The Pope, Smith and Kohler glaciers, in the Amundsen Sea Embayment of West Antarctica, have experienced enhanced ocean-induced ice-shelf melt, glacier acceleration, ice thinning and grounding-line retreat in the past 30 years. Here we present observations of the grounding-line retreat of these glaciers since 2014 using a constellation of interferometric radar satellites combined with precision surface elevation data. We find that the grounding lines develop spatially variable, kilometre-scale, tidally induced migration zones. After correction for tidal effects, we detect a sustained pattern of retreat coincident with high melt rates of ungrounded ice, marked by episodes of more rapid retreat. In 2017, Pope Glacier retreated 3.5 km in 3.6 months, or 11.7 km yr–1. In 2016–2018, Smith West retreated at 2 km yr–1 and Kohler at 1.3 km yr–1. While the retreat slowed in 2018–2020, these retreat rates are faster than anticipated by numerical models on yearly timescales. We hypothesize that the rapid retreat is caused by unrepresented, vigorous ice–ocean interactions acting within newly formed cavities at the ice–ocean boundary.
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Nature Geoscience Open Access 05 September 2022
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All data needed to evaluate the conclusions in the paper are present in the paper and/or Supplementary Information. The CSK data (original COSMO-SkyMed product ASI, Agenzia Spaziale Italiana (2007–2020)) were provided by the Italian Space Agency (ASI) and the TDX data (original TanDEM-X product DLR (2007–2019)) by the German Space Agency (DLR). CSK data are publicly available through data grants from ASI. TanDEM-X CoSSC products were through scientific proposal OTHER0103 and are publicly available. Velocity (https://nsidc.org/data/NSIDC-0484/versions/2) and BedMachine (https://nsidc.org/data/NSIDC-0756/versions/2) data products are available as MEaSUREs products at the National Snow and Ice Data Center, Boulder CO (NSIDC). Geocoded interferograms, grounding-line positions, reference surface elevation, reference ice thickness, reference height above flotation and reference ice velocity are available at https://doi.org/10.7280/D1B114.
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This work was conducted at the UC Irvine under a contract with the Cryosphere Program of NASA (17-CRYO17–0025, 80NSSC18M0083 and NNX17AI02G). E.R. acknowledges support from the NSF (F0691-04).
The authors declare no competing interests.
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Milillo, P., Rignot, E., Rizzoli, P. et al. Rapid glacier retreat rates observed in West Antarctica. Nat. Geosci. 15, 48–53 (2022). https://doi.org/10.1038/s41561-021-00877-z