As ice sheets load Earth's surface, they produce ice-marginal depressions which, when filled with meltwater, become proglacial lakes. We include self-consistently evolving proglacial lakes in a glacial isostatic adjustment (GIA) model and apply it to the Laurentide ice sheet over the last glacial cycle. We find that the locations of modeled lakes and the timing of their disappearance is consistent with the geological record. Lake loads can deflect topography by >10 m, and volumes collectively approach 30–45 cm global mean sea-level equivalent. GIA increases deglaciation-phase lake volume up to five-fold and average along-ice-margin depth ≤90 m compared to glaciation-phase ice volume analogs—differences driven by changes in the position and size of the peripheral bulge. Since ice-marginal lake depth affects grounding-line outflow, GIA-modulated proglacial lake depths could affect ice-sheet mass loss. Indeed, we find that Laurentide ice-margin retreat rate sometimes correlates with proglacial lake presence, indicating that proglacial lakes aid glacial collapse.
Bibliographical noteFunding Information:
This material is based upon work supported by NSF Grant EAR‐1903518 and EAR‐1903606 (JA, ADW, and KLC). ADW received further support through a research fellowship from the Alexander von Humboldt Foundation. TP received support from NSF EAR‐2120574. JA acknowledges support from the Vetlesen Foundation. We acknowledge computing resources from Columbia University's Shared Research Computing Facility project, which is supported by NIH Research Facility Improvement Grant 1G20RR030893‐01, and associated funds from the New York State Empire State Development, Division of Science Technology and Innovation (NYSTAR) Contract C090171, both awarded 15 April 2010. We thank Jerry X. Mitrovica for initial discussions and Joshua Cuzzone, Lambert Caron, and an anoymous reviewer for their useful feedback.
© 2022 The Authors.
- Laurentide ice sheet
- glacial isostatic adjustment
- proglacial lakes