Marine ice-cliff instability (MICI) processes could accelerate future retreat of the Antarctic Ice Sheet if ice shelves that buttress grounding lines more than 800 metres below sea level are lost1,2. The present-day grounding zones of the Pine Island and Thwaites glaciers in West Antarctica need to retreat only short distances before they reach extensive retrograde slopes3,4. When grounding zones of glaciers retreat onto such slopes, theoretical considerations and modelling results indicate that the retreat becomes unstable (marine ice-sheet instability) and thus accelerates5. It is thought1,2 that MICI is triggered when this retreat produces ice cliffs above the water line with heights approaching about 90 metres. However, observational evidence confirming the action of MICI has not previously been reported. Here we present observational evidence that rapid deglacial ice-sheet retreat into Pine Island Bay proceeded in a similar manner to that simulated in a recent modelling study1, driven by MICI. Iceberg-keel plough marks on the sea-floor provide geological evidence of past and present iceberg morphology, keel depth6 and drift direction7. From the planform shape and cross-sectional morphologies of iceberg-keel plough marks, we find that iceberg calving during the most recent deglaciation was not characterized by small numbers of large, tabular icebergs as is observed today8,9, which would produce wide, flat-based plough marks10 or toothcomb-like multi-keeled plough marks11,12. Instead, it was characterized by large numbers of smaller icebergs with V-shaped keels. Geological evidence of the form and water-depth distribution of the plough marks indicates calving-margin thicknesses equivalent to the threshold that is predicted to trigger ice-cliff structural collapse as a result of MICI13. We infer rapid and sustained ice-sheet retreat driven by MICI, commencing around 12,300 years ago and terminating before about 11,200 years ago, which produced large numbers of icebergs smaller than the typical tabular icebergs produced today. Our findings demonstrate the effective operation of MICI in the past, and highlight its potential contribution to accelerated future retreat of the Antarctic Ice Sheet.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Communications Earth & Environment Open Access 03 October 2022
Marine ice-cliff instability modeling shows mixed-mode ice-cliff failure and yields calving rate parameterization
Nature Communications Open Access 11 May 2021
Nature Communications Open Access 10 December 2019
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Prices vary by article type
Prices may be subject to local taxes which are calculated during checkout
Pollard, D., DeConto, R. M. & Alley, R. B. Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure. Earth Planet. Sci. Lett. 412, 112–121 (2015)
DeConto, R. M. & Pollard, D. Contribution of Antarctica to past and future sea-level rise. Nature 531, 591–597 (2016)
Joughin, I., Smith, B. E. & Medley, B. Marine ice sheet collapse potentially underway for the Thwaites Glacier Basin, West Antarctica. Science 344, 735–738 (2014)
Rignot, E., Mouginot, J., Morlighem, M., Seroussi, H. & Scheuchl, B. Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011. Geophys. Res. Lett. 41, 3502–3509 (2014)
Gudmundsson, G. H., Krug, J., Durand, G., Favier, L. & Gagliardini, O. The stability of grounding lines on retrograde slopes. Cryosphere 6, 1497–1505 (2012)
Goff, J. A. & Austin, J. A. Seismic and bathymetric evidence for four different episodes of iceberg scouring on the New Jersey outer shelf: possible correlation to Heinrich events. Mar. Geol. 266, 244–254 (2009)
