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.

The Paris Climate Agreement and future sea-level rise from Antarctica

Nature volume 593, pages 83–89 (2021)Cite this article

Subjects

Abstract

The Paris Agreement aims to limit global mean warming in the twenty-first century to less than 2 degrees Celsius above preindustrial levels, and to promote further efforts to limit warming to 1.5 degrees Celsius1. The amount of greenhouse gas emissions in coming decades will be consequential for global mean sea level (GMSL) on century and longer timescales through a combination of ocean thermal expansion and loss of land ice2. The Antarctic Ice Sheet (AIS) is Earth’s largest land ice reservoir (equivalent to 57.9 metres of GMSL)3, and its ice loss is accelerating4. Extensive regions of the AIS are grounded below sea level and susceptible to dynamical instabilities5,6,7,8 that are capable of producing very rapid retreat8. Yet the potential for the implementation of the Paris Agreement temperature targets to slow or stop the onset of these instabilities has not been directly tested with physics-based models. Here we use an observationally calibrated ice sheet–shelf model to show that with global warming limited to 2 degrees Celsius or less, Antarctic ice loss will continue at a pace similar to today’s throughout the twenty-first century. However, scenarios more consistent with current policies (allowing 3 degrees Celsius of warming) give an abrupt jump in the pace of Antarctic ice loss after around 2060, contributing about 0.5 centimetres GMSL rise per year by 2100—an order of magnitude faster than today4. More fossil-fuel-intensive scenarios9 result in even greater acceleration. Ice-sheet retreat initiated by the thinning and loss of buttressing ice shelves continues for centuries, regardless of bedrock and sea-level feedback mechanisms10,11,12 or geoengineered carbon dioxide reduction. These results demonstrate the possibility that rapid and unstoppable sea-level rise from Antarctica will be triggered if Paris Agreement targets are exceeded.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Antarctic contribution to future GMSL rise.
Fig. 2: Ice-sheet evolution following the +3 °C global warming emissions trajectory.
Fig. 3: AIS thresholds and commitments to GMSL rise with delayed mitigation.

Data availability

Model-generated data associated with this work are available with this paper. Three-dimensional ice-sheet model output associated with Fig. 2 and Extended Data Figs. 3, 5 are available at the ScholarWorks@UMASS Amherst repository (https://doi.org/10.7275/j005-r778). Climate model forcing used in our main ensembles and meltwater-feedback simulations (Fig. 1) are reported in refs. 46,80. Source data are provided with this paper.

Code availability

The modified ice-sheet model codes based on ref. 51 are available from the corresponding author. CESM1.2.2 GCM87 is available from NCAR (https://www.cesm.ucar.edu/models/cesm1.2/) and the RCM is reported in ref. 79. The Earth–sea level model is described in refs. 12,49.

References

  1. UNFCCC. Adoption of the Paris Agreement FCCC/CP/2015/L.9/Rev.1 (United Nations Framework Convention on Climate Change, 2015); https://unfccc.int/resource/docs/2015/cop21/eng/l09r01.pdf.

  2. Mengel, M., Nauels, A., Rogelj, J. & Schleussner, C.-F. Committed sea-level rise under the Paris Agreement and the legacy of delayed mitigation action. Nat. Commun. 9, 601 (2018).

    Article  PubMed  PubMed Central  ADS  CAS  Google Scholar 

  3. Morlighem, M. et al. Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet. Nat. Geosci. 13, 132–137 (2020).

    Article  CAS  ADS  Google Scholar 

  4. Shepherd, A. et al. Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature 558, 219–222 (2018).

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  7. Pollard, D., DeConto, R. M. & Alley, R. B. Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure. Earth Planet. Sci. Lett. 412, 112–121 (2015).

    Article  CAS  ADS  Google Scholar 

  8. DeConto, R. M. & Pollard, D. Contribution of Antarctica to past and future sea-level rise. Nature 531, 591–597 (2016).

    Article  CAS  PubMed  ADS  Google Scholar 

  9. Meinshausen, N. et al. The RCP greenhouse gas concentrations and their extensions from 1765 to 2300. Clim. Change 109, 213–241 (2011).

    Article  CAS  ADS  Google Scholar 

  10. Barletta, V. R. et al. Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability. Science 360, 1335–1339 (2018).

    Article  CAS  PubMed  ADS  Google Scholar 

  11. Larour, E. et al. Slowdown in Antarctic mass loss from solid Earth and sea-level feedbacks. Science 364, eaav7908 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  13. Fürst, J. J. et al. The safety band of Antarctic ice shelves. Nat. Clim. Chang. 6, 479 (2016).

    Article  ADS  Google Scholar 

  14. Paolo, F. S., Fricker, H. & Padman, L. Volume loss from Antarctic ice shelves is accelerating. Science 348, 327–331 (2015).

