Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Antarctic ice dynamics amplified by Northern Hemisphere sea-level forcing

Abstract

Sea-level rise due to ice loss in the Northern Hemisphere in response to insolation and greenhouse gas forcing is thought to have caused grounding-line retreat of marine-based sectors of the Antarctic Ice Sheet (AIS)1,2,3. Such interhemispheric sea-level forcing may explain the synchronous evolution of global ice sheets over ice-age cycles. Recent studies that indicate that the AIS experienced substantial millennial-scale variability during and after the last deglaciation4,5,6,7 (roughly 20,000 to 9,000 years ago) provide further evidence of this sea-level forcing. However, global sea-level change as a result of mass loss from ice sheets is strongly nonuniform, owing to gravitational, deformational and Earth rotational effects8, suggesting that the response of AIS grounding lines to Northern Hemisphere sea-level forcing is more complicated than previously modelled1,2,6. Here, using an ice-sheet model coupled to a global sea-level model, we show that AIS dynamics are amplified by Northern Hemisphere sea-level forcing. As a result of this interhemispheric interaction, a large or rapid Northern Hemisphere sea-level forcing enhances grounding-line advance and associated mass gain of the AIS during glaciation, and grounding-line retreat and mass loss during deglaciation. Relative to models without these interactions, the inclusion of Northern Hemisphere sea-level forcing in our model increases the volume of the AIS during the Last Glacial Maximum (about 26,000 to 20,000 years ago), triggers an earlier retreat of the grounding line and leads to millennial-scale variability throughout the last deglaciation. These findings are consistent with geologic reconstructions of the extent of the AIS during the Last Glacial Maximum and subsequent ice-sheet retreat, and with relative sea-level change in Antarctica3,4,5,6,7,9,10.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Contributions to deglacial sea-level changes in Antarctica.
Fig. 2: Timing of Northern Hemisphere sea-level forcing and its influence on Antarctic ice volume changes.
Fig. 3: Enhanced Antarctic ice loss during MWP-1A and the early Holocene.
Fig. 4: Agreement of predicted sea-level and ice-cover changes with geological records in the Ross Sea sector.

Data availability

The datasets generated for this publication are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.919498) and as source data for Extended Data Fig. 9. The modelling results are available in the OSF database (https://osf.io/g5ur2/?view_only=8acbf1e38c184d9c8f09811c8bbef036). Source data are provided with this paper.

Code availability

The coupled ice-sheet–sea-level model used is reported in refs. 26,28; the PSU 3D ice-sheet model is reported in ref. 37. Ice-sheet and sea-level models are available on request from the authors of the references listed.

References

  1. 1.

    Denton, G. H. & Hughes, T. J. Milankovitch theory of ice ages: hypothesis of ice-sheet linkage between regional insolation and global climate. Quat. Res. 20, 125–144 (1983).

    Google Scholar 

  2. 2.

    Huybrechts, P. J. Sea-level changes at the LGM from ice-dynamic reconstructions of the Greenland and Antarctic ice sheets during the glacial cycles. Quat. Sci. Rev. 21, 203–231 (2002).

    ADS  Google Scholar 

  3. 3.

    Weber, M. E. et al. Interhemispheric ice-sheet synchronicity during the Last Glacial Maximum. Science 334, 1265–1269 (2011).

    ADS  CAS  PubMed  Google Scholar 

  4. 4.

    Weber, M. E. et al. Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation. Nature 510, 134–138 (2014).

    ADS  CAS  PubMed  Google Scholar 

  5. 5.

    Golledge, N. R. et al. Antarctic contribution to meltwater pulse 1A from reduced Southern Ocean overturning. Nat. Commun. 5, 5107 (2014).

    ADS  CAS  PubMed  Google Scholar 

  6. 6.

    Fogwill, C. J. et al. Antarctic ice sheet discharge driven by atmosphere–ocean feedbacks at the Last Glacial Termination. Sci. Rep. 7, 39979 (2017).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  7. 7.

    Bart, P. J., DeCesare, M., Rosenheim, B. E., Majewski, W. & McGlannan, A. A centuries-long delay between a paleo-ice-shelf collapse and grounding-line retreat in the Whales Deep Basin, eastern Ross Sea, Antarctica. Sci. Rep. 8, 12392 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  8. 8.

    Milne, G. A. & Mitrovica, J. X. Searching for eustasy in deglacial sea-level histories. Quat. Sci. Rev. 27, 2292–2302 (2008).

