Recent publications/pre-prints by Lev Tarasov

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Sporadically updated publications list for Lev Tarasov

Benoit S. Lecavalier and Lev Tarasov. A history-matching analysis of the Antarctic Ice Sheet since the last interglacial – Part 1: Ice sheet evolution, submitted to Climates of the Past: preprint under discussion and open review .

Matthew Drew and Lev Tarasov. North American Pleistocene Glacial Erosion and Thin Pliocene Regolith Thickness Inferred from Data-Constrained Fully Coupled Ice-Climate-Sediment Modelling, submitted to Climates of the Past: preprint under discussion and open review .

Kevin Hank and Lev Tarasov. The comparative role of physical system processes in Hudson Strait ice stream cycling: a comprehensive model-based test of Heinrich event hypotheses, submitted to Climates of the Past: preprint under discussion and open review .

A. Reyes AV, A. Carlson, J. Clark, L. Guillaume, G. Milne, L. Tarasov, E. Clarlson, F. He, M. Caffee, K. Wilcken, and D. Rood. Timing of Cordilleran-Laurentide ice-sheet separation: implications for sea-level rise; Quaternary Science Reviews: 2024 .

Crow, B. R., L. Tarasov, M. Schulz and M. Prange. Uncertainties originating from GCM downscaling and bias correction with application to the MIS-11c Greenland Ice Sheet, Climates of the Past: 2024 .

April Dalton, Martin Margold, Helen Dulfer, Sophie Norris, and Lev Tarasov. Response of North American ice sheets to the Younger Dryas cold reversal (12.9 to 11.7 ka). submitted to Earth Science Reviews. Under review.

Soran Parang, Glenn A. Milne, Maryam Yousefi, Ryan Love, and Lev Tarasov. Constraining Models of Glacial Isostatic Adjustment in Eastern North America. Submitted to QSR. Under review.

Ryan Love, Glenn A. Milne, Parviz Ajourlou, Soran Parang, Lev Tarasov, and Konstantin Latychev. A Fast Surrogate Model for 3D-Earth Glacial Isostatic Adjustment using Tensorflow (v2.8.10) Artificial Neural Networks, submitted to GMD: preprint under discussion and open review .

Love, R., L. Tarasov, H. Andres, A. Condron, X. Zhang, and G. Lohmann. Exploring the climate system response to a range of freshwater representations: Hosing, Regional, and Freshwater Fingerprints, submitted to Climates of the Past: preprint under discussion and open review .

Kevin Hank, Lev Tarasov, and Elisa Mantell. Modeling sensitivities of thermally and hydraulically driven ice stream surge cycling, Geoscientific Model Development: 2023 .

Matthew Drew and Lev Tarasov. Surging of a Hudson Strait Scale Ice Stream: Subglacial hydrology matters but the process details mostly do not, The Cryosphere: 2023 .

Benoit S. Lecavalier, Lev Tarasov, Greg Balco, Perry Spector, Claus-Dieter Hillenbrand, Christo Buizert, Catherine Ritz, Marion Leduc-Leballeur, Robert Mulvaney, Pippa L. Whitehouse, Michael J. Bentley, and Jonathan Bamber. Antarctic ice sheet paleo-constraint database, Earth System Science Data: 2023 .

Lev Tarasov and Michael Goldstein. Assessing uncertainty in past ice and climate evolution : overview, stepping-stones, and challenges, current version , 2022. This version was rejected by a CP editor for being too long. Original 2021 CPD submission and reviews. Our detailed response to the reviewers. For clearly defined audiences, we selective introduce Bayesian inference, show how it can be effectively useless if uncertainties are not adequately addressed, and suggest ways to move forward.

Frick, Maximilian and Cacace, Mauro and Klemann, Volker and Tarasov, Lev and Scheck-Wenderoth, Magdalena. Hydrogeologic and Thermal Effects of Glaciations on the Intracontinental Basins in Central and Northern Europe, Frontiers in Water online article, 2022.

I. Malmierca-Vallet, L.C. Sime,..,Lev Tarasov,... Dansgaard-Oeschger events in climate models: Review and baseline MIS3 protocol, submitted to Climates of the Past/EGUsphere: preprint under discussion and open review .

W. Colgan, H. Henriksen, O. Bennike,.., L Tarasov, ... Sea-level rise in Denmark: paleo context, recent projections and policy implications, GEUS Bulletin 49, online article, 2022.

Yuchen Sun, Gregor Knorr, Xu Zhang, Lev Tarasov, Stephen Barker, Martin Werner, and Gerrit Lohmann. Ice sheet decline and rising atmospheric CO2 control AMOC sensitivity to deglacial meltwater discharge, GPC 210, online article, 2022.