    Article  CAS  PubMed  ADS  Google Scholar 

  15. Gudmundsson, G. H. Ice-shelf buttressing and the stability of marine ice sheets. Cryosphere 7, 647–655 (2013).

    Article  ADS  Google Scholar 

  16. Bassis, J. N. & Walker, C. C. Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice. Proc. R. Soc. Lond. A 468, 913–931 (2012).

    ADS  Google Scholar 

  17. Parizek, B. R. et al. Ice-cliff failure via retrogressive slumping. Geology 47, 1–4 (2019).

    Article  Google Scholar 

  18. Clerc, F., Minchew, B. M. & Behn, M. D. Marine ice cliff instability mitigated by slow removal of ice shelves. Geophys. Res. Lett. 46, 12108–12116 (2019).

    Article  ADS  Google Scholar 

  19. Vaughan, D. G. Relating the occurrence of crevasses to surface strain rates. J. Glaciol. 39, 255–266 (1993).

    Article  ADS  Google Scholar 

  20. Schlemm, T. & Levermann, A. A simple stress-based cliff-calving law. Cryosphere 13, 2475–2488 (2019).

    Article  ADS  Google Scholar 

  21. An, L. et al. Bed elevation of Jakobshavn Isbræ, West Greenland, from high-resolution airborne gravity and other data. Geophys. Res. Lett. 44, 3728–3736 (2017).

    Article  ADS  Google Scholar 

  22. Khazendar, A. et al. Interruption of two decades of Jakobshavn Isbræ acceleration and thinning as regional ocean cools. Nat. Geosci. 12, 277–283 (2019).

    Article  CAS  ADS  Google Scholar 

  23. Joughin, I. et al. Seasonal to decadal scale variations in the surface velocity of Jakobshavn Isbræ, Greenland: observation and model-based analysis. J. Geophys. Res. Earth Surf. 117, F02030 (2012).

    Article  ADS  Google Scholar 

  24. Rignot, E. et al. Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf. Geophys. Res. Lett. 31, L18401 (2004).

    Article  ADS  CAS  Google Scholar 

  25. Scambos, T. A., Berthier, E. & Shuman, C. A. The triggering of subglacial lake drainage during rapid glacier drawdown: Crane Glacier, Antarctic Peninsula. Ann. Glaciol. 52, 74–82 (2011).

    Article  ADS  Google Scholar 

  26. Milillo, P. et al. Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica. Sci. Adv. 5, eaau3433 (2019).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  27. Atkinson, B. K. Subcritical crack growth in geological materials. J. Geophys. Res. Solid Earth 89, 4077–4114 (1984).

    Article  CAS  Google Scholar 

  28. Kuipers Munneke, P., Ligtenberg, S. R. M., van den Broeke, M. R. & Vaughan, D. G. Firn air depletion as a precursor of Antarctic ice-shelf collapse. J. Glaciol. 60, 205–214 (2014).

    Article  ADS  Google Scholar 

  29. Banwell, A. F., Willis, I. C., Macdonald, G. J., Goodsell, B. & MacAyeal, D. R. Direct measurements of ice-shelf flexure caused by surface meltwater ponding and drainage. Nat. Commun. 10, 730 (2019).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  30. Trusel, L. D. et al. Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios. Nat. Geosci. 8, 927–932 (2015).

    Article  CAS  ADS  Google Scholar 

  31. Robel, A. A. & Banwell, A. F. A speed limit on ice shelf collapse through hydrofracture. Geophys. Res. Lett. 46, 12092–12100 (2019).

    Article  ADS  Google Scholar 

  32. Fawcett, A. A. et al. Can Paris pledges avert severe climate change? Science 350, 1168–1169 (2015).

    Article  CAS  PubMed  ADS  Google Scholar 

  33. Edwards, T. L. et al. Revisiting Antarctic ice loss due to marine ice-cliff instability. Nature 566, 58–64 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

  34. Dutton, A., Webster, J. M., Zwartz, D. & Lambeck, K. Tropical tales of polar ice: evidence of Last Interglacial polar ice sheet retreat recorded by fossil reefs of the granitic Seychelles islands. Quat. Sci. Rev. 107, 182–196 (2015).

    Article  ADS  Google Scholar 

  35. Grant, G. R. et al. The amplitude and origin of sea-level variability during the Pliocene epoch. Nature 574, 237–241 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

  36. Dumitru, O. A. et al. Constraints on global mean sea level during Pliocene warmth. Nature 574, 233–236 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

  37. Gilford, D. M. et al. Could the Last Interglacial constrain projections of future Antarctic ice mass loss and sea-level rise? J. Geophys. Res. Earth Surf. 125, e2019JF005418 (2020).

