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Plastic bed beneath Hofsjökull Ice Cap, central Iceland, and the sensitivity of ice flow to surface meltwater flux


The mechanical properties of glacier beds play a fundamental role in regulating the sensitivity of glaciers to environmental forcing across a wide range of timescales. Glaciers are commonly underlain by deformable till whose mechanical properties and influence on ice flow are not well understood but are critical for reliable projections of future glacier states. Using synoptic-scale observations of glacier motion in different seasons to constrain numerical ice flow models, we study the mechanics of the bed beneath Hofsjökull, a land-terminating ice cap in central Iceland. Our results indicate that the bed deforms plastically and weakens following incipient summertime surface melt. Combining the inferred basal shear traction fields with a Coulomb-plastic bed model, we estimate the spatially distributed effective basal water pressure and show that changes in basal water pressure and glacier accelerations are non-local and non-linear. These results motivate an idealized physical model relating mean basal water pressure and basal slip rate wherein the sensitivity of glacier flow to changes in basal water pressure is inversely related to the ice surface slope.

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      Plastic bed beneath Hofsjökull Ice Cap, central Iceland, and the sensitivity of ice flow to surface meltwater flux
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This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike licence (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the same Creative Commons licence is included and the original work is properly cited. The written permission of Cambridge University Press must be obtained for commercial re-use.
Corresponding author
Correspondence: B. Minchew <>
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Andrews, LC and 7 others (2014) Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet. Nature, 514, 8083
Bartholomew, I and 5 others (2010) Seasonal evolution of subglacial drainage and acceleration in a Greenland outlet glacier. Nat. Geosci., 3(6), 408411
Björnsson, H (1986) Surface and bedrock topography of ice caps in Iceland mapped by radio echo soundings. Ann. Glaciol., 8, 1118
Björnsson, H (1988) Hydrology of Ice Caps in volcanic regions. Societas Scientarium Islandica, University of Iceland, Reykjavik, Iceland
Björnsson, H and Pálsson, F (2008) Icelandic glaciers. Jökull, 58, 365386
Björnsson, H, Pálsson, F, Sigurðsson, O and Flowers, G (2003) Surges of glaciers in Iceland. Ann. Glaciol., 36, 8290
Blatter, H (1995) Velocity and stress-fields in grounded glaciers: a simple algorithm for including deviatoric stress gradients. J. Glaciol., 41(138), 333344
Bougamont, M and 5 others (2014) Sensitive response of the Greenland Ice Sheet to surface melt drainage over a soft bed. Nat. Commun., 5(5052), 19
Boulton, GS (1979) Processes of glacier erosion on different substrata. J. Glaciol., 23(89), 1537
Cuffey, KM and Paterson, WSB (2010) The physics of glaciers, 4th edn. Elsevier, Burlington, MA, USA
Favier, L and 8 others (2014) Retreat of Pine Island Glacier controlled by marine ice-sheet instability. Nat. Clim. Change, 4, 117121
Fowler, AC (1987) Sliding with cavity formation. J. Glaciol., 33, 255267
Fowler, AC (2000) An instability mechanism for drumlin formation. Geol. Soc. London Special Pub., 176(1), 307319
Fowler, AC (2001). Dunes and Drumlins. In Balmforth, NJ and Provenzale, A eds. Geomorphological fluid mechanics, Springer, Heidelberg, Berlin, vol. 582 of Lecture Notes in Physics, 430454.
Fricker, HA and Scambos, T (2009) Connected subglacial lake activity on lower Mercer and Whillans Ice Streams, West Antarctica, 2003–2008. J. Glaciol., 55(190), 303315
Gudmundsson, GH and Raymond, M (2008) On the limit to resolution and information on basal properties obtainable from surface data on ice streams. Cryosphere, 2(2), 167178
Hensley, S and 5 others (2009) First demonstration results using the NASA/JPL UAVSAR instrument, 2nd Annual Asia Pacific SAR Conference, Xian, China.