Claude Hillaire-Marcel, Paul G. Myers, Shawn Marshall, Lev Tarasov, Karl Purcell, Christelle Not, and Anne De Vernal. Challenging the hypothesis of an Arctic Ocean lake during recent glacial episodes, J. Quat. Sci. 37(4), online article, 2022.

Jorie Clark, Anders E. Carlson, Alberto V. Reyes, .., Lev Tarasov, ... The age of the opening of the Ice-Free Corridor and implications for the peopling of the Americas, PNAS 119(14), online article, 2022.

Reyes AV, Carlson AE, Milne GA, Tarasov L, Reimink JR, Caffee MW. Revised chronology of northwest Laurentide ice-sheet deglaciation from 10Be exposure ages on boulder erratics. Quaternary Science Reviews 277:107369, online article, 2022.

Sophie L. Norris, Lev Tarasov, Alistair J. Monteath, John C. Gosse, Alan J. Hidy, Martin Margold, Duane G. Froese. Rapid retreat of the southwestern Laurentide Ice Sheet during the Bølling-Allerød interval, Geology 50(4), online article, 2022.

Ryan Love, Heather Andres, Alan Condron and Lev Tarasov. Freshwater routing in eddy-permitting simulations of the last deglacial: the impact of realistic freshwater discharge. CP, online article, 2021.

Tamsin Edwards, Sophie Nowicki, and many others including Lev Tarasov. land ice contributions to twenty-first-century sea level rise, Nature 15, 593, 74+, online article, 2021.

Kierulf, H. P., Steffen, H., Barletta, V. R., Lidberg, M., Johansson, J., Kristiansen, O., and Tarasov, L.: A GNSS velocity field for geophysical applications in Fennoscandia, J. of Geodyn., 146, online article, 2021.

Anthony Payne, Sophie Nowicki, and many others including Lev Tarasov. Future Sea Level Change Under Coupled Model Intercomparison Project Phase 5 and Phase 6 Scenarios From the Greenland and Antarctic Ice Sheets, GRL, 48, online article, 2021.

Taimaz Bahadory, Lev Tarasov, and Heather Andres. Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling. CP, online article, 2021.

Laurie C. Menviel, Luke C. Skinner, Lev Tarasov, and Polychronis C. Tzedakis. An ice–climate oscillatory framework for Dansgaard–Oeschger cycles. Nature Reviews, online article, 2020.

H. Goelzer, S. Nowicki, ..., L. Tarasov, ... (over 40 authors in total). The future sea-level contribution of the Greenland ice sheet: a multi-model ensemble study of ISMIP6. The Cryosphere, online article, 2020.

April S. Dalton, Martin Margold, Chris R. Stokes, Lev Tarasov, Arthur S. Dyke, and many others... An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex. QSR, online article, 2020.

Joseph Kuchar, Glenn Milne, Alexander Hill, Lev Tarasov, and Maaria Nordman. An investigation into the sensitivity of postglacial decay times to uncertainty in the adopted ice history. Geoph. J. Int, online article, 2020.

Holger Steffen, Rebekka Steffen, and Lev Tarasov. Modelling of glacially-induced stress changes in Latvia, Lithuania and the Kaliningrad District of Russia. BALTICA vol 32, no. 1, online article, 2019.

J.L. Wadham, J.R. Hawkings, L. Tarasov, L.J. Gregoire, R.G.M. Spencer, M. Gutjahr, A. Ridgwell, and K.E. Kohfeld. Ice sheets matter for the global carbon cycle. Nat. Comm., open access online article, 2019.

Heather Andres and Lev Tarasov. Towards understanding potential atmospheric contributions to abrupt climate changes: Characterizing changes to the North Atlantic eddy-driven jet over the last deglaciation, Clim. of the Past, open access online article, 2019.

L. Menviel, E. Capron, A. Govin, A. Dutton, L. Tarasov, et al. The penultimate deglaciation: protocol for PMIP4 transient numerical simulations between 140 and 127 ka, Geosci. Model Devel., open access online article, 2019.

Olave Vestol, Jonas Agren, Holger Steffen, Halfdan Kierulf, and Lev Tarasov. NKG2016LU: a new land uplift model for Fennoscandia and the Baltic Region, Journal of Geodesy, online article, 2019.

Taimaz Bahadory and Lev Tarasov. LCice 1.0: A generalized Ice Sheet Systems Model coupler for LOVECLIM version 1.3: description, sensitivities, and validation with the Glacial Systems Model. Geosci. Model Dev., open access online article, 2018.

