Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Development of ice-shelf estuaries promotes fractures and calving


As the global climate warms, increased surface meltwater production on ice shelves may trigger ice-shelf collapse and enhance global sea-level rise. The formation of surface rivers could help prevent ice-shelf collapse if they can efficiently evacuate meltwater. Here we present observations of the evolution of a surface river into an ice-shelf estuary atop the Petermann Ice Shelf in northwest Greenland and identify a second estuary at the nearby Ryder Ice Shelf. This surface-hydrology process can foster fracturing and enhance calving. At the Petermann estuary, sea ice was observed converging at the river mouth upstream, indicating a flow reversal. Seawater persists in the estuary after the surrounding icescape is frozen. Along the base of Petermann estuary, linear fractures were initiated at the calving front and propagated upstream along the channel. Similar fractures along estuary channels shaped past large rectilinear calving events at the Petermann and Ryder ice shelves. Increased surface melting in a warming world will enhance fluvial incision, promoting estuary development and longitudinal fracturing orthogonal to ice-shelf fronts, and increase rectilinear calving. Estuaries could develop in Antarctica within the next half-century, resulting in increased calving and accelerating both ice loss and global sea-level rise.

This is a preview of subscription content, access via your institution

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Evidence for the Petermann estuary.
Fig. 2: Development of longitudinal fracture along the Petermann and Ryder ice-shelf rivers.
Fig. 3: Rectilinear calving and estuarine weakening at the Petermann and Ryder ice shelves.
Fig. 4: Estuary formation in Antarctica.

Data availability

Except for DigitalGlobe constellation data, all datasets used in this analysis are freely available. DigitalGlobe satellite imagery was provided by the PGC under National Science Foundation grant 1644869 and is available from the PGC upon request with eligible active research awards. Imagery-derived river widths and fracture length developed in this analysis are available at, along with MAR data used. Landsat data are available at and the Landsat Image Mosaic of Antarctica is available at OIB data are provided by the National Snow and Ice Data Center at The 1978 orthophotos are provided by the National Oceanic and Atmospheric Administration National Centers for Environmental Information at Ice-shelf elevation data are available at REMA data are available through the PGC at

Code availability

This analysis does not depend on specific code. All results can be reproduced through the equations and procedures outlined in the Methods section of this manuscript.


  1. Paolo, F. S., Fricker, H. A. & Padman, L. Volume loss from Antarctic ice shelves is accelerating. Science 348, 327–331 (2015).

    Article  Google Scholar 

  2. Rignot, E., Jacobs, S., Mouginot, J. & Scheuchl, B. Ice-shelf melting around Antarctica. Science 341, 266–270 (2013).

    Article  Google Scholar 

  3. Banwell, A. F., MacAyeal, D. R. & Sergienko, O. V. Breakup of the Larsen B Ice Shelf triggered by chain reaction drainage of supraglacial lakes. Geophys. Res. Lett. 40, 5872–5876 (2013).

    Article  Google Scholar 

  4. Banwell, A. F. & MacAyeal, D. R. Ice-shelf fracture due to viscoelastic flexure stress induced by fill/drain cycles of supraglacial lakes. Antarct. Sci. 27, 587–597 (2015).

    Article  Google Scholar 

  5. MacAyeal, D. R., Sergienko, O. V. & Banwell, A. F. A model of viscoelastic ice-shelf flexure. J. Glaciol. 61, 635–645 (2015).

    Article  Google Scholar 

  6. Scambos, T. et al. Ice shelf disintegration by plate bending and hydro-fracture: satellite observations and model results of the 2008 Wilkins Ice Shelf break-ups. Earth Planet. Sci. Lett. 280, 51–60 (2009).

    Article  Google Scholar 

  7. Kingslake, J., Ely, J. C., Das, I. & Bell, R. E. Widespread movement of meltwater onto and across Antarctic ice shelves. Nature 544, 349–352 (2017).

    Article  Google Scholar 

  8. Bell, R. E. et al. Antarctic ice shelf potentially stabilized by export of meltwater in surface river. Nature 544, 344–348 (2017).