Todd, B. J., Lewis, C. F. M. & Ryall, P. J. C. Comparison of trends of iceberg scour marks with iceberg trajectories and evidence of paleocurrent trends on Saglek Bank, northern Labrador Shelf. Can. J. Earth Sci. 25, 1374–1383 (1988)
Rignot, E. Ice-shelf changes in Pine Island Bay, Antarctica, 1947–2000. J. Glaciol. 48, 247–256 (2002)
MacGregor, J. A., Catania, G. A., Markowski, M. S. & Andrews, A. G. Widespread rifting and retreat of ice-shelf margins in the eastern Amundsen Sea Embayment between 1972 and 2011. J. Glaciol. 58, 458–466 (2012)
Noormets, R., Kirchner, N., Flink, A. E. & Dowdeswell, J. A. Possible iceberg-produced submarine terraces in Hambergbukta, Spitsbergen. Geol. Soc. Lond. Mem. 46, 101–102 (2016)
Batchelor, C. L., Dowdeswell, J. A., Dowdeswell, E. K. & Todd, B. J. A subglacial landform assemblage on the outer-shelf of M’Clure Strait, Canadian Arctic, ploughed by deglacial iceberg keels. Geol. Soc. Lond. Mem. 46, 337–340 (2016)
López-Martínez, J., Muñoz, A., Dowdeswell, J. A., Linés, C. & Acosta, J. Relict sea-floor ploughmarks record deep-keeled Antarctic icebergs to 45°S on the Argentine margin. Mar. Geol. 288, 43–48 (2011)
Bassis, J. N. & Walker, C. C. Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice. Proc. R. Soc. Lond. A 468, 913–931 (2012)
Paolo, F. S., Fricker, H. A. & Padman, L. Volume loss from Antarctic ice shelves is accelerating. Science 348, 327–331 (2015)
Smith, J. A. et al. Sub-ice-shelf sediments record history of twentieth-century retreat of Pine Island Glacier. Nature 541, 77–80 (2017)
Hillenbrand, C.-D. et al. West Antarctic Ice Sheet retreat driven by Holocene warm water incursions. Nature 547, 43–48 (2017)
Rignot, E. Changes in West Antarctic ice stream dynamics observed with ALOS PALSAR data. Geophys. Res. Lett. 35, L12505 (2008)
Favier, L. et al. Retreat of Pine Island Glacier controlled by marine ice-sheet instability. Nat. Clim. Chang. 4, 117–121 (2014)
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)
Pfeffer, W. T., Harper, J. T. & O’Neel, S. Kinematic constraints on glacier contributions to 21st-century sea-level rise. Science 321, 1340–1343 (2008)
Levermann, A. et al. Projecting Antarctic ice discharge using response functions from SeaRISE ice-sheet models. Earth Syst. Dynam. 5, 271–293 (2014)
Larter, R. D. et al. Reconstruction of changes in the Amundsen Sea and Bellingshausen Sea sector of the West Antarctic Ice Sheet since the Last Glacial Maximum. Quat. Sci. Rev. 100, 55–86 (2014)
Dutrieux, P. et al. Basal terraces on melting ice shelves. Geophys. Res. Lett. 41, 5506–5513 (2014)
Whitehouse, P. L., Bentley, M. J., Milne, G. A., King, M. A. & Thomas, I. D. A new glacial isostatic adjustment model for Antarctica: calibrated and tested using observations of relative sea-level change and present-day uplift rates. Geophys. J. Int. 190, 1464–1482 (2012)
Graham, A. G. C. et al. Submarine glacial-landform distributions across the West Antarctic margin, from grounding line to slope: the Pine Island-Thwaites ice stream system. Geol. Soc. Lond. Mem. 46, 493–500 (2016)
Johnson, J. S. et al. Rapid thinning of Pine Island Glacier in the early Holocene. Science 343, 999–1001 (2014)
Dowdeswell, J. A. & Bamber, J. L. Keel depths of modern Antarctic icebergs and implications for sea-floor scouring in the geological record. Mar. Geol. 243, 120–131 (2007)
Jakobsson, M. et al. Geological record of ice shelf break-up and grounding line retreat, Pine Island Bay, West Antarctica. Geology 39, 691–694 (2011)
Kristoffersen, Y. et al. Seabed erosion on the Lomonosov Ridge, central Arctic Ocean: a tale of deep draft icebergs in the Eurasia Basin and the influence of Atlantic water inflow on iceberg motion? Paleoceanography 19, (2004)