Mark Kavanagh, and Lev Tarasov: BrAHMs V1.0: A fast, physically-based subglacial hydrology model for continental-scale application, Geosci. Model Dev., , 2018

Anders E. Carlson, Lev Tarasov , and Tamara Pico. Rapid Laurentide ice-sheet advance towards southern last glacial maximum limit during marine isotope stage 3. Quaternary Science Reviews 196,, 2018.

Maryam Yousefi, Glenn A. Milne, Ryan Love, and Lev Tarasov. Glacial isostatic adjustment along the Pacific coast of central North America 193,, 2018.

Shepherd, A. and the IMBIE team; Mass balance of the Antarctic Ice Sheet from 1992 to 2017, Nature, 558, pages 219-222, 2018.

Frederik Schenk, Minna Valiranta, Francesco Muschitiello, Lev Tarasov, Maija Heikkila, Svante Bjorck, Jenny Brandefelt, Arne V. Johansson, Jens-Ove Naslund, and Barbara Wohlfarth; Warm summers during the Younger Dryas cold reversal, Nature Communications, 9(1), 2041-1723, doi:10.1038/s41467-018-04071-5,, 2018.

Paul J. Morris, Graeme T.Swindels, Paul J. Valdes, Ruza Ivanovic, Lauren Gregoire, Mark Smith, Lev Tarasov, Alan Haywood, and Karen Bacon. Peat initiation triggered by regionally-asynchronous warming. Proc. Nat. Ac. of Sci., 2018.

Kageyama, M. and Braconnot, P. and Harrison, S. P. and Haywood, A. M. and Jungclaus, J. and Otto- Bliesner, B. L. and Peterschmitt, J.-Y. and Abe-Ouchi, A. and Albani, S. and Bartlein, P. J. and Brierley, C. and Crucifix, M. and Dolan, A. and Fernandez-Donado, L. and Fischer, H. and Hopcroft, P. O. and Ivanovic, R. F. and Lambert, F. and Lunt, D. J. and Mahowald, N. M. and Peltier, W. R. and Phipps, S. J. and Roche, D. M. and Schmidt, G. A. and Tarasov, L. and Valdes, P. J. and Zhang, Q. and Zhou, T.; The PMIP4 contribution to CMIP6 - Part 1: Overview and over-arching analysis plan. Geoscientific Model Development. 1033-1057, 2018.

Joseph Kuchar, Glenn Milne, Martin Wolstencroft, Ryan Love, Lev Tarasov, Marc Hijma. The Influence of Sediment Isostatic Adjustment on Sea-Level Change and Land Motion along the US Gulf Coast. Journal of Geophysical Research: Solid Earth, DOI: 10.1002/2017JB014695, 2018

Lev Tarasov and Joel Finnis. The Climate Consequences of Oil Consumption and Some Societal Implications, in Asking the Big Questions: Reflections on a Sustainable Post Oil-dependent Newfoundland and Labrador,; Ommer, Neis, and Brake ed., 2017

Mohammad Hizbul Bahar Arif, Lev Tarasoff, and Tristan Hauser. The Climate Generator: Stochastic climate representation for glacial cycle integration, Geosci. Model Dev. Discuss.,, 2017

Kageyama, M., Albani, S., Braconnot, P., Harrison, S. P., Hopcroft, P. O., Ivanovic, R. F., Lambert, F., Marti, O., Peltier, W. R., Peterschmitt, J.-Y., Roche, D. M., Tarasov, L., Zhang, X., Brady, E. C., Haywood, A. M., LeGrande, A. N., Lunt, D. J., Mahowald, N. M., Mikolajewicz, U., Nisancioglu, K. H., Otto-Bliesner, B. L., Renssen, H., Tomas, R. A., Zhang, Q., Abe-Ouchi, A., Bartlein, P. J., Cao, J., Li, Q., Lohmann, G., Ohgaito, R., Shi, X., Volodin, E., Yoshida, K., Zhang, X., and Zheng, W.: The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments, Geosci. Model Dev., 10, 4035-4055,, 2017

Benoit S. Lecavalier, David A. Fisher, Glenn A. Milne, Bo M. Vinther, Lev Tarasov, Philippe Huybrechts, Denis Lacelle, Brittany Main, James Zheng, Jocelyne Bourgeois, and Arthur S. Dyke. High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution, PNAS, 114(23), doi:10.1073/pnas.1616287114, 2017.

Kageyama, M. and Braconnot, P. and Harrison, S. P. and Haywood, A. M. and Jungclaus, J. and Otto- Bliesner, B. L. and Peterschmitt, J.-Y. and Abe-Ouchi, A. and Albani, S. and Bartlein, P. J. and Brierley, C. and Crucifix, M. and Dolan, A. and Fernandez-Donado, L. and Fischer, H. and Hopcroft, P. O. and Ivanovic, R. F. and Lambert, F. and Lunt, D. J. and Mahowald, N. M. and Peltier, W. R. and Phipps, S. J. and Roche, D. M. and Schmidt, G. A. and Tarasov, L. and Valdes, P. J. and Zhang, Q. and Zhou, T.(2017). PMIP4- CMIP6: the contribution of the Paleoclimate Modelling Intercomparison Project to CMIP6. Geoscientific Model Development Discussions. 2016: 1-46.