    Article  Google Scholar 

  9. Dow, C. F. et al. Basal channels drive active surface hydrology and transverse ice shelf fracture. Sci. Adv. 4, eaao7212 (2018).

    Article  Google Scholar 

  10. DeConto, R. M. & Pollard, D. Contribution of Antarctica to past and future sea-level rise. Nature 531, 591–597 (2016).

    Article  Google Scholar 

  11. Smith, L. C. et al. Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet. Proc. Natl Acad. Sci. USA 112, 1001–1006 (2015).

    Article  Google Scholar 

  12. Trusel, L. D. et al. Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios. Nat. Geosci. 8, 927–932 (2015).

    Article  Google Scholar 

  13. Dutrieux, P. et al. Basal terraces on melting ice shelves. Geophys. Res. Lett. 41, 5506–5513 (2014).

    Article  Google Scholar 

  14. Rignot, E. & Steffen, K. Channelized bottom melting and stability of floating ice shelves. Geophys. Res. Lett. 35, L02503 (2008).

    Article  Google Scholar 

  15. Hill, E. A., Carr, J. R. & Stokes, C. R. A review of recent changes in major marine-terminating outlet glaciers in northern Greenland. Front. Earth Sci. 4, 111 (2017).

    Article  Google Scholar 

  16. Macdonald, G. J., Banwell, A. F. & MacAyeal, D. R. Seasonal evolution of supraglacial lakes on a floating ice tongue, Petermann Glacier, Greenland. Ann. Glaciol. 59, 56–65 (2018).

    Article  Google Scholar 

  17. Korsgaard, N. J. et al. Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978–1987. Sci. Data 3, 160032 (2016).

    Article  Google Scholar 

  18. Münchow, A., Padman, L. & Fricker, H. A. Interannual changes of the floating ice shelf of Petermann Gletscher, north Greenland, from 2000 to 2012. J. Glaciol. 60, 489–499 (2014).

    Article  Google Scholar 

  19. Holland, P. G. et al. in Encyclopedia of Hydrology and Water Resources (ed. Herschy, W. R.) 244–248 (Springer, 1998).

  20. Johnson, H. L., Münchow, A., Falkner, K. K. & Melling, H. Ocean circulation and properties in Petermann Fjord, Greenland. J. Geophys. Res. Oceans 116, C01003 (2011).

    Article  Google Scholar 

  21. Hill, E. A., Carr, J. R., Stokes, C. R. & Gudmundsson, G. H. Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015. Cryosphere 12, 3243–3263 (2018).

    Article  Google Scholar 

  22. Pitcher, L. H. & Smith, L. C. Supraglacial streams and rivers. Annu. Rev. Earth Planet. Sci. 47, 421–452 (2019).

    Article  Google Scholar 

  23. Scambos, T. A., Hulbe, C. & Fahnestock, M. in Antarctic Peninsula Climate Variability: Historical and Paleoenvironmental Perspectives (eds Domack, E. et al.) 79–92 (American Geophysical Union, 2003).

  24. Lazzara, M. A., Jezek, K. C., Scambos, T. A., MacAyeal, D. R. & van der Veen, C. J. On the recent calving of icebergs from the Ross Ice Shelf. Polar Geogr. 23, 201–212 (1999).

    Article  Google Scholar 

  25. Doake, C. S. M., Corr, H. F. J., Rott, H., Skvarca, P. & Young, N. W. Breakup and conditions for stability of the northern Larsen Ice Shelf, Antarctica. Nature 391, 778–780 (1998).

    Article  Google Scholar 

  26. Bassis, J. N. & Ma, Y. Evolution of basal crevasses links ice shelf stability to ocean forcing. Earth Planet. Sci. Lett. 409, 203–211 (2015).

    Article  Google Scholar 

  27. Hill, E. A., Gudmundsson, G. H., Carr, J. R. & Stokes, C. R. Velocity response of Petermann Glacier, northwest Greenland, to past and future calving events. Cryosphere 12, 3907–3921 (2018).