    ADS  Google Scholar 

  9. 9.

    Hall, B. L. & Denton, G. H. New relative sea-level curves for the southern Scott Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea. J. Quat. Sci. 14, 641–650 (1999).

    Google Scholar 

  10. 10.

    Fogwill, C. J. et al. Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal. Nat. Geosci. 13, 489–497 (2020).

    ADS  CAS  Google Scholar 

  11. 11.

    Kawamura, K. et al. Northern Hemisphere forcing of climatic cycles in Antarctica over the past 360,000 years. Nature 448, 912–916 (2007).

    ADS  CAS  PubMed  Google Scholar 

  12. 12.

    Huybers, P. & Denton, G. Antarctic temperature at orbital timescales controlled by local summer duration. Nat. Geosci. 1, 787–792 (2008).

    ADS  CAS  Google Scholar 

  13. 13.

    Clark, P. U. et al. The last glacial maximum. Science 325, 710–714 (2009).

    ADS  CAS  PubMed  Google Scholar 

  14. 14.

    Pollard, D., Chang, W., Haran, M., Applegate, P. & DeConto, R. Large ensemble modeling of the last deglacial retreat of the West Antarctic Ice Sheet: comparison of simple and advanced statistical techniques. Geosci. Model Dev. 9, 1697–1723 (2016).

    ADS  Google Scholar 

  15. 15.

    Clark, P. U. et al. Oceanic forcing of penultimate deglacial and last interglacial sea-level rise. Nature 577, 660–664 (2020).

    ADS  CAS  PubMed  Google Scholar 

  16. 16.

    Weertman, J. Stability of the junction of an ice sheet and an ice shelf. J. Glaciol. 13, 3–11 (1974).

    ADS  Google Scholar 

  17. 17.

    Schoof, C. Ice sheet grounding line dynamics: steady states, stability, and hysteresis. J. Geophys. Res. 112, F03S28 (2007).

    ADS  Google Scholar 

  18. 18.

    Denton, G. H., Hughes, T. J. & Karlén, W. Global ice-sheet system interlocked by sea level. Quat. Res. 26, 3–26 (1986).

    CAS  Google Scholar 

  19. 19.

    Tigchelaar, M., Timmermann, A., Friedrich, T., Heinemann, M. & Pollard, D. Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing. Cryosphere 13, 2615–2631 (2019).

    ADS  Google Scholar 

  20. 20.

    Yokoyama, Y., Lambeck, K., De Deckker, P., Johnston, P. & Fifield, L. K. Timing of the Last Glacial Maximum from observed sea-level minima. Nature 406, 713–716 (2000); corrigendum 412, 99 (2001).

    ADS  CAS  PubMed  Google Scholar 

  21. 21.

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

    ADS  CAS  PubMed  Google Scholar 

  22. 22.

    Bard, E., Hamelin, B. & Delanghe-Sabatier, D. Deglacial meltwater pulse 1B and Younger Dryas sea levels revisited with boreholes at Tahiti. Science 327, 1235–1237 (2010).

    ADS  CAS  PubMed  Google Scholar 

  23. 23.

    Abdul, N. A., Mortlock, R. A., Wright, J. D. & Fairbanks, R. G. Younger Dryas sea level and meltwater pulse 1B recorded in Barbados reef crest coral Acropora palmata. Paleoceanography 31, 330–344 (2016).

    ADS  Google Scholar 

  24. 24.

    Bakker, P., Clark, P. U., Golledge, N. R., Schmittner, A. & Weber, M. E. Centennial-scale Holocene climate variations amplified by Antarctic Ice Sheet discharge. Nature 541, 72–76 (2017).

    ADS  CAS  PubMed  Google Scholar 

  25. 25.

    Hallmann, N. et al. Ice volume and climate changes from a 6000 year sea-level record in French Polynesia. Nat. Commun. 9, 285 (2018).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  26. 26.

    Gomez, N., Pollard, D. & Mitrovica, J. X. A 3-D coupled ice sheet – sea level model applied to Antarctica through the last 40 ky. Earth Planet. Sci. Lett. 384, 88–99 (2013).

    ADS  CAS  Google Scholar 

  27. 27.

    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).

    ADS  CAS  Google Scholar 

  28. 28.

    Pollard, D., Gomez, N. & DeConto, R. M. Variations of the Antarctic Ice Sheet in a coupled ice sheet-Earth-sea level model: sensitivity to viscoelastic Earth properties. J. Geophys. Res. Earth Surf. 122, 2124–2138 (2017).