Hugo Beltrami, Gurpreet S. Matharoo, Jason E. Smerdon, Lizett Illanes, and Lev Tarasov. Impacts of the Last Glacial Cycle on ground surface temperature reconstructions over the last millennium, Geophys. Res. Lett., 43, doi:10.1002/2016GL071317, 2016.

Ryan Love, Glenn A.Milne, Lev Tarasov, Simon E. Engelhart, Marc P. Hijma, Konstantin Latychev, Benjamin P. Horton, and Torbjorn E. Tornqvis. The contribution of glacial isostatic adjustment to projections of sea-level change along the Atlantic and Gulf coasts of North America, Earth's Future,4, 440-464, doi:10.1002/2016EF000363, 2016. online article.

Ruza F. Ivanovic, Lauren J. Gregoire, Masa Kageyama, Didier M. Roche, Paul J. Valdes, Andrea Burke, Rosemarie Drummond, W. Richard Peltier, and Lev Tarasov. Transient climate simulations of the deglaciation 21-9 thousand years before present; PMIP4 Core experiment design and boundary conditions, Geosci. Model Dev., 9, 2563-2587, doi:10.5194/gmd-9-2563-2016, 2016.

Dusterhus, A.; Rovere, A.; Carlson, A. E.; Horton, B. P.; Klemann, V.; Tarasov, L.; Barlow, N. L. M.; Bradwell, T.; Clark, J.; Dutton, A.; Gehrels, W. R.; Hibbert, F. D.; Hijma, M. P.; Khan, N.; Kopp, R. E.; Sivan, D.; Tornqvist, T. E.: Palaeo-sea-level and palaeo-ice-sheet databases: problems, strategies, and perspectives, Climate of the Past, 12, 911-921, doi:10.5194/cp-12-911-2016.

Chris Stokes, Martin Margold, Chris D. Clark, and Lev Tarasov. Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation. Nature, vol 530, doi:10.1038/nature16947, 2016.

Abe-Ouchi, A., Saito, F., Kageyama, M., Braconnot, P., Harrison, S. P., Lambeck, K., Otto-Bliesner, B. L., Peltier, W. R., Tarasov, L., Peterschmitt, J.-Y., and Takahashi, K.: Ice-sheet configuration in the CMIP5/PMIP3 Last Glacial Maximum experiments, Geosci. Model Dev., 8, 3621-3637, 2015. online article.

Jerome Goslin, Brigitte Van Vliet Lanoe, Giorgio Spada, Sarah Bradley, Lev Tarasov, Simon Neill, Serge Suanez. A new Holocene relative sea-level curve for western Brittany (France): Insights on isostatic dynamics along the Atlantic coasts of north-western Europe. Quaternary Science Reviews 129, 341-365,, 2015.

K. Le Morzadec, L. Tarasov, M. Morlighem, and H. Seroussi. A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: validation and last glacial cycle, GMD, 8, 3199-3213, doi:10.5194/gmd-8-3199-2015, 2015.

Chris R Stokes; Lev Tarasov; Robin Blomdin; Thomas M Cronin; Timothy G Fisher; Richard Gyllencreutz; Clas Hättestrand; Jakob Heyman; Richard Hindmarsh; Anna Hughes; Martin Jakobsson; Nina Kirchner; Stephen J Livingstone; Martin Margold; Julian Murton; Riko Noormets; Richard W Peltier; Dorothy M Peteet; David Piper; Frank Preusser; Hans Renssen; Dave H Roberts; Didier Roche; Francky Saint-Ange; Arjen P Stroeven; James T Teller. On the Reconstruction of Palaeo-Ice Sheets: Recent Advances and Future Challenges. Quaternary Science Reviews, vol 125, p 15-49, doi:10.1016/j.quascirev.2015.07.016, 2015.

Stephen Livingstone; Robert D Storrar; John K Hillier; Chris R Stokes; Chris D Clark; Lev Tarasov. An ice-sheet scale comparison of eskers with modelled subglacial drainage routes, Geomorphology, pp. 104-112, 10.1016/j.geomorph.2015.06.016, 2015.

Bart Root, Lev Tarasov, and Wouter van der Wal. GRACE gravity observations constrain Weichselian ice thickness in the Barents Sea, GRL, DOI: 10.1002/2015GL063769, 2015.

