TC The Cryosphere TC 1994-0424 Copernicus GmbH Göttingen, Germany 10.5194/tc-4-397-2010 Investigating the sensitivity of numerical model simulations of the modern state of the Greenland ice-sheet and its future response to climate change Stone E. J. 1 Lunt D. J. 1 Rutt I. C. 2 Hanna E. 3 BRIDGE, School of Geographical Sciences, University of Bristol, Bristol, UK School of the Environment and Society, Swansea University, Swansea, UK Department of Geography, University of Sheffield, Sheffield, UK 29 09 2010 4 3 397 417 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.the-cryosphere.net/4/397/2010/tc-4-397-2010.html The full text article is available as a PDF file from http://www.the-cryosphere.net/4/397/2010/tc-4-397-2010.pdf

Ice thickness and bedrock topography are essential boundary conditions for numerical modelling of the evolution of the Greenland ice-sheet (GrIS). The datasets currently in use by the majority of GrIS modelling studies are over two decades old and based on data collected from the 1970s and 80s. We use a newer, high-resolution Digital Elevation Model of the GrIS and new temperature and precipitation forcings to drive the Glimmer ice-sheet model offline under steady state, present day climatic conditions. Comparisons are made of ice-sheet geometry between these new datasets and older ones used in the EISMINT-3 exercise. We find that changing to the newer bedrock and ice thickness makes the greatest difference to Greenland ice volume and ice surface extent. When all boundary conditions and forcings are simultaneously changed to the newer datasets the ice-sheet is 33% larger in volume compared with observation and 17% larger than that modelled by EISMINT-3. <br><br> We performed a tuning exercise to improve the modelled present day ice-sheet. Several solutions were chosen in order to represent improvement in different aspects of the GrIS geometry: ice thickness, ice volume and ice surface extent. We applied these new parameter sets for Glimmer to several future climate scenarios where atmospheric CO<sub>2</sub> concentration was elevated to 400, 560 and 1120 ppmv (compared with 280 ppmv in the control) using a fully coupled General Circulation Model. Collapse of the ice-sheet was found to occur between 400 and 560 ppmv, a threshold substantially lower than previously modelled using the standard EISMINT-3 setup. This work highlights the need to assess carefully boundary conditions and forcings required by ice-sheet models, particularly in terms of the abstractions required for large-scale ice-sheet models, and the implications that these can have on predictions of ice-sheet geometry under past and future climate scenarios.

 References Alley, R. B., Clark, P. U., Huybrechts, P., and Joughin, I.: Ice-Sheet and Sea-Level Changes, Science, 310, 456–460, 2005. Bamber, J. L., Layberry, R. L., and Gogineni, P.: A new ice thickness and bed data set for the Greenland ice-sheet 1 Measurement, data reduction, and errors, J. Geophys. Res., 106, 33773-33780, 2001. Banks, D.: An Introduction to Thermogeology Ground Source Heating and Cooling, Blackwell Publishing Ltd, Oxford, UK, 339~pp., 2008. Bougamont, M., Bamber, J. L., Ridley, J. K., Gladstone, R. M., Greuell, W., Hanna, E., Payne, A. J., and Rutt, I.: Impact of model physics on estimating the surface mass balance of the Greenland ice-sheet, Geophys. Res. Lett., 34, L17501, doi:10.1029/2007GL030700, 2007. Braithwaite, R. J.: Positive degree-day factors for ablation on the Greenland ice-sheet studied by energy-balance modelling, J. Glaciol., 41, 153–160, 1995. Bromwich, D. H., Cullather, R. I., Chen, Q., and Csatho, B. M.: Evaluation of recent precipitation studies for Greenland ice-sheet, J. Geophys. Res.