    Article  Google Scholar 

  28. Alley, K. E., Scambos, T. A., Siegfried, M. R. & Fricker, H. A. Impacts of warm water on Antarctic ice shelf stability through basal channel formation. Nat. Geosci. 9, 290–293 (2016).

    Article  Google Scholar 

  29. Glasser, N. F. & Scambos, T. A. A structural glaciological analysis of the 2002 Larsen B ice-shelf collapse. J. Glaciol. 54, 3–16 (2008).

    Article  Google Scholar 

  30. Trusel, L. D., Frey, K. E., Das, S. B., Munneke, P. K. & van den Broeke, M. R. Satellite-based estimates of Antarctic surface meltwater fluxes. Geophys. Res. Lett. 40, 6148–6153 (2013).

    Article  Google Scholar 

  31. Scambos, T. A., Hulbe, C., Fahnestock, M. & Bohlander, J. The link between climate warming and break-up of ice shelves in the Antarctic Peninsula. J. Glaciol. 46, 516–530 (2000).

    Article  Google Scholar 

  32. Rack, W. & Rott, H. Pattern of retreat and disintegration of the Larsen B Ice Shelf, Antarctic Peninsula. Ann. Glaciol. 39, 505–510 (2004).

    Article  Google Scholar 

  33. Howat, I. M., Porter, C., Smith, B. E., Noh, M. J. & Morin, P. The reference elevation model of Antarctica. Cryosphere 13, 665–674 (2019).

    Article  Google Scholar 

  34. Shepherd, A., Wingham, D., Payne, T. & Skvarca, P. Larsen Ice Shelf has progressively thinned. Science 302, 856–859 (2003).

    Article  Google Scholar 

  35. Warm ocean explains Antarctic ice shelf collapse. University of Cambridge (30 October 2003);

  36. MacFerrin, M. et al. Rapid expansion of Greenland’s low-permeability ice slabs. Nature 573, 403–407 (2019).

    Article  Google Scholar 

  37. Liu, H., Wang, L. & Jezek, K. C. Spatiotemporal variations of snowmelt in Antarctica derived from satellite scanning multichannel microwave radiometer and Special Sensor Microwave Imager data (1978–2004). J. Geophys. Res. Earth Surf. 111, F01003 (2006).

    Google Scholar 

  38. Bjørk, A. A., Kruse, L. M. & Michaelsen, P. B. Brief communication: Getting Greenland’s glaciers right—a new data set of all official Greenlandic glacier names. Cryosphere 9, 2215–2218 (2015).

    Article  Google Scholar 

  39. Dominguez, R. IceBridge DMS L1B Geolocated and Orthorectified Images, Version 1 (NASA National Snow and Ice Data Center Distributed Active Archive Center, 2019);

  40. Arvesen, J. C. & Dotson, R. C. Photogrammetric processing of IceBridge DMS imagery into high-resolution digital surface models (DEM and visible overlay). In: AGU Fall Meeting 2014 C21D–03 (AGU, 2014).

  41. Dee, D. et al. The ERA-Interim Reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).

    Article  Google Scholar 

  42. Lefebre, F., Gallée, H., van Ypersele, J.-P. & Greuell, W. Modeling of snow and ice melt at ETH Camp (West Greenland): a study of surface albedo. J. Geophys. Res. Atmos. 108, 4231 (2003).

    Article  Google Scholar 

  43. Smith, L. C. et al. Direct measurements of meltwater runoff on the Greenland ice sheet surface. Proc. Natl Acad. Sci. USA 114, E10622–E10631 (2017).

    Article  Google Scholar 

  44. Zuo, Z. & Oerlemans, J. Modelling albedo and specific balance of the Greenland ice sheet: calculations for the Søndre Strømfjord transect. J. Glaciol. 42, 305–317 (1996).

    Article  Google Scholar 

  45. Forster, R. R. et al. Extensive liquid meltwater storage in firn within the Greenland ice sheet. Nat. Geosci. 7, 95–98 (2013).