Maaria Nordman, Glenn Milne, Lev Tarasov. Reappraisal of the Angerman River decay time estimate and its application to determine uncertainty in Earth viscosity structure, Geophysical J. Int., 201, 811–822, doi: 10.1093/gji/ggv051, 2015.

Peter U. Clark and Lev Tarasov. Closing the sea level budget at the Last Glacial Maximum. PNAS Commentary, 111(45), 15861-15862; doi:10.1073/pnas.1418970111, 2014.

Robert Briggs, David Pollard, and Lev Tarasov. A data constrained large ensemble analysis of Antarctic evolution since the Eemian, Quaternary Science Reviews, 103, 91-115, 2014.

Benoit S. Lecavalier, Glenn A. Milne, Matthew J.R. Simpson, Leanne Wake, Philippe Huybrechts, Lev Tarasov, Kristian K. Kjeldsen, Svend Funder, Antony J. Long, Sarah Woodroffe, Arthur S. Dyke Nicolaj K. Larsen. A model of Greenland ice sheet deglaciation constrained by observations of relative sea level and ice extent, Quaternary Science Reviews, 102, 54-84, 2014.

H. Beltrami G. S. Matharoo, L. Tarasov, V. Rath and J. E. Smerdon. Numerical studies on the Impact of the Last Glacial Cycle on recent borehole temperature profiles: implications for terrestrial energy balance, Climate of the Past, 10, 1693–1706, 2014. doi:10.5194/cp-10-1693-2014

Robert Briggs, David Pollard, and Lev Tarasov. A glacial systems model configured for large ensemble analysis of Antarctic deglaciation, The Cryosphere, 2013.

Stephen Livingstone, Chris D. Clark, and Lev Tarasov; Modelling North American palaeo-subglacial lakes and their meltwater drainage pathways, Earth and Plan. Sci. Let., 2013.

Alexandre Melanson, Trevor Bell, and Lev Tarasov; Numerical Modelling of Subglacial Erosion and Sediment Transport and its Application to the North American Ice Sheets over the Last Glacial Cycle, Quaternary Science Reviews, 2013.

Robert Briggs and Lev Tarasov. Evaluating model-derived deglaciation chronologies for Antarctica. Quaternary Science Reviews, 2013.

Chris Stokes, Lev Tarasov, and A.S. Dyke; Dynamics of the North American Ice Sheet Complex during its inception and build-up to the Last Glacial Maximum, Quaternary Science Reviews, 2012.

Lev Tarasov; Arthur S. Dyke, Radford M. Neal, and W.R. Peltier; A data-calibrated distribution of deglacial chronologies for the North American ice complex from glaciological modelling, Earth and Plan. Sci. Let., 2012. revised submission,primary supplement,RSL plots,Tertiary supplement,online article.

Tristan Hauser, Andrew Keats, and Lev Tarasov; Artificial neural network assisted Bayesian calibration of climate models, Clim. Dyn., 2011.supplement,online article.

R. Calov, R. Greve, A. Abe-Ouchi, E. Bueler, P. Huybrechts, J. Johnson, F. Pattyn, D. Pollard, C. Ritz, F. Saito, and L. Tarasov, Results from the Ice-Sheet Model Intercomparison Project-Heinrich Event INtercOmparison (ISMIP HEINO), J. of Glaciology, 56, 371-383, 2010.

K. Westley; T. Bell; M. Renouf; and L. Tarasov, Impact assessment of current and future sea-level change on coastal archaeological resources illustrated examples from northern Newfoundland, J. of Island and Coastal Archaeology, 2010.

R. L. Stotler, S. K. Frape, L. Ahonen; I. D. Clark, S. Greene, M. Hobbs, E. Johnson; J.-M. Lemieux, W. R. Peltier, L. Pratt, T. Ruskeeniemi, E. A Sudicky, and L. Tarasov, Thermogenic Methane Hydrate in a Crystalline Shield, Earth and Plan. Sci. Let. , 296, 384-394, doi:10.1016/j.epsl.2010.05.024, 2010.

Chris Stokes and Lev Tarasov, Ice streaming in the Laurentide Ice Sheet: A first comparison between data- calibrated numerical model output and geological evidence, Geophys. Res. Let., doi:10.1029/2009GL040990, 2010.

J.-M. Lemieux, E. A. Sudicky, W.R. Peltier, L. Tarasov, Simulating the impact of glaciations on continental groundwater flow systems. I. Relevant processes and model formulation, J. Geophys. Res., doi:2007JF000928, 2008.

J.-M. Lemieux, E. A. Sudicky, W.R. Peltier, L. Tarasov, Simulating the impact of glaciations on continental groundwater flow systems. II. Model application to the Wisconsinian glaciation over the Canadian landscape, J. Geophys. Res., doi:2007JF000929, 2008.

J.-M. Lemieux, E. A. Sudicky, W.R. Peltier, L. Tarasov, Dynamics of groundwater recharge and seepage over the Canadian landscape during the Wisconsinian glaciation, J. Geophys. Res, 113, F01011, doi:10.1029/2007JF000838, 2008.


Pleistocene glaciations and their associated dramatic climatic conditions are suspected to have had a large impact on the groundwater flow system over the entire North American continent. Because of the myriad of complex flow-related processes involved during a glaciation period, numerical models have become powerful tools for examining groundwater flow system evolution in this context. In this study, a series of key processes pertaining to coupled groundwater flow and glaciation modeling, such as density- dependent (i.e., brine) flow, hydromechanical loading, subglacial infiltration, isostasy, and permafrost development, are included in the numerical model HydroGeoSphere to simulate groundwater flow over the Canadian landscape during the Wisconsinian glaciation (@120 ka to present). The primary objective is to demonstrate the immense impact of glacial advances and retreats during the Wisconsinian glaciation on the dynamical evolution of groundwater flow systems over the Canadian landscape, including surface-subsurface water exchanges (i.e., recharge and discharge fluxes) in both the subglacial and the periglacial environments. It is shown that much of the infiltration of subglacial meltwater occurs during ice sheet progression and that during ice sheet regression, groundwater mainly exfiltrates on the surface, in both the subglacial and periglacial environments. The average infiltration/exfiltration fluxes range between 0 and 12 mm/a. Using mixed, ice sheet thickness dependent boundary conditions for the subglacial environment, it was estimated that 15 to 70% of the meltwater infiltrated into the subsurface as recharge, with an average of 43%. Considering the volume of meltwater that was generated subsequent to the last glacial maximum, these recharge rates, which are related to the bedrock type and elastic properties, are historically significant and therefore played an immense role in the evolution of groundwater flow system evolution over the Canadian landmass over the last 120 ka. Finally, it is shown that the permafrost extent plays a key role in the distribution of surface-subsurface interaction because the presence of permafrost acts as a barrier for groundwater flow.

L. Tarasov, Meltwater discharge and its dynamical role during the Younger Dryas. Current Research in the Pleistocene. 24, 18-23, 2007.

first paragraph

The original suggestion, by Rooth (1982) and refined by Broecker and al (1989), that the Younger Dryas was due to a reduction or shutdown in the large ocean heat conveyor (thermohaline circulation) triggered by a meltwater flood from eastward diversion of pro-glacial Lake Agassiz outflow, has been widely accepted for over a decade. This hypothesis fit inferred timing for a major reduction of southern outflow via the Mississippi river, as recorded in various paleoceanographic proxies from marine sedimentary cores from the Gulf of Mexico. Furthermore, paleoceanographic evidence for a reduction in the rate of the deep overturning circulation during the YD has become quite robust. However, over the last few years, a number of challenges have arisen. To assess our current understanding, I will address three key issues in turn.

L. Tarasov and W. R. Peltier, The co-evolution of continental ice cover and permafrost extent over the last glacial-interglacial cycle in North America. J. Geophys. Res. vol. 112, F02S08, doi:10.1029/2006JF000661, 2007. pdf


The bed-thermal characteristics of a glacial systems model that has been calibrated against a large set of relative sea-level, geodetic, and strandline observations are examined for the previously glaciated sector of the North American continent. The model compares favourably against the present day extent of permafrost and against the observed temperature profiles from three deep boreholes when appropriate bed-thermal conductivities are employed. Estimates for the present day depth field of the lower permafrost boundary are presented. We find a significant disequilibrium in the lower permafrost boundary for most of the Arctic region, with present-day depth as much as 250 m shallower than the equilibrium value for present day climate forcing. This is largely due to the on-going response to the loss of ice cover from the glacial period.

The time evolution of the sub-glacial warm-based area fraction is also presented together with calibration derived confidence intervals. A peak warm-based fraction of $50\% \pm 6\%$ is obtained at last glacial maximum (LGM). The timing of the three largest ice volume maxima that were produced in response to the obliquity component of orbital forcing during the last glacial cycle matches that of the maxima for the warm-based area fraction with no significant phase delay. Warm-based conditions are required to enable ice streaming (fast flow) in the model. It is therefore hypothesized that the expansion of the area covered by warm-based ice played a critical role in producing a highly dynamic ice-sheet during both the most intense growth and recession phases.