    ADS  Google Scholar 

  29. 29.

    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).

    ADS  Google Scholar 

  30. 30.

    Lambeck, K., Rouby, H., Purcell, A., Sun, Y. & Sambridge, M. Sea level and global ice volumes from the Last Glacial Maximum to the Holocene. Proc. Natl Acad. Sci. USA 111, 15296–15303 (2014).

    ADS  CAS  PubMed  Google Scholar 

  31. 31.

    Peltier, W. R., Argus, D. F. & Drummond, R. Space geodesy constrains ice age terminal deglaciation: the global ICE-6G_C (VM5a) model. J. Geophys. Res. Solid Earth 120, 450–487 (2015).

    ADS  Google Scholar 

  32. 32.

    Fretwell, P. et al. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375–393 (2013).

    ADS  Google Scholar 

  33. 33.

    Bard, E., Hamelin, B., Deschamps, P. & Camoin, G. Comment on “Younger Dryas sea level and meltwater pulse 1B recorded in Barbados reefal crest coral Acropora palmata” by N. A. Abdul et al. Paleoceanography 31, 1603–1608 (2016).

    ADS  Google Scholar 

  34. 34.

    Briggs, R. D. & Tarasov, L. How to evaluate model-derived deglaciation chronologies: a case study using Antarctica. Quat. Sci. Rev. 63, 109–127 (2013).

    ADS  Google Scholar 

  35. 35.

    Jones, R., Whitehouse, P., Bentley, M., Small, D. & Dalton, A. Impact of glacial isostatic adjustment on cosmogenic surface-exposure dating. Quat. Sci. Rev. 212, 206–212 (2019).

    ADS  Google Scholar 

  36. 36.

    Gomez, N., Pollard, D. & Holland, D. Sea-level feedback lowers projections of future Antarctic Ice Sheet mass loss. Nat. Commun. 6, 8798 (2015).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  37. 37.

    Pollard, D. & DeConto, R. M. Description of a hybrid ice sheet-shelf model, and application to Antarctica. Geosci. Model Dev. 5, 1273–1295 (2012).

    ADS  Google Scholar 

  38. 38.

    Kendall, R. A., Mitrovica, J. X. & Milne, G. A. On post-glacial sea level – II. Numerical formulation and comparative results on spherically symmetric models. Geophys. J. Int. 161, 679–706 (2005).

    ADS  Google Scholar 

  39. 39.

    Gomez, N., Mitrovica, J. X., Tamisiea, M. E. & Clark, P. U. A new projection of sea level change in response to collapse of marine sectors of the Antarctic Ice Sheet. Geophys. J. Int. 180, 623–634 (2010).

    ADS  Google Scholar 

  40. 40.

    MacAyeal, D. R. Large-scale ice flow over a viscous basal sediment: theory and application to ice stream B, Antarctica. J. Geophys. Res. Solid Earth 94, 4071–4087 (1989).

    Google Scholar 

  41. 41.

    Andrews, J. T. & Mahaffy, M. A. W. Growth rate of the Laurentide Ice Sheet and sea level lowering (with emphasis on the 115 000 BP sea level low). Quat. Res., 6, 167–183 (1976).

    Google Scholar 

  42. 42.

    Pattyn, F. et al. Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison. J. Glaciol. 59, 410–422 (2013).

    ADS  Google Scholar 

  43. 43.

    Pollard, D. & DeConto, R. M. A simple inverse method for the distribution of basal sliding coefficients under ice sheets, applied to Antarctica. Cryosphere 6, 953–971 (2012).

    ADS  Google Scholar 

  44. 44.

    Pattyn, F. Sea-level response to melting of Antarctic ice shelves on multi-centennial time scales with the fast elementary thermomechanical ice sheet model (f.ETISh v1.0). Cryosphere 11, 1851–1878 (2017).

    ADS  Google Scholar 

  45. 45.

    Tsai, V. C., Stewart, A. L. & Thompson, A. F. Marine ice-sheet profiles and stability under Coulomb basal conditions. J. Glaciol. 61, 205–215 (2015).

    ADS  Google Scholar 

  46. 46.

    Le Brocq, A. M., Payne, A. J. & Vieli, A. An improved Antarctic dataset for high resolution numerical ice sheet models (ALBMAP v1). Earth Syst. Sci. Data 2, 247–260 (2010).