    Article  Google Scholar 

  46. Fettweis, X. et al. Reconstructions of the 1900–2015 Greenland ice sheet surface mass balance using the regional climate MAR model. Cryosphere 11, 1015–1033 (2017).

    Article  Google Scholar 

  47. Förste, C. et al. The GeoForschungsZentrum Potsdam/Groupe de Recherche de Gèodésie Spatiale satellite-only and combined gravity field models: EIGEN-GL04S1 and EIGEN-GL04C. J. Geod. 82, 331–346 (2008).

    Article  Google Scholar 

  48. Morlighem, M. et al. BedMachine v3: complete bed topography and ocean bathymetry mapping of Greenland from multibeam echo sounding combined with mass conservation. Geophys. Res. Lett. 44, 11051–11061 (2017).

    Article  Google Scholar 

  49. Washam, P., Nicholls, K. W., Münchow, A. & Padman, L. Summer surface melt thins Petermann Gletscher Ice Shelf by enhancing channelized basal melt. J. Glaciol. 65, 662–674 (2019).

    Article  Google Scholar 

  50. Fountain, A. G. & Walder, J. S. Water flow through temperate glaciers. Rev. Geophys. 36, 299–328 (1998).

    Article  Google Scholar 

  51. Vaughan, D. G. et al. Subglacial melt channels and fracture in the floating part of Pine Island Glacier, Antarctica. J. Geophys. Res. Earth Surf. 117, F03012 (2012).

    Article  Google Scholar 

  52. Martin, C. F. et al. Airborne Topographic Mapper Calibration Procedures and Accuracy Assessment Report No. NASA/TM–2012-215891 (NASA, 2012).

  53. Irvine-Fynn, T. D. L., Hodson, A. J., Moorman, B. J., Vatne, G. & Hubbard, A. L. Polythermal glacier hydrology: a review. Rev. Geophys. 49, RG4002 (2011).

    Article  Google Scholar 

  54. Cooper, M. G. et al. Meltwater storage in low-density near-surface bare ice in the Greenland ice sheet ablation zone. Cryosphere 12, 955–970 (2018).

    Article  Google Scholar 

Download references


We thank D. MacAyeal for helpful discussions about this manuscript. We also would like to acknowledge R. Fishman for providing imagery of the estuary, as well as M. Vogt of Volcano Heli, Iceland, for piloting the expedition to Petermann, enabling documentation of the estuary and providing imagery of the estuary. We also thank R. Boghosian for proofreading. We would have preferred to refer to the study site and features with Greenlandic/Indigenous names but were unable to find them; ‘Petermann’ was used as it is consistent with the literature39. Funding was provided by National Science Foundation grant 1644869 (A.L.B), the Old York Foundation (R.E.B.), the Heising-Simons Foundation grant PG009346_HSFOUND 2019-1160 (M.T.), the National Aeronautics and Space Administration Cryospheric Sciences Program grant 80NSSC19K0942 (L.C.S. and L.H.P.) and the National Aeronautics and Space Administration Modeling, Analysis and Prediction program award 16-MAP 16-0137 (P.M.A. and M.T.).

Author information

Authors and Affiliations



A.L.B. contributed to conceptualization and investigation of the project, methodology, data analysis and visualization, and wrote the manuscript. All authors contributed to the manuscript. L.H.P. contributed to conceptualization and investigation of the project, methodology and data analysis, and provided resources. L.C.S. contributed to the conceptualization and investigation of the project. E.K. contributed to data analysis and visualization. P.M.A. and M.T. contributed data resources and to data analysis. R.E.B. contributed to conceptualization and investigation of the project.

