Ice sheets
Proglacial lakes speed Greenland outlet glaciers
Open access · cc by · source: Europe PMC
Lake-terminating Greenland outlet glaciers flow much faster near their fronts than otherwise similar land-terminating glaciers.
Study at a glance
- Design
- Other — Paired comparison of lake- vs land-terminating Greenland outlet glaciers with ITS_LIVE velocities
- N
- N=102 · 102 lake-terminating outlets paired with land-terminating counterparts
- Population
- Greenland outlet glaciers terminating in ice-marginal lakes vs on land
- Outcome
- Near-terminus ice-surface velocity enhancement associated with proglacial lakes
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
In 2017, terminus velocity of lake-terminating glaciers was 231% higher than land-terminating glaciers. Median speeds were 43 versus 36 m yr−1 overall, and 43 versus 13 m yr−1 at 500 m inland. About 44% of lake-terminating glaciers accelerate toward the terminus, versus 3.9% of land-terminating glaciers. Effects are significant from about 3.5 km inland to the margin.
Methodology
The authors paired 102 lake-terminating outlet glaciers with land-terminating glaciers, sampled ITS_LIVE ice-surface velocities along flowlines from 500 m to 9.5 km inland, and compared 2015–2019 (plus 2000) speeds with ice-marginal lake area.
Limitations
The study does not measure calving rates or submarine melt directly, so the mechanical cause of faster flow is inferred. Lake-area–velocity relationships are noisy, and some sectors have small samples. Elevation, slope, and aspect were similar between groups except steeper land-terminating fronts.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
ITS_LIVE Landsat feature-tracking (120 m annual mosaics) on 102 Greenland lake-terminating outlet glaciers versus land-terminating pairs shows 2017 terminus velocity 231% higher at lake termini. Median speeds were 43 versus 36 m yr⁻¹ overall, and 43 versus 13 m yr⁻¹ at 500 m inland. About 44% of lake-terminating glaciers accelerate toward the terminus, versus 3.9% of land-terminating glaciers; the contrast is significant from about 3.5 km inland to the margin.
Evidence for the claim as stated.
Optical and radar ice products do not count the same objects at the same timescale. Planet UNet finds ~50% more iceberg area and ~5× more small bergs than Sentinel-2 thresholding; 12-day Sentinel-1 glacier speeds smear events that GNSS resolves daily; ITS_LIVE annual mosaics average many Landsat pairs. A student who adds Sermilik meltwater, Greenland lake-terminus speed, and Iceland spring speed-up as one ‘SAR velocity’ is mixing sensors, resolutions and averaging windows.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Optical and radar ice products do not count the same objects at the same timescale. Planet UNet finds ~50% more iceberg area and ~5× more small bergs than Sentinel-2 thresholding; 12-day Sentinel-1 glacier speeds smear events that GNSS resolves daily; ITS_LIVE annual mosaics average many Landsat pairs. A student who adds Sermilik meltwater, Greenland lake-terminus speed, and Iceland spring speed-up as one ‘SAR velocity’ is mixing sensors, resolutions and averaging windows.
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