Bentley, M. J. et al. Mechanisms of Holocene palaeoenvironmental change in the Antarctic Peninsula region. Holocene 19, 51–69 (2009)
Scambos, T., Bohlander, J. & Raup, B. Images of Antarctic Ice Shelves (7 November 2009, 3 and 18 November 2013). National Snow and Ice Data Center http://dx.doi.org/10.7265/N5NC5Z4N (1996)
Jakobsson, M. et al. Ice sheet retreat dynamics inferred from glacial morphology of the central Pine Island Bay Trough, West Antarctica. Quat. Sci. Rev. 38, 1–10 (2012)
Duncan, C. S. & Goff, J. A. Relict iceberg keel marks on the New Jersey outer shelf, southern Hudson apron. Geology 29, 411–414 (2001)
Woodworth-Lynas, C. M. T., Josenhans, H. W., Barrie, J. V., Lewis, C. F. M. & Parrott, D. R. The physical processes of seabed disturbance during iceberg grounding and scouring. Cont. Shelf Res. 11, 939–961 (1991)
Gales, J. A., Larter, R. D., Mitchell, N. C. & Dowdeswell, J. A. Geomorphic signature of Antarctic submarine gullies: implications for continental slope processes. Mar. Geol. 337, 112–124 (2013)
Pattyn, F. & Van Huele, W. Power law or power flaw? Earth Surf. Process. Landf. 23, 761–767 (1998)
Burton, J. C. et al. Laboratory investigations of iceberg capsize dynamics, energy dissipation and tsunamigenesis. J. Geophys. Res. Earth Surf. 117, F01007 (2012)
Burton, J. C., Mac Cathles, L. & Wilder, W. G. The role of cooperative iceberg capsize in ice-shelf disintegration. Ann. Glaciol. 54, 84–90 (2013)
Hughes, T. J. West Antarctic ice streams. Rev. Geophys. Space Phys. 15, 1–46 (1977)
Hughes, T. J. On the disintegration of ice shelves: the role of fracture. J. Glaciol. 29, 98–117 (1983)
Benn, D. I., Warren, C. R. & Mottram, R. H. Calving processes and the dynamics of calving glaciers. Earth Sci. Rev. 82, 143–179 (2007)
Nitsche, F. O. et al. Paleo ice flow and subglacial meltwater dynamics in Pine Island Bay, West Antarctica. Cryosphere 7, 249–262 (2013)
Fretwell, P. et al. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375–393 (2013)
Glacial “aftershock” spawns Antarctic iceberg. NASA Earth Observatory Image of the Dayhttps://earthobservatory.nasa.gov/IOTD/view.php?id=89638 (2017)
M.G.W. is funded by a UK Natural Environment Research Council (NERC) PhD studentship (LCAG/247 RG72013) held at the Scott Polar Research Institute, University of Cambridge. The OSO0910 expedition with Swedish icebreaker Oden was carried out as collaboration between the Swedish Polar Research Secretariat, the Swedish Research Council, and the US National Science Foundation (NSF). Part of the data shown in Extended Data Fig. 2 was collected on UK NERC-funded cruise JR179.
The authors declare no competing financial interests.
Reviewer Information Nature thanks T. Scambos 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 figures and tables
Map of iceberg-keel plough marks observed in the study area (n = 10,831). The location of iceberg-keel plough marks in Fig. 2a–c are highlighted in pink, with figure bounds shown by a labelled pink outline. Iceberg-keel plough marks produced during an earlier period of iceberg activity, seaward of a large GZW (the seaward limit of which is shown by a labelled dashed red line)28, are highlighted in blue (n = 30). Observations are limited by data extent and cross-cutting relationships. The inset shows the location of the study area. We note the observation of distinct sets of mega-scale glacial lineations directly seaward and landward of a large GZW, some of which are shown in green. The general area of corrugation ridges (CR) is shown by the dashed yellow outline.