-Atmos., 103, 26007–26024, 1998. Buchardt, S. L. and Dahl-Jensen, D.: Estimating the basal melt rate at NorthGRIP using a Monte Carlo technique, Ann. Glaciol., 45, 137–142, 2007. Burgess, E. W., Forster, R. R., Box, J. E., Mosley-Thompson, E., Bromwich, D. H., Bales, R. C., and Smith, L. C.: A spatially calibrated model of annual accumulation rate on the Greenland Ice Sheet (1958–2007), J. Geophys. Res., 115, F02004, doi:10.1029/2009JF001293, 2010. Calov, R. and Hutter, K.: The thermomechanical response of the Greenland ice-sheet to various climate scenarios, Clim. Dynam., 12, 243–260, 1996. Cuffey, K. M. and Marshall, S. J.: Substantial contribution to sea-level rise during the last interglacial from the Greenland ice-sheet, Nature, 404, 591–594, 2000. Dahl-Jensen, D. and Johnsen, S. J.: Paleotemperatures Still Exist in the Greenland Ice-Sheet, Nature, 320, 250–252, 1986. Dahl-Jensen, D. and Gundestrup, N. S.: Constitutive properties of ice at Dye 3, Greenland, in: The Physical Basis of Ice Sheet Modelling, International Association of Hydrological Sciences Publ., 170, 31–43, 1987. DeConto, R. M. and Pollard, D.: Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO<sub>2</sub>, Nature, 421, 245–249, 2003. Driesschaert, E., Fichefet, T., Goosse, H., Huybrechts, P., Janssens, I., Mouchet, A., Munhoven, G., Brovkin, V., and Weber, S. L.: Modeling the influence of Greenland ice-sheet melting on the Atlantic meridional overturning circulation during the next millennia, Geophys. Res. Lett., 34, L10707, doi:10.1029/2007GL029516, 2007. ECMWF: ECMWF ERA-40 Re-Analysis data, Internet, British Atmospheric Data Centre, 2006: http://badc.nerc.ac.uk/data/ecmwf-e40/, last access: 13~March~2009. Edwards, N. and Marsh, R.: Uncertainties due to transport-parameter sensitivity in an efficient 3-D ocean-climate model, Clim. Dynam., 24, 415–433, 2005. Ekholm, S.: A full coverage, high-resolution topographic model of Greenland computed from a variety of digital elevation data, J. Geophys. Res., 101, 21961–21972, 1996. Essery, R. and Etchevers, P.: Parameter sensitivity in simulations of snowmelt, J. Geophys. Res.-Atmos., 109, D20111, doi:10.1029/2004JD005036, 2004. Ettema, J., Van den Broeke, M. R., Van Meijgaard, E., Van de Berg, W. J., Bamber, J. L., Box, J. E., and Bales, R. C.: Higher surface mass balance of the Greenland ice-sheet revealed by high-resolution climate modeling, Geophys. Res. Lett., 36, L12501, doi:10.1029/2009GL038110, 2009. Fabre, A., Letreguilly, A., Ritz, C., and Mangeney, A.: Greenland under changing climates: sensitivity experiments with a new three-dimensional ice-sheet model, Ann. Glaciol., 21, 1–7, 1995. Fausto, R. S., Ahlstrom, A. P., Van As, D., Boggild, C. E., and Johnsen, S. J.: A new present-day temperature parameterisation for Greenland, J. Glaciol., 55, 95–105, 2009. Fichefet, T., Poncin, C., Goosse, H., Huybrechts, P., Janssens, I., and Le Treut, H.: Implications of changes in freshwater flux from the Greenland ice-sheet for the climate of the 21st~century, Geophys. Res. Lett., 