Corresponding author

Correspondence to Alexandra L. Boghosian.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor: Thomas Richardson, in collaboration with the Nature Geoscience team. Nature Geoscience thanks Knut Christianson and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Ocean water atop the Petermann Ice Shelf after the melt season.

a Modèle Atmosphérique Regional v. 3.9 (MAR) average daily ice-surface melt averaged across the Petermann Ice Shelf from 2010 to 2017. The red dotted lines show earliest indication of seawater in the channel after the melt season as identified in high resolution WorldView-1 and WorldView-2 satellite imagery (Extended Data Table 2). b The first evidence of water atop the ice shelf was collected by WorldView-1 in 2013 (top). Note that break in the shadow cast by the ice-shelf terminus at the Petermann river channel confirms a direct connection between the ice shelf and the ocean. Multispectral WorldView-2 images collected in 2014 (middle) and 2016 (bottom) show water in the channel directly connected to the ocean and an absence of surface meltwater elsewhere on the ice shelf. Credit: b, (2013, 2014, 2016) DigitalGlobe, Inc.

Extended Data Fig. 2 Modelled melt and snowfall on Petermann Ice Shelf.

Top: MAR simulation of daily surface melt (blue) and snowfall (gray) averaged across the Petermann Ice Shelf from 2010 to 2017. Melt and snowfall are reported in millimeters water equivalent (mmwe), which is used to represent snow or ice mass in terms of its equivalent water volume. Bottom: estuary wetted widths measured at 25 m from calving front as in Extended Data Fig. 3 from 2010 to 2017. This demonstrates the lack of correlation between estuary widening and surface runoff.

Extended Data Fig. 3 Evidence for change at the mouth of the estuary.

a Location of wetted width measurements at 1 km increments along the Petermann river set against pan-chromatic WorldView-2 image (30 August 2018). Blue line denotes the maximum extent of sea ice found in the channel, (24 July 2018). Purple line denotes the maximum extent of the longitudinal fracture (25 July 2017). Red box shows the location of Extended Data Fig. 3b. b The mouth of the Petermann estuary widened from 2012 (left) to 2018 (right). Left panel: 2012 image with river widths shown as colored lines at 25 m increments from the ice-shelf front (QuickBird image July 19th). Right panel: 2018 image with river widths at 25m increments as in left panel. The estuary is approximately three times wider in 2018. c Wetted width measurements along channel from 2010 to 2018. The channel widens at the mouth of the estuary and within 2 km from the ice-shelf front. Width measurements (points) and trendlines are colored by locations marked in Extended Data Fig. 3a,b. Fracture growth and flow reversal evidence are coincident with this widening as shown in a. Credit: a,b (left): (2012, 2018) DigitalGlobe, Inc.

Extended Data Fig. 4 Additional evidence for the Ryder Ice Shelf estuary.

(a) The Ryder estuary in a WorldView-2 image collected on 25 August 2014. Red boxes mark the location of (b) and (c), and gold star marks the approximate location of the 2019 estuary (Fig. 2c). (b) Detailed image of the downstream portion of the estuary shows water in the channel directly connected to the ocean and an absence of surface meltwater elsewhere on the ice shelf. (c) Detailed image of the upstream portion of the estuary shows water in the channel directly connected to ocean water in the rift and an absence of surface meltwater elsewhere on the ice shelf. Credit: (2014) DigitalGlobe, Inc.

Extended Data Fig. 5 Detail of longitudinal fractures at the Petermann estuary.

WorldView imagery at the Petermann estuary from which fractures were digitized (Fig. 2a). Red boxes show location of detail views. Fractures are identified as dark linear features along the bottom of the channel. Images collected on 14 July 2014; 17 July 2015; 15 July 2016; and 25 July 2017. Credit: (2014, 2015, 2016, 2017) DigitalGlobe Inc.

Extended Data Table 1 Constrains used in estuary calculations
Extended Data Table 2 DigitalGlobe images used
Extended Data Table 3 Landsat images used
Extended Data Table 4 Aerial images, DEMs and field photographs used
Extended Data Table 5 Wetted width statistics

Supplementary information

Supplementary Data 1

MAR outputs of runoff, snowfall and melt in millimeters water equivalent (mmwe). Also available for download in .mat and NetCDF at:

Supplementary Data 2

Digitized river widths and fractures. All original shapefiles are available at:

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Boghosian, A.L., Pitcher, L.H., Smith, L.C. et al. Development of ice-shelf estuaries promotes fractures and calving. Nat. Geosci. 14, 899–905 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing