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Deglacial rapid sea level rises caused by ice-sheet saddle collapses


The last deglaciation (21 to 7 thousand years ago) was punctuated by several abrupt meltwater pulses, which sometimes caused noticeable climate change1,2. Around 14 thousand years ago, meltwater pulse 1A (MWP-1A), the largest of these events, produced a sea level rise of 14–18 metres over 350 years3. Although this enormous surge of water certainly originated from retreating ice sheets, there is no consensus on the geographical source or underlying physical mechanisms governing the rapid sea level rise4,5,6. Here we present an ice-sheet modelling simulation in which the separation of the Laurentide and Cordilleran ice sheets in North America produces a meltwater pulse corresponding to MWP-1A. Another meltwater pulse is produced when the Labrador and Baffin ice domes around Hudson Bay separate, which could be associated with the ‘8,200-year’ event, the most pronounced abrupt climate event of the past nine thousand years7. For both modelled pulses, the saddle between the two ice domes becomes subject to surface melting because of a general surface lowering caused by climate warming. The melting then rapidly accelerates as the saddle between the two domes gets lower, producing nine metres of sea level rise over 500 years. This mechanism of an ice ‘saddle collapse’ probably explains MWP-1A and the 8,200-year event and sheds light on the consequences of these events on climate.

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Figure 1: The deglaciation of North America.
Figure 2: MWP-1A in model and data.
Figure 3: Mechanism of saddle collapse.
Figure 4: The 8,200-year event in our model.


  1. Clark, P. U. Freshwater forcing of abrupt climate change during the last glaciation. Science 293, 283–287 (2001)

    Article  ADS  CAS  PubMed  Google Scholar 

  2. Bond, G. et al. Correlations between climate records from North-Atlantic sediments and Greenland ice. Nature 365, 143–147 (1993)

    Article  ADS  Google Scholar 

  3. Deschamps, P. et al. Ice-sheet collapse and sea-level rise at the Bolling warming 14,600 years ago. Nature 483, 559–564 (2012)

    Article  ADS  CAS  PubMed  Google Scholar 

  4. Carlson, A. E. Geochemical constraints on the Laurentide Ice Sheet contribution to meltwater pulse 1A. Quat. Sci. Rev. 28, 1625–1630 (2009)

    Article  ADS  Google Scholar 

  5. Clark, P. U., Mitrovica, J. X., Milne, G. A. & Tamisiea, M. E. Sea-level fingerprinting as a direct test for the source of global meltwater pulse IA. Science 295, 2438–2441 (2002)

    ADS  CAS  PubMed  Google Scholar 

  6. Tarasov, L., Dyke, A. S., Neal, R. M. & Peltier, W. R. A data-calibrated distribution of deglacial chronologies for the North American ice complex from glaciological modeling. Earth Planet. Sci. Lett. 315–316, 30–40 (2012)

    Article  ADS  Google Scholar 

  7. Barber, D. C. et al. Forcing of the cold event of 8,200 years ago by catastrophic drainage of Laurentide lakes. Nature 400, 344–348 (1999)

    Article  ADS  CAS  Google Scholar 

  8. Dyke, A. S. An outline of North American deglaciation with emphasis on central and northern Canada. Dev. Quat. Sci. 2, 373–424 (2004)

    Google Scholar 

  9. Thornalley, D. J. R., McCave, I. N. & Elderfield, H. Freshwater input and abrupt deglacial climate change in the North Atlantic. Paleoceanography 25, PA1201 (2010)

    ADS  Google Scholar 

  10. Aharon, P. Entrainment of meltwaters in hyperpycnal flows during deglaciation superfloods in the Gulf of Mexico. Earth Planet. Sci. Lett. 241, 260–270 (2006)

    Article  ADS  CAS  Google Scholar 

  11. Stanford, J. D. et al. Timing of meltwater pulse 1a and climate responses to meltwater injections. Paleoceanography 21, PA4103 (2006)

    Article  ADS  Google Scholar 

  12. Menviel, L., Timmermann, A., Timm, O. E. & Mouchet, A. Deconstructing the Last Glacial termination: the role of millennial and orbital-scale forcings. Quat. Sci. Rev. 30, 1155–1172 (2011)

    Article  ADS  Google Scholar 

  13. Weaver, A. J., Saenko, O. A., Clark, P. U. & Mitrovica, J. X. Meltwater pulse 1A from Antarctica as a trigger of the Bølling-Allerød warm interval. Science 299, 1709–1713 (2003)

    Article  ADS  CAS  PubMed  Google Scholar 

  14. Rutt, I. C., Hagdorn, M., Hulton, N. R. J. & Payne, A. J. The Glimmer community ice sheet model. J. Geophys. Res. 114, F02004 (2009)

    Article  ADS  Google Scholar 

  15. Peltier, W. R. Global glacial isostasy and the surface of the ice-age Earth: the ice-5G (VM2) model and GRACE. Annu. Rev. Earth Planet. Sci. 32, 111–149 (2004)

    Article  ADS  CAS  Google Scholar 

  16. Munyikwa, K., Feathers, J. K., Rittenour, T. M. & Shrimpton, H. K. Constraining the Late Wisconsinan retreat of the Laurentide ice sheet from western Canada using luminescence ages from postglacial aeolian dunes. Quat. Geochronol. 6, 407–422 (2011)

    Article  Google Scholar 

  17. Hanebuth, T., Stattegger, K. & Grootes, P. M. Rapid flooding of the Sunda shelf: a late-glacial sea-level record. Science 288, 1033–1035 (2000)

    Article  ADS  CAS  PubMed  Google Scholar 

  18. Stanford, J. D. et al. Sea-level probability for the last deglaciation: a statistical analysis of far-field records. Glob. Planet. Change 79, 193–203 (2011)

    Article  ADS  Google Scholar 

  19. Bard, E., Hamelin, B. & Fairbanks, R. G. U-Th ages obtained by mass spectrometry in corals from Barbados: sea level during the past 130,000 years. Nature 346, 456–458 (1990)

    Article  ADS  CAS  Google Scholar 

  20. Fulton, R. J., Ryder, J. M. & Tsang, S. The Quaternary glacial record of British Columbia, Canada. Dev. Quat. Sci. 2, 39–50 (2004)

    Google Scholar 

  21. Davies, M. H. et al. The deglacial transition on the southeastern Alaska margin: meltwater input, sea level rise, marine productivity, and sedimentary anoxia. Paleoceanography 26, 18 (2011)

    Article  Google Scholar 

  22. Tarasov, L. & Peltier, W. R. A calibrated deglacial drainage chronology for the North American continent: evidence of an Arctic trigger for the Younger Dryas. Quat. Sci. Rev. 25, 659–688 (2006)

    Article  ADS  Google Scholar 

  23. Teller, J. T., Leverington, D. W. & Mann, J. D. Freshwater outbursts to the oceans from glacial Lake Agassiz and their role in climate change during the last deglaciation. Quat. Sci. Rev. 21, 879–887 (2002)

    Article  ADS  Google Scholar 

  24. Murton, J. B., Bateman, M. D., Dallimore, S. R., Teller, J. T. & Yang, Z. Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean. Nature 464, 740–743 (2010)

    Article  ADS  CAS  PubMed  Google Scholar 

  25. Weertman, J. Stability of ice-age ice sheets. J. Geophys. Res. 66, 3783–3792 (1961)

    Article  ADS  Google Scholar 

  26. Li, Y.-X., Törnqvist, T. E., Nevitt, J. M. & Kohl, B. Synchronizing a sea-level jump, final Lake Agassiz drainage, and abrupt cooling 8200 years ago. Earth Planet. Sci. Lett. 315–316, 41–50 (2012)

    Article  ADS  Google Scholar 

  27. Rohling, E. J. & Palike, H. Centennial-scale climate cooling with a sudden cold event around 8,200 years ago. Nature 434, 975–979 (2005)

    Article  ADS  CAS  PubMed  Google Scholar 

  28. Payne, A. & Sugden, D. Topography and ice sheet growth. Earth Surf. Process. Landf. 15, 625–639 (1990)

    Article  ADS  Google Scholar 

  29. Smith, R. S., Gregory, J. M. & Osprey, A. A description of the FAMOUS (version XDBUA) climate model and control run. Geosci. Model Dev. 1, 53–68 (2008)

    Article  ADS  Google Scholar 

  30. Gregoire, L. Modelling the Northern Hemisphere Climate and Ice Sheets During the Last Deglaciation. PhD thesis, Univ. Bristol. (2010)

  31. Marshall, S. J., James, T. S. & Clarke, G. K. C. North American ice sheet reconstructions at the Last Glacial Maximum. Quat. Sci. Rev. 21, 175–192 (2002)

    Article  ADS  Google Scholar 

  32. Charbit, S., Ritz, C., Philippon, G., Peyaud, V. & Kageyama, M. Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle. Clim. Past 3, 15–37 (2007)

    Article  Google Scholar 

  33. Zweck, C. & Huybrechts, P. Modeling of the Northern Hemisphere ice sheets during the last glacial cycle and glaciological sensitivity. J. Geophys. Res. 110, 103–127 (2005)

    Article  Google Scholar 

  34. Ganopolski, A., Calov, R. & Claussen, M. Simulation of the last glacial cycle with a coupled climate ice-sheet model of intermediate complexity. Clim. Past 6, 229–244 (2010)

    Article  Google Scholar 

  35. North Greenland Ice Core Project High-resolution record of Northern Hemisphere climate extending into the last interglacial period. Nature 431, 147–151 (2004)

    Article  Google Scholar 

  36. Amante, C. & Eakins, B. W. ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and Analysis (NOAA Technical Memorandum NESDIS NGDC-24, 2009); available at

  37. Laske, G. & Masters, G. A global digital map of sediment thickness. Eos 78, F483 (1997)

    Google Scholar 

  38. Le Meur, E. & Huybrechts, P. A comparison of different ways of dealing with isostasy: examples from modelling the Antarctic ice sheet during the last glacial cycle. Ann. Glaciol. 23, 309–317 (1996)

    Article  ADS  Google Scholar 

  39. Reeh, N. Parameterization of melt rate and surface temperature in the Greenland ice sheet. Polarforschung 59, 113–128 (1991)

    Google Scholar 

  40. Abe-Ouchi, A., Segawa, T. & Saito, F. Climatic conditions for modelling the Northern Hemisphere ice sheets throughout the ice age cycle. Clim. Past 3, 423–438 (2007)

    Article  Google Scholar 

  41. Spahni, R. et al. Atmospheric methane and nitrous oxide of the Late Pleistocene from Antarctic ice cores. Science 310, 1317–1321 (2005)

    Article  ADS  CAS  PubMed  Google Scholar 

  42. Berger, A. & Loutre, M. F. Astronomical solutions for paleoclimate studies over the last 3 million years. Earth Planet. Sci. Lett. 111, 369–382 (1992)

    Article  ADS  Google Scholar 

  43. Peltier, W. R. & Fairbanks, R. G. Global glacial ice volume and Last Glacial Maximum duration from an extended Barbados sea level record. Quat. Sci. Rev. 25, 3322–3337 (2006)

    Article  ADS  Google Scholar 

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This work was supported by the Marie Curie Research Training Network NICE (MRTN-CT-2006-036127) and the NERC QUEST (NE/D001846/1) and ORMEN (NE/C509558/1) projects. Glimmer was developed within the NERC National Centre for Earth Observation. We thank R. Kahana for providing part of the input climate data and for comments on the manuscript. We also thank members of the BRIDGE group, the NICE network and PALSEA, a PAGES/INQUA/WUN network, for discussions and suggestions. The numerical simulations were carried out using the computational facilities of the BRIDGE group and those of the Advanced Computing Research Centre, University of Bristol (

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Authors and Affiliations



L.J.G. performed the experiments, the analysis and wrote the manuscript. P.J.V. provided the input climate. All authors contributed to designing the experiments, discussed the results and implications and commented on the manuscript at all stages.

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Correspondence to Lauren J. Gregoire.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Table 1, Supplementary Figures 1-5, Supplementary References and a Supplementary Discussion, which provides a comparison of the modelled North American deglaciation with data and describes additional experiments referred to in the main text. (PDF 820 kb)

Supplementary Movie 1

This movie shows the evolution of ice elevation, surface mass balance and meltwater flux of the North American ice sheet through the last deglaciation. The two meltwater pulses happen when ice domes separate. The pulses are associated with an extension of the ablation area (area where melting is higher than snow accumulation) in the saddle between multiple ice domes. (MOV 5679 kb)

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Gregoire, L., Payne, A. & Valdes, P. Deglacial rapid sea level rises caused by ice-sheet saddle collapses. Nature 487, 219–222 (2012).

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