Hewitt, IJ (2013) Seasonal changes in ice sheet motion due to melt water lubrication. Earth Planet. Sci. Lett., 371–372, 1625
Hoffman, M and Price, S (2014) Feedbacks between coupled subglacial hydrology and glacier dynamics. J. Geophys. Res., 119, 414436
Iken, A and Bindschadler, R (1986) Combined measurements of subglacial water pressure and surface velocity of Findelengletscher, Switzerland: conclusions about drainage systems and sliding mechanisms. J. Glaciol., 32(110), 101119
Iverson, NR (2010) Shear resistance and continuity of subglacial till: hydrology rules. J. Glaciol., 56(200), 11041114
Iverson, NR, Hooyer, TS and Baker, RW (1998) Ring-shear studies of till deformation: coulomb plastic behavior and distributed strain in glacier beds. J. Glaciol., 44, 634642
Jay-Allemand, M, Gillet-Chaulet, F, Gagliardini, O and Nodet, M (2011) Investigating changes in basal conditions of Variegated Glacier prior to and during its 1982–1983 surge. Cryosphere, 5(3), 659672
Jóhannesson, T and 7 others (2013) Ice-volume changes, bias estimation of mass-balance measurements and changes in subglacial lakes derived by lidar mapping of the surface of Icelandic glaciers. Ann. Glaciol., 54(63), 6374
Johnson, MD and 5 others (2010) Active drumlin field revealed at the margin of Múlajökull, Iceland: a surge-type glacier. Geology, 38(10), 943946
Joughin, I, MacAyeal, D and Tulaczyk, S (2004) Basal shear stress of the Ross ice stream from control method inversions. J. Geophys. Res., 109(B09405), 120
Joughin, I and 5 others (2008) Seasonal speedup along the western flank of the Greenland Ice Sheet. Science, 320(5877), 781783
Joughin, I, Smith, BE and Medley, B (2014) Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica. Science, 344(6185), 735738
Kamb, B (1970) Sliding motion of glaciers: theory and observations. Rev. Geophys., 8(4), 673728
Kamb, B (1987) Glacier surge mechanisms based on linked cavity configuration of the basal water conduit system. J. Geophys. Res., 92(B9), 90839100
Kamb, B (1991) Rheological nonlinearity and flow instability in the deforming-bed mechanism of ice stream motion. J. Geophys. Res.: Solid Earth, 96(B10), 1658516595
Lliboutry, L (1968) General theory of subglacial cavitation and sliding of temperate glaciers. J. Glaciol., 7(49), 2158
MacAyeal, D (1989) Large-scale ice flow over a viscous basal sediment - theory and application to ice stream-B, Antarctica. J. Geophys. Res., 94(B4), 40714087
Magnússon, E, Rott, H, Björnsson, H and Pálsson, F (2007) The impacts of jökulhlaups on basal sliding observed by SAR interferometry on Vatnajökull, Iceland. J. Glaciol., 53(181), 232240
Magnússon, E, Björnsson, H, Rott, H and Pálsson, F (2010) Reduced glacier sliding caused by persistent drainage from a subglacial lake. Cryosphere, 4, 1320
Malvern, LE (1969) Introduction to the mechanics of a continuous medium. Prentice-Hall, Englewood Cliffs, NJ
Minchew, BM, Simons, M, Hensley, S, Björnsson, H and Pálsson, F (2015) Early melt-season velocity fields of Langjökull and Hofsjökull ice caps, central Iceland. J. Glaciol., 61(226), 253266
Moon, T and 6 others (2014) Distinct patterns of seasonal Greenland glacier velocity. Geophys. Res. Lett., 41(20), 72097216
Morlighem, M and 5 others (2010) Spatial patterns of basal drag inferred using control methods from a full-Stokes and simpler models for Pine Island Glacier, West Antarctica. Geophys. Res. Lett., 37(L14502), 16
Morlighem, M, Seroussi, H, Larour, E and Rignot, E (2013) Inversion of basal friction in Antarctica using exact and incomplete adjoints of a higher-order model. J. Geophys. Res.: Earth Surface, 118(3), 17461753
Nye, JF (1970) Glacier sliding without cavitation in a linear viscous approximation. Proc. Roy. Soc. London Ser. A Math. Phys. Sci., 315(1522), 381403
Nye, JF (1976) Water flow in glaciers: jökulhlaups, tunnels and veins. J. Glaciol., 17, 181207