L. Tarasov and W. R. Peltier, A calibrated deglacial drainage chronology for the North American continent: Evidence of an Arctic trigger for the Younger Dryas, Quat. Sci. Rev. vol 25, 659-688, 2006; pdf


We present a new deglacial meltwater drainage chronology for the North American ice sheet complex using a 3D glacial systems model calibrated against a large set of paleo-proxies. Results indicate that North America was responsible for a significant fraction of mwp1-a, with order 1.5 dSv or larger (100 year mean) peak discharges into both the Gulf of Mexico and the Eastern Atlantic and less than 1 dSv into the Arctic Ocean.

Our most significant result concerns discharge into the Arctic Ocean. The largest total discharge into the Arctic Ocean (ensemble mean values of 1.0 to 2.2 dSv) occurs during the onset of the Younger Dryas. The large majority of this discharge is locally sourced with reduction of the Keewatin ice dome being the largest contributor. Given that the only outlet from the Arctic Basin at this time was via Fram Strait into the Greenland-Iceland-Norwegian Seas, we hypothesize that this pulse was the trigger for the re-organization of thermohaline circulation that is thought to have been responsible for the Younger Dryas cold interval. In contradistinction with past inferences and subject to the imperfectly constrained ice-margin chronology, we also find that the Northwest outlet likely dominated much of the post -13 kyr drainage of Lake Agassiz.

L. Tarasov and W. R. Peltier, Arctic freshwater forcing of the Younger Dryas cold reversal, Nature, vol 435, 662-665, 2005; Nature link; supplement (freely available)


The last deglaciation was abruptly interrupted by a millennial-scale reversion to glacial conditions. The cause of this Younger Dryas cold interval has been connected to a decrease in the rate of North Atlantic Deep Water formation and to a resultant weakening of the meridional overturning circulation due to surface freshening. In contrast, the earlier meltwater pulse 1-a event, of disputed provenance, produced no apparent reduction of the meridional overturning circulation. To identify the source of the freshwater forcing that weakened the meridional overturning circulation, we present the analysis of objectively-constrained drainage chronology ensembles for the North American ice-sheet derived from a calibrated Glacial Systems Model. We find that this ice-sheet sourced about half of meltwater pulse 1-a. During the onset of the Younger Dryas, we find that the largest combined meltwater/iceberg discharge was directed into the Arctic Ocean. Given that the only drainage outlet from the Arctic Ocean was via Fram Strait into the Greenland-Iceland-Norwegian Seas, where North Atlantic Deep Water is formed today, we hypothesize that it was this Arctic freshwater flux that triggered the Younger Dryas cold reversal.

L. Tarasov and W. R. Peltier, A geophysically constrained large ensemble analysis of the deglacial history of the North American ice sheet complex, Quat. Sci. Rev. vol 23, 359-388, 2004; pdf


Past reconstructions of the deglaciation history of the North American (NA) ice sheet complex have relied either on largely unconstrained and limited explorations of the phase space of solutions produced by glaciological models or upon geophysical inversions of relative sea level (RSL) data which suffer from incomplete geographic coverage of the glaciated regions, load history amplitude/timing ambiguities, and a lack of a priori glaciological self-consistency. As a first step in the development of a much more highly constrained deglaciation history, we present a synthesis of these two previously disjoint methodologies based on a large ensemble of glacial cycle simulations using a three dimensional thermo-mechanically coupled ice sheet model. Twenty glacial system model parameters, chosen so as to best cover the true deglacial phase space, were varied across the ensemble. Furthermore, a new high-resolution digitized ice margin chronology was imposed on the model in order to significantly limit the uncertainties associated with deglacial climate forcing. The model is simultaneously constrained by a large set of high quality RSL histories, a space geodetic observation of the present day rate of vertical motion of the crust from Yellowknife and a traverse of absolute gravity measurements from the west coast of Hudson Bay southward into Iowa.

The general form of the Last Glacial Maximum (LGM) ice topography that ensues when model results are subject to geophysical constraints is an ice sheet dominated by a large (3.3 to 4.3 km maximum ice thickness) Keewatin dome to the west of Hudson Bay connected to a major ice ridge running southeast to the Great Lakes, together with a Hudson Bay region that has relatively thin ice and an Arctic region heavily incised by open-water and/or ice-shelves. Geographically restricted fast flows due to sub-glacial till-deformation are shown to be critical to obtaining such a multi-domed late glacial Laurentide Ice Sheet structure, one that has been previously inferred on the basis of geomorphological data and that is required to fit the geophysical constraints. Our results further suggest that the NA contribution to LGM eustatic sea level drop is likely to be in the range of 60 to 75 m.