30(17), 1911, doi:10.1029/2003GL017826, 2003. Glover, R. W.: Influence of spatial resolution and treatment of orography on GCM estimates of the surface mass balance of the Greenland ice-sheet, J. Climate, 12, 551–563, 1999. Gordon, C., Cooper, C., Senior, C. A., Banks, H., Gregory, J., Johns, T. C., Mitchell, J. F. B., and Wood, R. A..: The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments, Clim. Dynam., 16, 147-168, 2000. Gregory, J. M. and Huybrechts, P.: Ice-sheet contributions to future sea-level change, Philos. T. Roy. Soc A, 364, 1709–1731, 2006. Greve, R. and Hutter, K.: Polythermal three-dimensional modelling of the Greenland ice-sheet with varied geothermal heat flux, Ann. Glaciol., 21, 8–12, 1995. Greve, R.: On the response of the Greenland ice-sheet to greenhouse climate change, Climatic Change, 46, 289–303, 2000. Greve, R.: Relation of measured basal temperatures and the spatial distribution of the geothermal heat flux for the Greenland ice-sheet, Ann. Glaciol., 42, 424–432, 2005. Grootes, P. M., Stuiver, M., White, J. W. C., Johnsen, S., and Jouzel, J.: Comparison of Oxygen-Isotope Records from the Gisp2 and Grip Greenland Ice Cores, Nature, 366, 552–554, 1993. Hanna, E. and Valdes, P.: Validation of ECMWF (re)analysis surface climate data, 1979–1998, for Greenland and implications for mass balance modelling of the Ice-sheet, Int. J. Climatol., 21, 171–195, 2001. Hanna, E., Huybrechts, P. Janssens, I., Cappelen, J., Steffen, K., and Stephens, A..: Runoff and mass balance of the Greenland ice-sheet: 1958–2003, J. Geophys. Res.-Atmos., 110, D13108, doi:10.1029/2004JD005641, 2005. Hanna, E., McConnell, J., Das, S., Cappelen, J., and Stephens, A.: Observed and modeled Greenland ice-sheet snow accumulation, 1958–2003, and links with regional climate forcing, J. Climate, 19, 344–358, 2006. Hanna, E., Huybrechts, P., Steffen, K., Cappelen, J., Huff, R., Shuman, C., Irvine-Fynn, T., Wise, S., and Griffiths, M..: Increased runoff from melt from the Greenland Ice-sheet: A response to global warming, J. Climate, 21, 331–341, 2008. Hebeler, F., Purves, R. S., and Jamieson, S. S. R.: The impact of parametric uncertainty and topographic error in ice-sheet modelling, J. Glaciol., 54, 899–919, 2008a. Hebeler, F. and Purves, R. S.: The influence of resolution and topographic uncertainty on melt modelling using hypsometric sub-grid parameterization, Hydrol. Process., 22(19), 3965–3979, 2008b. Howat, I. M., Joughin, I., and Scambos, T. A.: Rapid changes in ice discharge from Greenland outlet glaciers, Science, 315, 1559–1561, 2007. Huybrechts, P., Letreguilly, A., and Reeh, N.: The Greenland Ice-Sheet and Greenhouse Warming, Global Planet. Change, 89, 399–412, 1991. Huybrechts, P. and Payne, A. J.: The EISMINT benchmarks for testing-ice-sheet models, Ann. Glaciol., 23, 1–12, 1996. Huybrechts, P.: Report of the Third EISMINT Workshop on Model Intercomparison, Grindelwald, Switzerland, 25–27~September, 1997. Huybrechts, P. and de Wolde, J.: The dynamic response of the Greenland and Antarctic ice-sheets to multiple-century climatic warming, J. Climate, 12, 2169–2188, 1999. IPCC: Climate Change 2007: The Physical Sciences Basis, Contribution of Working Group~I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, Uk and New York, NY, USA, 2007. Janssens, I. and Huybrechts, P.: The treatment of meltwater retention in mass-balance parameterizations of the Greenland ice-sheet, Ann. Glaciol., 31, 133–140, 2000. Johnsen, S. J., Clausen, H. B., Dansgaard, W., Gundestrup, N. S., Hammer, C. U., Andersen, U., Andersen, K. K., Hvidberg, C. S., Dahl-Jensen, D., Steffensen, J. P., Shoji, H., and Sveinbjörnsdóttir, A. E.: The delta O-18 record along the Greenland Ice Core Project deep ice core and the problem of possible Eemian climatic instability, J. Geophys. Res.