    ADS  Google Scholar 

  47. 47.

    Lisiecki, L. E. & Raymo, M. E. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003 (2005); correction 20, PA2007 (2005).

    ADS  Google Scholar 

  48. 48.

    Liu, Z. et al. Transient simulation of last deglaciation with a new mechanism for Bolling-Allerod warming. Science 325, 310–314 (2009).

    ADS  CAS  PubMed  Google Scholar 

  49. 49.

    Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Phys. Earth Planet. Inter. 25, 297–356 (1981).

    ADS  Google Scholar 

  50. 50.

    Mitrovica, J. X. & Forte, A. M. A new inference of mantle viscosity based upon joint inversion of convection and glacial isostatic adjustment data. Earth Planet. Sci. Lett. 225, 177–189 (2004).

    ADS  CAS  Google Scholar 

  51. 51.

    Huybrechts, P. & de Wolde, J. The dynamic response of the Greenland and Antarctic ice sheets to multiple-century climatic warming. J. Clim. 12, 2169–2188 (1999).

    ADS  Google Scholar 

  52. 52.

    National Geophysical Data Center. 2-minute Gridded Global Relief Data (ETOPO2) v2 (NOAA, 2006); https://data.nodc.noaa.gov/cgi-bin/iso?id=gov.noaa.ngdc.mgg.dem:301.

  53. 53.

    Weber, M. E. et al. Dust transport from Patagonia to Antarctica – a new stratigraphic approach from the Scotia Sea and its implications for the last glacial cycle. Quat. Sci. Rev. 36, 177–188 (2012).

    ADS  Google Scholar 

  54. 54.

    Ruth, U. et al. “EDML1”: a chronology for the EPICA deep ice core from Dronning Maud Land, Antarctica, over the last 150 000 years. Clim. Past 3, 475–484 (2007).

    Google Scholar 

  55. 55.

    Veres, D. et al. The Antarctic ice core chronology (AICC2012): an optimized multi-parameter and multi-site dating approach for the last 120 thousand years. Clim. Past 9, 1733–1748 (2013).

    Google Scholar 

  56. 56.

    Bazin, L. et al. An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120–800 ka. Clim. Past 9, 1715–1731 (2013).

    Google Scholar 

  57. 57.

    Lamy, F. et al. Increased dust deposition in the Pacific Southern Ocean during glacial periods. Science 343, 403–407 (2014).

    ADS  CAS  PubMed  Google Scholar 

  58. 58.

    Martínez-García, A. et al. Iron fertilization of the subantarctic ocean during the last ice age. Science 343, 1347–1350 (2014).

    ADS  PubMed  Google Scholar 

  59. 59.

    Small, D., Bentley, M. J., Jones, R. S., Pittard, M. L. & Whitehouse, P. L. Antarctic ice sheet palaeo-thinning rates from vertical transects of cosmogenic exposure ages. Quat. Sci. Rev. 206, 65–80 (2019).

    ADS  Google Scholar 

Download references

Acknowledgements

N.G. and H.K.H. were supported by the Natural Sciences and Engineering Research Council (NSERC), the Canada Research Chair’s programme and the Canadian Foundation for Innovation, M.E.W. by the Deutsche Forschungsgemeinschaft (DFG; grant numbers We2039/8-1 and We 2039/17-1), and J.X.M. by NASA grant NNX17AE17G and Harvard University. We thank G. Tseng for assistance with exploratory research that informed this study, and D. Pollard for insight on and use of the PSU ice-sheet model.

Author information

Affiliations

Authors

Contributions

N.G. contributed the numerical modelling and analysis; H.K.H. prepared model input; M.E.W. contributed iceberg-rafted debris records and, together with P.U.C. and J.X.M., other published data and related discussion. All authors contributed to developing the idea and to writing and refining the manuscript.

Corresponding author

Correspondence to Natalya Gomez.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Frank Pattyn and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Sensitivity of results to ice and Earth model parameters.

a, Changes in Antarctic ice volume predicted in simulations with evolving (solid lines) and fixed (dashed lines) Northern Hemisphere ice mass, and adopting the LVZ Earth model (Methods). Blue lines are identical to those in Fig. 2b, corresponding to a basal sliding coefficient of b = 10−5 m yr−1 Pa−2; red lines correspond to a basal sliding coefficient of b = 10−6 m yr−1 Pa−2. The black dotted line shows changes in Northern Hemisphere ice volume (right axis; in metres of global-mean sea level (gmsl) equivalent) prescribed in the ICE5G27 ice history. b, As in a, but adopting the HV Earth model (Methods). Blue (a) and red (b) vertical bands represent the timing of MWP and AID events, as in Fig. 2a, c, respectively.

