Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 3 1 2007 10.5194/cpd-3-221-2007 http://www.clim-past-discuss.net/3/221/2007/ http://www.clim-past-discuss.net/3/221/2007/cpd-3-221-2007.html http://www.clim-past-discuss.net/3/221/2007/cpd-3-221-2007.pdf 221 247 2007-01-26 Modelling the Early Weichselian Eurasian Ice Sheets: role of ice shelves and influence of ice-dammed lakes V. Peyaud peyaud@lgge.obs.ujf-grenoble.fr C. Ritz G. Krinner Laboratoire de Glaciologie et de Géophysique de l'Environnement, Université Joseph Fourier 54, rue Molière, Domaine Universitaire, BP 96, 38402 Saint Martin d'Hères Cedex, France During the last glaciation, a marine ice sheet repeatedly appeared in Eurasia. The floating part of this ice sheet was essential to its rapid extension over the seas. During the earliest stage (90 kyr BP), large ice-dammed lakes formed south of the ice sheet. These lakes are believed to have cooled the climate at the margin of the ice. Using an ice sheet model, we investigated the role of ice shelves during the inception and the influence of ice-dammed lakes on the ice sheet evolution. Inception in Barents sea seems due to thickening of a large ice shelf. We observe a substantial impact of the lakes on the evolution of the ice sheets. Reduced summer ablation enhances ice extent and thickness, and the deglaciation is delayed by 2000 years. Charbit, S., Ritz, C., and Ramstein, G.: Simulations of northern hemisphere ice-sheet retreat: sensitivity to physical mechanisms involved during the Last Deglaciation, Quat. Sci. Rev., 21, 243–265, 2002. Clarke, G K., Leverington, D., Teller, J., and Dyke, A.: Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8200~BP cold event, Quat. Sci. Rev., 23, 399–407, 2004. Fortuin, J. P F. and Oerlemans, J.: Parametrisation of the annual surface temperature and mass balance of Antarctica, Ann. Glaciol., 14, 78–84, 1990. Houmark-Nielse, M., Demidov, I., Funder, S., Grösfjeld, K., Kjǽr, K H., Larsen, E., Lavrova, N., Lyså, A., and Nielsen, J K.: Early and Middle Waldaian glaciations, ice dammed lakes and periglacial interstadials in the northwest Russia: new evidence from Pyoza River area, Global Planet. Change, 31, 215–237, 2001. Hutter, K.: Theoretical Glaciology, D. Reidel, Norwell, Mass., 1983. Jackson, C S. and Broccoli, A J.: Orbital forcing of Arctic climate: mechanisms of climate response and implication for continental glaciation, Clim. Dyn., 21, 539–557, 2003. Joussaume, S. and Braconnot, P.: Sensitivity of paleoclimate simulation results to season definitions, J. Geophys. Res., 102, 1943–1956, 1997. Kenneally, J. and Hughes, T.: The calving constraints on inception of Quaternary ice sheets, Quat. Int., 95–96, 31 943–31 964, 2002. Krinner, G. and Genthon, C.: Altitude dependance of the ice sheet surface climate, Geophys. Res. Lett., 26, 2227–2230, 1999. Krinner, G., Mangerud, J., Jakobsson, M., Crucifix, M., Ritz, C., and Svendsen, J.: Enhanced ice sheet growth in Eurasia owing to adjacent ice-dammed lakes, Nature, 427, 429–432, 2004. Krinner, G., Magand, O., Simmonds, I., Genthon, C., and Dufresne, J.