Parizek, BR and Alley, RB (2004) Implications of increased Greenland surface melt under global-warming scenarios: ice-sheet simulations. Quat. Sci. Rev., 23(9–10), 10131027
Pattyn, F (2003) A new three-dimensional higher-order thermo mechanical ice sheet model: basic sensitivity, ice stream development, and ice flow across subglacial lakes. J. Geophys. Res.: Solid Earth, 108(B8), 115
Pimentel, S and Flowers, GE (2011) A numerical study of hydrologically driven glacier dynamics and subglacial flooding. Proc. Roy. Soc. A: Math. Phys. Eng. Sci., 67(2121), 537558
Raymond, C (1996) Shear margins in glaciers and ice sheets. J. Glaciol., 42(140), 90102
Raymond, CF, Benedict, RJ, Harrison, WD, Echelmeyer, KA and Sturm, M (1995) Hydrological discharges and motion of Fels and Black Rapids Glaciers, Alaska, U.S.A.: implications for the structure of their drainage systems. J. Glaciol., 41(138), 290304
Rignot, E and Kanagaratnam, P (2006) Changes in the velocity structure of the Greenland Ice Sheet. Science, 311, 986990
Rosen, PA and 6 others (2000) Synthetic aperture radar interferometry. Proc. IEEE, 88(3), 333382
Röthlisberger, H (1972) Water pressure in intra- and subglacial channels. J. Glaciol., 11, 177203
Schoof, C (2005) The effect of cavitation on glacier sliding. Proc. Roy. Soc. London Ser. A Math. Phys. Sci., 461, 609627
Schoof, C (2007a) Ice sheet grounding line dynamics: Steady states, stability, and hysterisis. J. Geophys. Res., 112(F03S28), 119
Schoof, C (2007b) Pressure-dependent viscosity and interfacial instability in coupled ice-sediment flow. J. Fluid Mech., 570, 227252
Schoof, C (2010) Ice-sheet acceleration driven by melt supply variability. Nature, 468, 803806
Schoof, C and Hindmarsh, RCA (2010) Thin-film flows with wall slip: an asymptotic analysis of higher order glacier flow models. Quart. J. Mech. Appl. Math., 63(1), 73114
Schuenemann, KC and Cassano, JJ (2010) Changes in synoptic weather patterns and Greenland precipitation in the 20th and 21st centuries: 2. Analysis of 21st century atmospheric changes using self-organizing maps. J. Geophys. Res.: Atmos., 115(D5), D05108 (doi: 10.1029/2009JD011706)
Shepherd, A and 5 others (2009) Greenland ice sheet motion coupled with daily melting in late summer. Geophys. Res. Lett., 36(1), L01501
Sugiyama, S and Gudmundsson, GH (2004) Short-term variations in glacial flow controlled by subglacial water pressure at Lauteraar gletscher, Bernese Alps, Switzerland. J. Glaciol., 50(170), 353362
Sundal, AV and 5 others (2011) Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage. Nature, 469(7331), 521524
Tedstone, AJ and 6 others (2013) Greenland ice sheet motion insensitive to exceptional meltwater forcing. Proc. Natl. Acad. Sci., 110(49), 1971919724
Tedstone, AJ and 5 others (2015) Decadal slowdown of a land-terminating sector of the Greenland Ice Sheet despite warming. Nature, 526(7575), 692695
Thompson, J, Simons, M and Tsai, VC (2014) Modeling the elastic transmission of tidal stresses to great distances inland in channelized ice streams. Cryosphere, 8(6), 20072029
Tsai, VC, Stewart, AL and Thompson, AF (2015) Marine ice-sheet profiles and stability under Coulomb basal conditions. J. Glaciol., 61(226), 205215
Tulaczyk, S, Kamb, WB and Engelhardt, HF (2000a) Basal mechanics of Ice Stream B, west Antarctica: 1. Till mechanics. J. Geophys. Res.: Solid Earth, 105(B1), 463481
Tulaczyk, S, Kamb, WB and Engelhardt, HF (2000b) Basal mechanics of Ice Stream B, west Antarctica: 2. Undrained plastic bed model. J. Geophys. Res.: Solid Earth, 105(B1), 483494
Weertman, J (1957) On the sliding of glaciers. J. Glaciol., 3(21), 3338
Werder, MA, Hewitt, IJ, Schoof, CG and Flowers, GE (2013) Modeling channelized and distributed subglacial drainage in two dimensions. J. Geophys. Res.: Earth Surface, 118, 119
Zwally, HJ and 5 others (2002) Surface melt-induced acceleration of Greenland Ice-Sheet flow. Science, 297(5579), 218222
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