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Channelized melt beneath Antarctic ice shelves previously underestimated

Nature Climate Change (2026)Cite this article

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Abstract

While of critical importance for coastal communities, Antarctica’s future sea-level contribution remains highly uncertain. This uncertainty largely stems from the complex interaction between the ocean and the ice shelves, which is both difficult to observe and model. To better understand and constrain land-ice response to reduced buttressing exerted by ice shelves, efforts are needed to fully comprehend basal melt rates and their impact on ice shelf weakening and retreat. Here we present high-resolution basal melt maps (50 m) of vulnerable ice shelves based on a combination of stereo imagery and satellite altimetry, revealing pronounced channelized melting patterns whose melt rates were previously substantially underestimated (42–50%), which could result in faster channel breakthrough. Accurately simulating small-scale dynamics in ice-sheet models remains challenging but is essential for accurate sea-level rise projections.

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Data availability

The derived channel product and BURGEE basal melt rates are publicly available (https://doi.org/10.4121/4e2ba9a9-7b1b-4837-b52d-036f8c876e67)46. REMA strips and mosaics are available from the Polar Geosptaital Center (https://www.pgc.umn.edu/data/rema/), CryoSat-2 data are available from the European Space Agency (https://earth.esa.int/eogateway/documents/20142/37627/CryoSat-Baseline-D-Product-Handbook.pdf) and MEaSUREs ITS_LIVE velocities and BedMachine v.3 are both available from NASA National Snow and Ice Data Center (https://doi.org/10.5067/6II6VW8LLWJ7 and https://nsidc.org/data/NSIDC-0756/versions/3). The ref. 8 basal melt product is available via Zenodo at https://doi.org/10.5281/zenodo.8052519 (ref. 47) and the melt product from ref. 7 is available from UC San Diego (https://doi.org/10.6075/J04Q7SHT). The ice shelf damage product is available from the 4TU research data repository (https://doi.org/10.4121/911e8799-f0dc-42e3-82b4-766ad680a71e.v2). The polynyas and manually derived channels from ref. 12, the basal melt rates of Pine Island from ref. 9 and the model results of the impact of secondary flow on channel breakthrough from ref. 17 are available from the respective authors on request.

Code availability

The BURGEE code (v.1 and v.2) is publicly available (https://github.com/aszinck/BURGEE)48 and code for the channel analysis and deriving channels is available via Zenodo at https://doi.org/10.5281/zenodo.17671626 (ref. 49).

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Acknowledgements

This study is a part of the HiRISE project funded by the Dutch Research Council (NWO, no. OCENW.GROOT.2019.091).

Author information

Author notes

  1. Ann-Sofie P. Zinck

    Present address: Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark

Authors and Affiliations

  1. Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, the Netherlands

    Ann-Sofie P. Zinck, Stef Lhermitte & Bert Wouters

  2. Department of Earth & Environmental Sciences, KU Leuven, Leuven, Belgium

    Stef Lhermitte

  3. ESRIN, European Space Agency, Rome, Italy

    Martin G. Wearing

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Contributions

The research was designed by A.-S.P.Z., S.L. and B.W. and carried out by A.-S.P.Z. M.G.W. made substantial contributions to the interpretations of the results. The writing of the paper was led by A.-S.P.Z. with input from all authors.

Corresponding author

Correspondence to Ann-Sofie P. Zinck.

Ethics declarations

Competing interests

M.G.W. is employed by European Space Agency (ESA) who are responsible for satellite radar altimeter CryoSat-2. ESA had no involvement in the study and did not provide funding. The rest of the authors declare no competing interests.

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Nature Climate Change thanks Winnie Chu, Tyler Pelle and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Basal melt rate comparison.

Basal melt rates from this study are marked with 1 and melt rates from Adusumilli7 are marked with 2. Panels a–i show the individual ice shelves as marked in the bottom legend. The Ninnis ice shelf (g) is not covered by Adusumilli7. The black line denotes the BedMachine V3 grounding line43. The circles denote total ice-shelf wide basal melt rate in Gt/yr, only considering areas covered by both BURGEE, Adusumilli7, and Davison8. Note that, for example, different acquisition times (Suppl. Fig. 9) and radar penetration depth, can cause visible seams in the BURGEE melt maps (Supplementary Information S1). All panels use MODIS50 as background imagery and are generated using Quantarctica51. The Quantarctica package is published under a Creative Commons Attribution 4.0 International License.

Extended Data Fig. 2 Basal melt rate distributions.

Basal melt rate probability density functions of Adusumilli7, Davison8, and BURGEE melt rates, the latter at the original 50 m posting and interpolated (nearest-neighbour) onto the 500 m grid used in Adusumilli7. Distributions are grouped by different ice shelf thickness sections based on BedMachine V343 and only areas covered by all melting products are considered (thus excluding Ninnis Ice Shelf). In the lower subpanels, the thick, vertical black line represents the median melt rate, the solid box ranges from the first to the third quartile, and the whiskers extend the box to 1.5x the inter-quartile range. The total area considered is 19,539 km2, which in pixels correspond to 19,539 for Davison8, 84,382 for Adusumilli7 and BURGEE 500 m, and 7,801,438 for BURGEE 50 m.

Extended Data Fig. 3 Ice thickness and basal channels.

a–i, BedMachineV3 ice thicknesses43 overlaid with detected channels (’all channels’) of Pine Island (a), Thwaites (b), Dotson/Crosson (c), Drygalski (d), Cook (e), Mertz (f), Ninnis (g), Moscow University (h) and Totten (i) ice shelves. All detected channels are further sub-categorized into slope-corrected channels which represent channels with maximum slopes < 15°. Only a subset of the slope-corrected channels is studied (‘studied channels`), namely those channels where the 90% percentile melt rate is > 10 m/yr, as they are considered to be ”active” melt-channels. Persistent polynya locations from ref. 24 are marked by red diamonds. Lettering corresponds to Extended Data Fig. 1. The solid black line denotes the BedMachine V3 grounding line43. All panels use MODIS50 as background imagery and are generated using Quantarctica51. The Quantarctica package is published under a Creative Commons Attribution 4.0 International License.

Extended Data Fig. 4 Channel peak melt rates and normalized breakthrough times (NBTs).

a) Channel peak melt rates compared to ice shelf thicknesses outside the channels. Dashed lines connect peak melt rates from the different products of the same channel. Filled markers indicate channels with a characteristic channel width of 1.5-3.5 km, which is comparable to the characteristic channel width (2.5 km) used to obtain NBTs17. Unfilled markers represent all other channels (only narrower). Dashed square marks the zoomed-in region in b). In the lower subpanel, the thick, vertical black line represents the median peak melt rate, the solid box ranges from the first to the third quartile, and the whiskers extend the box to 1.5x the inter-quartile range. The box plots are based on 88, 107, and 108 (sub-)channels for Adusumilli7, Davison8, and BURGEE, respectively. b) Zoom-in of channel peak melt rates compared to ice shelf thicknesses outside the channels and NBTs obtained from ref. 17. An NBT of 1 is when linear breakthrough and breakthrough with secondary flow are equal. Linear breakthrough times are shown in Suppl. Fig. 7.

Supplementary information

Supplementary Information

Supplementary Figs. 1–16, Supplementary Table 1 and Supplementary Discussions 1 and 2.

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Zinck, AS.P., Lhermitte, S., Wearing, M.G. et al. Channelized melt beneath Antarctic ice shelves previously underestimated. Nat. Clim. Chang. (2026). https://doi.org/10.1038/s41558-025-02537-1

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