-Oceans, 102(C12), 26397–26410, 1997. Joughin, I., Abdalati, W., and Fahnestock, M.: Large fluctuations in speed on Greenland's Jakobshavn Isbrae glacier, Nature, 432, 608–610, 2004. Key, J. R., Schweiger, A. J., and Stone, R. S.: Expected uncertainty in satellite-derived estimates of the surface radiation budget at high latitudes, J. Geophys. Res.-Oceans, 102(C7), 15837–15847, 1997. Lambeck, K. and Nakiboglu, S. M.: Seamount Loading and Stress in the Ocean Lithosphere, J. Geophys. Res., 85, 6403–6418, 1980. Lee, W. H. K.: On the global variations of terrestrial heat flow, Phys. Earth Planet. Inter., 2, 332–341, 1970. Lefebre, F., Gallee, H., Van Ypersele, J. P., and Huybrechts, P.: Modelling of large-scale melt parameters with a regional climate model in south Greenland during the 1991 melt season, Ann. Glaciol., 35, 391–397, 2002. Letreguilly, A., Huybrechts, P., and Reeh, N.: Steady-State Characteristics of the Greenland Ice-Sheet under Different Climates, J. Glaciol., 37, 149–157, 1991. Lhomme, N., Clarke, G. K. C., and Marshall, S. J.: Tracer transport in the Greenland Ice-sheet: constraints on ice cores and glacial history, Quaternary Sci. Rev., 24, 173–194, 2005. Luckman, A., Murray, T., de Lange, R., and Hanna, E.: Rapid and synchronous ice-dynamic changes in East Greenland, Geophys. Res. Lett., 33, L03503, doi:10.1029/2005GL025428, 2006. Lunt, D. J., Foster, G. L., Haywood, A. M., and Stone, E. J.: Late Pliocene Greenland glaciation controlled by a decline in atmospheric CO<sub>2</sub> levels, Nature, 454, 1102–1105, 2008. Lunt, D. J., Haywood, A. M., Foster, G. L., and Stone, E. J.: The Arctic cryosphere in the Mid-Pliocene and the future, Philos. T. Roy. Soc A, 367, 49–67, 2009. Marshall, S. J. and Clarke, G. K. C.: Ice sheet inception: subgrid hypsometric parameterization of mass balance in an ice sheet model, Clim. Dynam., 15(7), 533–550, 1999. McKay, M. D., Beckman, R. J., and Conover, W. J.: A Comparison of Three Methods for Selecting Values of Input Variables in the Analysis of Output from a Computer Code, Technometrics, 21, 239–245, 1979. Mikolajewicz, U., Gröger, M., Maier-Reimer, E., Schrgers, G., Vizcaíno, M., and Winguth, A. M. E.: Long-term effects of anthropogenic CO<sub>2</sub> emissions simulated with a complex earth system model, Clim. Dynam., 28, 599–631, 2007. Murphy, C., Fealy, R., Charlton, R., and Sweeney, J.: The reliability of an "off-the-shelf" conceptual rainfall runoff model for use in climate impact assessment: uncertainty quantification using Latin hypercube sampling, Area, 38, 65–78, 2006. NGRIP: High-resolution record of Northern Hemisphere climate extending into the last interglacial period, Nature, 431, 147–151, 2004. Ohmura, A.: New temperature distribution maps for Greenland, Z. Gletscherkd. Glazialgeol., 23, 1–45, 1987. Ohmura, A. and Reeh, N.: New Precipitation and Accumulation Maps for Greenland, J. Glaciol., 37, 140–148, 1991. Parizek, B. R. and