L. Tarasov and W. R. Peltier, Greenland glacial history, borehole constraints and Eemian extent, J. Geophys. Res. vol. 108(B3), 2124-2143, 2003; pdf


We examine the extent to which observations from the Greenland ice sheet combined with 3D dynamical ice sheet models and Semi-Lagrangian tracer methods can be used to constrain inferences of the Eemian evolution of the ice sheet, of the extent and frequency of summit migration during the 100 kyr ice age cycle, and of the deep geothermal flux of heat from the earth into the base of the ice sheet. Relative sea-level, present-day surface geometry, basal temperature, and age and temperature profiles from GRIP are imposed as constraints to tune ice sheet model and climate forcing parameters. Despite the paucity of observations, model-based inferences suggest a significant north-east gradient in geothermal heat flux. Our analyses also suggest that during the glacial cycle, the contemporaneous summit only occupied the present-day location during interglacial periods. Based on the development and use of a high resolution Semi-Lagrangian tracer analysis methodology for del 18 O we rule out isotropic flow disturbances due to summit migration as a possible source of the high Eemian variability of the GRIP del 18 O record. Finally, in contrast with results obtained in some recent attempts to infer the extent to which Greenland may have contributed to the anomalous high stand of Eemian sea-level, we find that conservative bounds for this contribution are 2 to 5.2 m, with a more likely range of 2.7 to 4.5 m.

L. Tarasov and W. R. Peltier, Greenland glacial history and local geodynamic consequences, Geophy. J. Int., vol 150, 198-229, 2002; pdf


Space-time reconstructions of the continental ice-sheets that existed at Last Glacial Maximum(LGM) have previously been produced using two entirely independent methodologies, respectively that based upon the use of theoretical models of ice-sheet accumulation and flow and that based upon the geophysical inversion of relative sea level (RSL) histories from previously ice-covered regions. The analyses described in this paper demonstrate the significant advantages that derive from the simultaneous application of both methods to the particular case of Greenland. We thereby show that the ICE-4G reconstruction of the glaciation history of this region from LGM to present, which was based upon the geophysical inversion of RSL data alone, was reasonably accurate in the peripheral regions where RSL data were available but inaccurate in the interior of the ice-sheet which was unconstrained by such information. We test the new model of Greenland glacial history determined by the simultaneous application of the constraints that derive from ice-sheet modelling and the geophysical inversion of RSL data by employing recently published geodetic inferences of mass-balance over the entire interior region of the ice sheet and of GPS measurements of vertical crustal motion. These observations, which were not employed to constrain the ice-sheet reconstruction, provide significant support for the new glacial history for Greenland that our analyses have led us to infer.

L. Tarasov and W.R. Peltier, Laurentide ice sheet form in Glen flow law based models, Ann. Glac., vol. 30, 177-186, 2000.

W.R. Peltier, D.L. Goldsby, D.L. Kohlstedt, and L. Tarasov, Ice-age ice sheet rheology: constraints from Last Glacial Maximum form of the Laurentide ice sheet, Ann. Glac. , vol. 30, 163-176, 2000.

S.J. Marshall, L. Tarasov, G.K.C. Clarke and W.R. Peltier, Glaciology of Ice Age cycles: Physical processes and modelling challenges, Can. J. Earth Sci., vol. 37, 769-793, 2000.

Payne, A. J. and 10 others, Results from the EISMINT model intercomparison: the effects of thermomechanical coupling, J. Glac., vol. 46, 227-238, 2000.

L. Tarasov and W.R. Peltier, The Impact of Thermo-mechanical Ice sheet Coupling on a Model of the 100 kyr Ice-Age Cycle, J. Geophys. Res., vol. 104, 9517-9545, 1999.

W.T. Hyde, T.J. Crowley, L. Tarasov and W.R. Peltier, The Pangean Ice Age: Studies with a coupled Climate-Ice Sheet Model, Clim. Dyn., vol. 12, 100-115, 1999.

L. Tarasov and W.R. Peltier, A high-resolution model of the 100kyr Ice Age cycle; Ann. Glac., vol. 25, 58-65, 1997.

L. Tarasov and W.R. Peltier, Terminating the 100 kyr Ice Age cycle, J. Geophys. Res., vol. 102, 21665-21693, 1997.

Mann, R.B., L. Tarasov, and A. Zelnikov, Brick walls for black holes, Class. Quant. Grav., vol. 9, 1487-1494, 1992.

Mann, R.B., A. Shiekh, and L. Tarasov, Classical and quantum properties of two-dimensional black holes, Nucl. Phys., vol. B341, 134-154, 1990.

Mann, R.B., L. Tarasov, D.G.C McKeon, and T. Steele, Operator regularization and quantum gravity, Nucl. Phys., vol. B311, 630-672, 1988.

L. Tarasov and R.B. Mann, Shifts of Integration Variable in the Light-Cone Gauge, Modern Phys. Let., vol. A1, 525-533, 1986.

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