-L.: Simulated Antarctic precipitation and surface mass balance at the end of the twentieth and twenty-first centuries, Clim. Dyn., 28, 215–230, \doi10.1007/s00382-006-0177-x, 2007. Le~Meur, E. and Huybrechts, P.: A comparison of the different ways of dealing with isostasy: examples from modelling the Antartic ice sheet during the last glacial cycle., Ann. Glaciol., 23, 309–317, 1996. MacAyeal, D R.: Large Scale ice flow over a vicous basal Sediment: Theory and Application to Ice Stream B, Antarctica, J. Geophys. Res., 94, 4071–4087, 1989. Mangerud, M., Jakobsson, M., Alexanderson, H., Astakhov, V., Clarke, G. K C., Henriksen, M., Hjort, C., Krinner, G., Lunkka, J.-P., M�ler, P., Muray, A., Nikolskaya, O., Saarnisto, M., and Svendsen, J I.: Ice-dammed lakes and rerouting of the drainage of northern Eurasia during the Last Glaciation, Quat. Sci. Rev., 23, 1331–1332, 2004. Morland, L.: Thermo-mechanical balances of ice sheet flow, Geophys. Astrophys. Fluid Dyn., 29, 237–266, 1984. Oppenheimer, M.: Global warming and the stability of the West Antarctic Ice Sheet, Nature, 393, 325–332, 1998. Paillard, D., Labeyrie, L., and Yiou, P.: Macintosh Program Performs Time-Series Analysis, in: EOS Transactions, vol 77, p. 379, AGU, 1996. Reeh, N.: Parametrization of melt rate and surface temperature on the Greenland ice-sheet, Polarforschung, 59, 113–128, 1991. Ritz, C., Rommeleare, V., and Dumas, C.: Modeling the evolution of Antarctic ice sheet over the last 420,000 years: Implications for altitude changes in the Vostok region, J. Geophys. Res., 106, 31 943–31 964, 2001. Rommelaere, V. and Ritz, C.: A thermomechanical model of ice-shelf flow, Ann. Glaciol., 23, 13–20, 1996. Ruddiman, W F. and McIntyre, A.: Oceanic Mechanisms for Amplification of the 23,000-Year Ice-Volume Cycle, Science, 212, 617–627, 1981. Shackleton, N., Berger, A., and Peltier, W.: An alternative astronomical calibration of the lower Pleistocene timescale based on ODP Site 677, Trans. R. Soc. Edinb. Earth sci., 81, 251–261, 1990. Shapiro, N M. and Ritzwoller, M H.: Inferring surface heat flux distributions guided by a global seismic model: particular application to Antarctica, Earth Planet. Sci. Lett., 223, 213–224, 2004. Siegert, M., Dowdeswell, J A., Hald, M., and Svendsen, J.-I.: Modelling the Eurasian Ice Sheet through a full (Weichselian) glacial cycle, Global Planet. Change, 31, 367–385, 2001. Spielhagen, R., Bonani, G., Eisenhauer, A., Frank, M., Frederichs, T., Kassens, H., Kubik, P., Mangini, A., Norgaard-Pedersen, N., Nowaczyk, N., Schaper, S., Stein, R., Thiede, J., Tiedemann, R., and Wahsner, M.: Arctic Ocean evidence for Late Quaternary initiation of northern Eurasian ice sheets, Geology, 25, 783–786, 1997. Svendsen, J I., Alexanderson, H., Astakhov, V., Demidov, I., Dowdeswell, J., Funder, S., Gataullin, V., Henriksen, M., Hjort, C., Houmark-Nielsen, M., Hubberten, H., Ingiólfsson, \`O., Jakobsson, M., Kjǽr, K., Larsen, E., Lokrantz, H., Lunkka, J.-P., Lyså, A., Mangerud, J., Matiouchkov, A., Murray, A., Möller, P., Niessen, F., Nikolskaya, O., Polyak, L., Saarnisto, M., Siegert, C., Siegert, M. J., Spielhagen, R. S., and Stein, R.: Late Quaternary ice sheet history of Northern Eurasia, Quat. Sci. Rev., 23, 1229–1271, 2004. Vieli, A., Funk, M., and Blatter, H.: Flow dynamics of tidewater glaciers: a numerical modelling approach, J. Glaciol., 47, 595–606, 2001. Wessel, P. and Smith, W. H F.: Free software helps map and display data, EOS Trans. AGU, 72, 441, 1991. Zweck, C. and Huybrechts, P.: Modeling of the northern hemisphere ice sheets during the last glacial cycle and glaciological sensitivity, J. Geophys. Res., 110, L18 402, doi:10.1029/2004JD005489, 2005.