Extended Data Fig. 2 Evolution of Antarctic ice cover with and without Northern Hemisphere sea-level forcing.

a, b, Thickness of grounded ice (in metres) and extent of ice shelves, at 30 ka, 20 ka, 10 ka and the present day, predicted from simulations that include variations in the Northern Hemisphere ice sheets represented by the ICE5G27 ice history (a) and from simulations in which ice cover in the Northern Hemisphere remains fixed (b). Black lines show the grounding lines. c, The difference in grounded ice thickness between simulations in a and b, representing the effect of sea-level changes associated with Northern Hemisphere ice sheets on the evolution of the AIS. Green and black lines represent the positions of the grounding lines with (a) and without (b) the Northern Hemisphere sea-level forcing included.

Extended Data Fig. 3 Influence of Northern Hemisphere sea-level forcing on Antarctic ice cover during the deglaciation.

The colour scale indicates the difference in the thickness (in metres) of grounded ice, at the indicated times, between simulations that include variations in the Northern Hemisphere ice sheets from ICE5G27 ice history and in which ice cover in the Northern Hemisphere remains fixed throughout the simulation. Differences are displayed as in Fig. 3c, but every 1 kyr for the past 19 kyr. Green and black lines represent the positions of the grounding lines with and without the Northern Hemisphere sea-level forcing included, respectively.

Extended Data Fig. 4 Antarctic ice-volume changes in the Ross Sea and Weddell Sea sectors.

a, Changes in ice volume in the Weddell Sea sector predicted in simulations with fixed (red) and evolving (black) Northern Hemisphere ice from the ICE5G27 ice history. b, As in a, but for the Ross Sea sector. c, Blue lines outline the areas included in the calculations in a and b; colour scale indicates the change in ice thickness (in metres) from 20 ka to the present day in the simulations that include Northern Hemisphere ice-cover changes from ICE5G27.

Extended Data Fig. 5 Influence of Northern Hemisphere sea-level forcing on the rate of Antarctic ice loss.

ae, Rate of change of Antarctic ice volume, including grounded and floating ice, calculated with a 100-year running mean, predicted from simulations including (black) and excluding (red) Northern Hemisphere ice-cover changes, using the ice histories indicated in the legend (Methods). The mean and standard deviation of these five panels are shown in Fig. 3a.

Extended Data Fig. 6 Patterns of sea-level change for Antarctic ice loss during MWP-1A and the early Holocene.

a, b, Predicted sea-level change, normalized by the global-mean sea-level-equivalent associated with Antarctic ice loss during MWP-1A (a) and the early Holocene (including MWP-1B; b). Calculations are associated with simulations that include Northern Hemisphere ice cover changes given by ICE5G27. The patterns of sea-level change and the global mean sea-level equivalent used in the normalization are calculated over the time windows indicated by the green vertical bands in Fig. 2b. Green and magenta asterisks indicate the locations of the far-field relative sea-level records in Tahiti and Barbados.

Extended Data Fig. 7 Sensitivity of the Weddell Sea sector to geographic variability in sea-level forcing.

a, Same as Fig. 3b, but zoomed in on the Weddell Sea region, where geographically variable sea-level changes associated with Northern Hemisphere ice loss are largest (Fig. 1c). The colour scale shows the change in ice thickness predicted from a simulation adopting the ICE5G27 ice history in the Northern Hemisphere, which includes geographically variable sea-level changes associated with gravitational, deformational and Earth rotational effects activated by ice-cover changes globally, during MWP-1A (14.5–13.5 ka). Grey and black lines indicate the grounding-line position at the start and end of the time interval, respectively. b, The difference between a and the same calculation but adopting the simulation with globally uniform sea-level change from the Northern Hemisphere. The black line is as in a; the blue line indicates the grounding-line position at the end of the time interval for the uniform sea-level simulation. c, Antarctic ice-volume variations from simulations with geographically variable (black) and uniform (red) sea-level changes associated with Northern Hemisphere ice loss over the MWP-1A interval. df, As in ac, but for the early Holocene interval (11.5–9 ka). In this case, d is the same as Fig. 3d, but zoomed in on the Weddell Sea region. The uniform sea-level change is calculated relative to modern topography and scaled such that the total contribution to global sea-level change from the Northern Hemisphere over the last deglaciation (since 21 ka) is 95.5 m, in agreement with ref. 27.

