Substantial contribution of slush to meltwater area across Antarctic ice shelves

Surface melting occurs across many of Antarctica’s ice shelves, mainly during the austral summer. The onset, duration, area and fate of surface melting varies spatially and temporally, and the resultant surface meltwater is stored as ponded water (lakes) or as slush (saturated firn or snow), with im...

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Bibliographic Details
Published in:Nature geoscience 2024-07, Vol.17 (7), p.624-630
Main Authors: Dell, Rebecca L., Willis, Ian C., Arnold, Neil S., Banwell, Alison F., de Roda Husman, Sophie
Format: Article
Language:English
Subjects:
704/106/125
704/106/694
704/106/694/2739
Air Content
Albedo
Antarctic ice
Antarctic ice shelves
Climate
Climate models
Earth and Environmental Science
Earth Sciences
Earth System Sciences
Energy balance
Firn
Geochemistry
Geology
Geophysics/Geodesy
Ice
Ice cover
Ice sheets
Ice shelves
Land ice
Landsat
Machine learning
Melting
Meltwater
Regional climate models
Regional climates
Regional variations
Remote sensing
Satellite imagery
Slush
Snowmelt
Surface energy
Surface energy balance
Surface properties
Thermal evolution
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Summary:Surface melting occurs across many of Antarctica’s ice shelves, mainly during the austral summer. The onset, duration, area and fate of surface melting varies spatially and temporally, and the resultant surface meltwater is stored as ponded water (lakes) or as slush (saturated firn or snow), with implications for ice-shelf hydrofracture, firn air content reduction, surface energy balance and thermal evolution. This study applies a machine-learning method to the entire Landsat 8 image catalogue to derive monthly records of slush and ponded water area across 57 ice shelves between 2013 and 2021. We find that slush and ponded water occupy roughly equal areas of Antarctica’s ice shelves in January, with inter-regional variations in partitioning. This suggests that studies that neglect slush may substantially underestimate the area of ice shelves covered by surface meltwater. Furthermore, we found that adjusting the surface albedo in a regional climate model to account for the lower albedo of surface meltwater resulted in 2.8 times greater snowmelt across five representative ice shelves. This extra melt is currently unaccounted for in regional climate models, which may lead to underestimates in projections of ice-sheet melting and ice-shelf stability. Analysis of satellite imagery suggests that slush accounts for approximately half of the total meltwater area across Antarctic ice shelves.
ISSN:1752-0894
1752-0908
DOI:10.1038/s41561-024-01466-6