a, Bathymetry42 of inner Pine Island Bay (grid-cell size, 35 m). The Bedmap2-defined calving line43 is shown in yellow. b, Elevation profile of a prominent across-trough bathymetric ridge (red line in a), located about 108 km from the Bedmap2-defined calving line43. Arrows show the location of isolated breaches, interpreted as cross-cutting channels. The blue line shows the estimated ice freeboards, assuming ice was just grounded (in hydrostatic equilibrium) on the ridge surface and was meteoric in density (917 kg m−3). Dashed lines above breaches show the interpolated ice freeboard, if an absence of grounding in the breach itself is assumed.
a–c, The location of the IceBridge transect from flight DC8-100124 (7 November 2009; green line labelled X–X′; analysed in Fig. 3b) is overlaid on NASA MODIS imagery from 7 November 2009 (a), 3 November 2013 (b) and 18 November 2013 (c) available from the NSIDC31 (https://nsidc.org/data/iceshelves_images/index_modis.html). We note the positioning of this transect directly over tabular iceberg B31, which calved from Pine Island Ice Shelf on 13 November 2013. In a and b, the black dashed line shows the landward-most extent of iceberg B31. The floating extent of Pine Island Ice Shelf as defined by Bedmap243 is shown in red.
Extended Data Figure 4 Schematic of iceberg-keel plough marks expected to be produced by tabular icebergs.
Wide, flat-bottomed iceberg-keel plough marks (a) will be produced if iceberg drift is approximately perpendicular to the rugged, ridge-channel underside morphology identified in Fig. 3b. By contrast, if iceberg drift is approximately parallel to the ridge-channel underside morphology, then wide, multi-keeled iceberg plough marks with toothcomb-like morphologies (b) will be produced.
Extended Data Figure 5 Schematic illustration of the cross-sectional dimensions of an iceberg needed to calculate its gravitational potential energy and establish metastable conditions.
H, total thickness of the iceberg; W, width of the iceberg; CM, centre of mass; θ, angle of rotation from an upright (U) to a rotated position (R). The longest axis extends into the page and is not shown. Image adapted from ref. 37, American Geophysical Union.
Extended Data Figure 6 The angle an iceberg 949 m in width (or length) and variable thickness H must be rotated by an external agent to overcome an energy barrier and capsize due to instability (blue curve).
By capsizing, an iceberg width (or length) of 949 m could be transformed into a thickness of equal size. As iceberg thickness decreases, the iceberg becomes increasingly stable and requires a greater angle of rotation about its centre of mass to develop unstable conditions that will cause it to capsize. Calculated from the computations of ref. 37.
Extended Data Figure 7 NASA satellite image of the Pine Island Ice Shelf calving line on 26 January 2017.
The image illustrates the typical planform morphology of icebergs (arrowed) that were calved during the period between the production of large tabular icebergs. With surface areas of 240,000–5,200,000 m2, these icebergs are at most 1% of the size of iceberg B31, which calved from the Pine Island Ice Shelf in November 2013. The largest iceberg (labelled ‘X’ and shaded pink) measures 4,800 m and 1,050 m, in the across- and along-ice-flow directions, respectively. The dashed line overlying a prominent across-ice-flow rift shows the likely calving position of the next large, tabular iceberg. Image adapted from ref. 44, NASA.
About this article
Cite this article
Wise, M., Dowdeswell, J., Jakobsson, M. et al. Evidence of marine ice-cliff instability in Pine Island Bay from iceberg-keel plough marks. Nature 550, 506–510 (2017). https://doi.org/10.1038/nature24458
This article is cited by
Communications Earth & Environment (2022)
Marine ice-cliff instability modeling shows mixed-mode ice-cliff failure and yields calving rate parameterization
Nature Communications (2021)
Acta Oceanologica Sinica (2021)
Nature Geoscience (2020)