Extended Data Fig. 8 Predicted Antarctic ice-volume changes and global-mean sea-level contributions.

a, Changes in AIS volume predicted in a simulation with Northern Hemisphere ice cover fixed at the 40 ka configuration within ICE5G27 (solid red line) and in simulations with evolving Northern Hemisphere ice adopting the ICE5G27 (solid black line), ICE6GC31 (dashed black line) and ANU30 (cyan line) ice histories, as well as two composite ice histories in which ice cover over North America and Greenland in ICE5G has been replaced by regional GLAC1D29 models (blue lines). The dashed red line represents a simulation in which the Northern Hemisphere ice sheets are fixed at the modern configuration rather than at the 40 ka configuration throughout the simulation. In this case, marine-based sectors of the AIS start on even shallower bedrock, and hence the predicted ice-sheet growth is larger at the LGM, while the ice loss during the deglaciation occurs later and is of even smaller magnitude than in the original simulation. Note that this is not a realistic starting configuration. b, As in a, but expressed as a global-mean sea-level-equivalent (GMSLE) relative to the modern state. This is calculated by taking the ice above floatation thickness in Antarctica relative to the palaeo bedrock topography at each time step in the model, and dividing by the area of the modern ocean. Note that a and b are not directly proportional because as the bedrock topography in Antarctica evolves the volume of ice above floatation in marine sectors also changes. Blue (a) and red (b) vertical bands represent the timing of MWP and AID events, as in Fig. 2a, c, respectively.

Extended Data Fig. 9 Age model comparison and uncertainty for IBRD flux record from Iceberg Alley.

a, Age difference between the AICC 201255,56 and EDML154 age models. b, Age uncertainty in the AICC 2012 age model. c, IBRD flux time series adopting the AICC 2012 (black line, as in Figs. 2c, 4b) and EDML1/EDC3 (blue dotted line) age scales. The IBRD stack is composed of records from sites MD07-3133 and MD07-3134. It is presented here for 20–0 ka and was combined with previous data for 27–7 ka4 and 8–0 ka24. Vertical brown bars indicate AID events 1–74 on the AICC 2012 age scale. Blue vertical bars indicate MWP-1A21 and MWP-1B22. Horizontal black error bars show propagated uncertainties for the upper and lower bounds of each AID event for errors in tie-point correlation to EDML4 and uncertainties of the AICC 2012 age model.

Source data.

Extended Data Fig. 10 Comparison of predicted and observed ice-thickness changes in the Weddell Sea region.

a, b, Predicted (lines) and observed (error bars) ice thickness (in metres) above the modern thickness at sites 11–13 (a) and 14, 15 (b) from ref. 35. Predictions are from simulations in which Northern Hemisphere ice cover is evolving according to ICE5G27 (black lines) or is fixed (blue lines). Error bars show cosmogenic exposure age data with 2σ uncertainty from ref. 35. c, Map of predicted ice thickness at 12 ka, in the simulation with ICE5G27. The locations of the relevant sites in the Weddell Sea and Ross Sea (see Extended Data Fig. 11) regions are indicated. See Methods for further discussion of these results.

Extended Data Fig. 11 Comparison of predicted and observed ice-thickness changes in the Ross Sea region.

a, Predicted (lines) and observed (2σ error bars) ice thickness (in metres) above the modern thickness at Scott Coast site S (black) and sites 1 (red) and 3–5 (shades of blue) from ref. 35. The locations of the sites are indicated in be. Predictions are from simulations in which Northern Hemisphere ice cover is evolving according to ICE5G27 (solid lines) or is fixed (dashed lines). Observations are cosmogenic exposure age data from ref. 35. Red vertical bands represent the timing of AID events 1 and 2, as in Fig. 2c. b, Map of predicted ice thickness 12 ka in the Ross Sea, in the simulation with evolving Northern Hemisphere ice. ce, The difference in ice thickness between 12 ka (b) and 11 ka (c), 10 ka (d) and 9 ka (e). See Methods for further discussion of these results.

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Gomez, N., Weber, M.E., Clark, P.U. et al. Antarctic ice dynamics amplified by Northern Hemisphere sea-level forcing. Nature 587, 600–604 (2020). https://doi.org/10.1038/s41586-020-2916-2

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links