Alley, R. B.: Implications of increased Greenland surface melt under global-warming scenarios: ice-sheet simulations, Quaternary Sci. Rev., 23(9–10), 1013–1027, 2004. Parizek, B. R., Alley, R. B., and MacAyeal, D. R.: The PSU/UofC finite-element thermomechanical flowline model of ice-sheet evolution Cold Reg. Sci. Technol., 42, 145–168, 2005. Pattyn, F.: A new three-dimensional higher-order thermomechanical ice-sheet model: Basic sensitivity, ice stream development, and ice flow across subglacial lakes, J. Geophys. Res.-Sol. Ea., 108(B8), 2382, doi:10.1029/2002JB002329, 2003. Pattyn, F., Huyghe, A., De Brabander, S., and De Smedt, B.: Role of transition zones in marine ice-sheet dynamics, J. Geophys. Res.-Earth, 111, F02004, doi:10.1029/2005JF000394, 2006. Payne, A. and Sugden, D.: Topography and Ice-Sheet Growth, Earth Surf. Proc. Land., 15(7), 625–639, 1990. Payne, A. J.: A thermomechanical model of ice flow in West Antarctica, Clim. Dynam., 15, 115–125, 1999. Pollard, D. and Thompson, S. L.: Driving a high-resolution dynamic ice-sheet model with GCM climate: ice-sheet initiation at 116,000 BP, Ann. Glaciol., 25, 296–304, 1997. Price, S. F., Conway, H., Waddington, E. D., and Bindschadler, R. A.: Model investigations of inland migration of fast-flowing outlet glaciers and ice streams, J. Glaciol., 54(184), 49–60, 2008. Reeh, N.: Paramterization of melt rate and surface temperature on the Greenland ice-sheet, Polarforschung, 59, 113–128, 1991. Ridley, J. K., Huybrechts, P., Gregory, J. M., and Lowe, J. A.: Elimination of the Greenland ice-sheet in a high CO<sub>2</sub> climate, J. Climate, 18, 3409–3427, 2005. Rignot, E. and Kanagaratnam, P.: Changes in the velocity structure of the Greenland ice-sheet, Science, 311, 986–990, 2006. Rignot, E., Box, J. E., Burgess, E., and Hanna, E.: Mass balance of the Greenland ice-sheet from 1958 to 2007, Geophys. Res. Lett., 35, L20502, doi:10.1029/2008GL035417, 2008. Ritz, C.: Time dependent boundary conditions for calculation of temperature fields in ice-sheets, in: The Physical Basis of Ice-sheet Modelling, International Association of Hydrological Sciences Publ., 170, 207–216, 1987. Ritz, C., Fabre, A., and Letreguilly, A.: Sensitivity of a Greenland ice-sheet model to ice flow and ablation parameters: Consequences for the evolution through the last climatic cycle, Clim. Dynam., 13, 11–24, 1997. Rutt, I. C., Hagdorn, M., Hulton, N. R. J., and Payne, A. J.: The Glimmer community ice-sheet model, J. Geophys. Res.-Earth, 114, F02004, doi:10.1029/2008JF001015, 2009. Sayag, R. and Tziperman, E.: Spontaneous generation of pure ice streams via flow instability: Role of longitudinal shear stresses and subglacial till, J. Geophys. Res.-Earth, 113, B05411, doi:10.1029/2007JB005228, 2008. Schneider von Deimling, T., Held, H., Ganopolski, A., and Rahmstorf, S.: Climate sensitivity estimated from ensemble simulations of glacial climate, Clim. Dynam., 27, 149–163, 2006. Schoof, C.: A variational approach to ice stream flow, J. Fluid Mech., 556, 227–251, 2006. Schoof, C.: Ice-sheet grounding line dynamics: Steady states, stability, and hysteresis, J. Geophys. Res.