the manuscript, and do think the study has a lot of potential once these issues are resolved.