-Earth, 112, F03S28, doi:10.1029/2006JF000664, 2007. Serreze, M. C. and Hurst, C. M.: Representation of mean Arctic precipitation from NCEP-NCAR and ERA reanalyses, J. Climate, 13, 182–201, 2000. Serreze, M. C., Barrett, A. P., and Lo, F.: Northern High-Latitude Precipitation as Depicted by Atmospheric Reanalyses and Satellite Retrievals, Mon. Weather Rev., 133, 3407–3430, 2005. Shapiro, N. M. and Ritzwoller, M. H.: Inferring surface heat flux distributions guided by a global seismic model: particular application to Antarctica, Earth Planet. Sc. Lett., 223, 213–224, 2004. Soucek, O. and Martinec, Z.: Iterative improvement of the shallow-ice approximation, J. Glaciol., 54, 812–822, 2008. Steffen, K. and Box, J.: Surface climatology of the Greenland ice-sheet: Greenland Climate Network 1995–1999, J. Geophys. Res., 106(D24), 33951–33964, 2001. Tulaczyk, S., Kamb, W. B., and Engelhardt, H. F.: Basal mechanics of Ice Stream B, West Antarctica 2 Undrained plastic bed model, J. Geophys. Res.-Earth, 105(B1), 483–494, 2000. Uppala, S. M., Kållberg, P. W., Simmons, A. J., Andrae, U., Da Costa Bechtold, V., Fiorino, M., Gibson, J. K., Haseler, J., Hernandez, A., Kelly, G. A., Li, X., Onogi, K., Saarinen, S., Sokka, N., Allan, R. P., Andersson, E., Arpe, K., Balmaseda, M. A., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Caires, S., Chevallier, F., Dethof, A., Dragosavac, M., Fisher, M., Fuentes, M., Hagemann, S., Hólm, E., Hoskins, B. J., Isaksen, L., Janssen, P. A. E. M., Jenne, R., Mcnally, A. P., Mahfouf, J.-F., Morcrette, J.-J., Rayner, N. A., Saunders, R. W., Simon, P., Sterl, A., Trenberth, K. E., Untch, A., Vasiljevic, D., Viterbo, P., and Woollen, J.: The ERA-40 re-analysis, Q. J. Roy. Meteor. Soc., 131, 2961–3013, 2005. van de Wal, R. S. W. and Oerlemans, J.: An Energy-Balance Model for the Greenland Ice-Sheet, Global Planet. Change, 9, 115–131, 1994. van den Broeke, M., Smeets, P., Ettema, J., van der Veen, C., van de Wal, R., and Oerlemans, J.: Partitioning of melt energy and meltwater fluxes in the ablation zone of the west Greenland ice sheet, The Cryosphere, 2, 179–189, doi:10.5194/tc-2-179-2008, 2008. van den Broeke, M., Bamber, J., Ettema, J., Rignot, E., Schrama, E., Jan van de Berg, W., van Meijgaard, E., Velicogna, I., and Wouters, B.: Partitioning Recent Greenland mass Loss, Science, 326, 984–986, 2009. van der Veen, C. J. and Payne, A. J.: Modelling land-ice dynamics, in: Mass Balance of the Cryosphere Observations and Modelling of Contemporary and Future Changes, edited by: Bamber, J. L. and Payne, A. J., Cambridge University Press, Cambridge UK, 169–219, 2004. Velicogna, I.: Increasing rates of ice mass loss from the Greenland and Antarctic ice-sheets revealed by GRACE, Geophys. Res. Lett., 36, L19503, doi:10.1029/2009GL040222, 2009. Vizcaíno, M., Mikolajewicz, U., Gröger, M., Maier-Reimer, E., Schurgers, G., and Winguth, A. M. E..: Long-term ice-sheet-climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth system Model, Clim. Dynam., 31(6), 665–690, doi:10.1007/s00382-008-0369-7, 2008. Wramneby, A., Smith, B., Zaehle, S., and Sykes, M. T.: Parameter uncertainties in the modelling of vegetation dynamics – Effects on tree community structure and ecosystem functioning in European forest biomes, Ecol. Model., 216, 277–290, 2008. Yang, D. Q.: An improved precipitation climatology for the Arctic Ocean, Geophys. Res. Lett., 26, 1625–1628, 1999. Zwinger, T., Greve, R., Gagliardini, O., Shiraiwa, T., and Lyly, M.: A full Stokes-flow thermo-mechanical model for firn and ice applied to the Gorshkov crater glacier, Kamchatka, Ann. Glaciol., 45, 29–37, 2007.