    Article  ADS  Google Scholar 

  38. Velicogna, I., Sutterley, T. C. & van den Broeke, M. Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time‐variable gravity data. Geophys. Res. Lett. 41, 8130–8137 (2014).

    Article  ADS  Google Scholar 

  39. Rohling, E. J. et al. Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand. Nat. Commun. 10, 5040 (2019).

    Article  PubMed  PubMed Central  ADS  CAS  Google Scholar 

  40. Cook, C. P. et al. Dynamic behaviour of the East Antarctic Ice Sheet during Pliocene warmth. Nat. Geosci. 6, 765–769 (2013).

    Article  CAS  ADS  Google Scholar 

  41. Golledge, N. R. et al. Global environmental consequences of twenty-first-century ice-sheet melt. Nature 566, 65–72 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

  42. Seroussi, H. & Morlighem, M. Representation of basal melting at the grounding line in ice flow models. Cryosphere 12, 3085–3096 (2018).

    Article  ADS  Google Scholar 

  43. Tsai, V. C., Stewart, A. L. & Thompson, A. F. Marine ice-sheet profiles and stability under coulomb basal conditions. J. Glaciol. 61, 205–215 (2017).

    Article  Google Scholar 

  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).

    Article  ADS  Google Scholar 

  45. Seroussi, H. et al. ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century. Cryosphere 14, 3033–3070 (2020).

    Article  ADS  Google Scholar 

  46. Sadai, S., Condron, A., DeConto, R. & Pollard, D. Future climate response to Antarctic Ice Sheet melt caused by anthropogenic warming. Sci. Adv. 6, eaaz1169 (2020).

    Article  PubMed  PubMed Central  ADS  Google Scholar 

  47. Bell, R. E. et al. Antarctic ice shelf potentially stabilized by export of meltwater in surface river. Nature 544, 344–348 (2017).

    Article  CAS  PubMed  ADS  Google Scholar 

  48. Lai, C.-Y. et al. Vulnerability of Antarctica’s ice shelves to meltwater-driven fracture. Nature 584, 574–578 (2020).

    Article  CAS  PubMed  ADS  Google Scholar 

  49. Pollard, D., Gomez, N. & DeConto, R. 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, 2169–9011 (2017).

    Article  Google Scholar 

  50. Powell, E., Gomez, N., Hay, C., Latychev, K. & Mitrovica, J. X. Viscous effects in the solid earth response to modern Antarctic ice mass flux: implications for geodetic studies of WAIS stability in a warming world. J. Clim. 33, 443–459 (2020).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  52. 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).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  54. Holland, P. R., Jenkins, A. & Holland, D. The response of ice shelf basal melting to variations in ocean temperature. J. Clim. 21, 2558–2572 (2008).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  56. Rignot, E., Jacobs, S., Mouginot, J. & Scheuchl, B. Ice shelf melting around Antarctica. Science 314, 266–270 (2013).

    Article  ADS  CAS  Google Scholar 

  57. Schmidtko, S., Heywood, K. J., Thompson, A. F. & Aoki, S. Multidecadal warming of Antarctic waters. Science 346, 1227–1231 (2014).

    Article  CAS  PubMed  ADS  Google Scholar 

  58. Nick, F. M., Van der Veen, C. J., Vieli, A. & Benn, D. I. A physically based calving model applied to marine outlet glaciers and implications for the glacier dynamics. J. Glaciol. 56, 781–794 (2010).

    Article  ADS  Google Scholar 

  59. Tsai, C.-Y., Forest, C. E. & Pollard, D. The role of internal climate variability in projecting Antarctica’s contribution to future sea-level rise. Clim. Dyn. 55, 1875–1892 (2020).

    Article  Google Scholar 

  60. Benn, D. I., Warren, C. R. & Mottram, R. H. Calving processes and the dynamics of calving glaciers. Earth Sci. Rev. 82, 143–179 (2007).

    Article  ADS  Google Scholar 

  61. Ma, Y., Tripathy, C. S. & Bassis, J. N. Bounds on the calving cliff height of marine terminating glaciers. Geophys. Res. Lett. 44, 1369–1375 (2017).

    Article  ADS  Google Scholar 

  62. Robel, A. A. Thinning sea ice weakens buttressing force of iceberg mélange and promotes calving. Nat. Commun. 8, 14596 (2017).

    Article  PubMed  PubMed Central  ADS  Google Scholar 

  63. Joughin, I., Shean, D. E., Smith, B. E. & Floricioiu, D. A decade of variability on Jakobshavn Isbræ: ocean temperatures pace speed through influence on mélange rigidity. Cryosphere 14, 211–227 (2020).

    Article  PubMed  PubMed Central  ADS  Google Scholar 

  64. Pollard, D., DeConto, R. M. & Alley, R. B. A continuum model (PSUMEL1) of ice mélange and its role during retreat of the Antarctic Ice Sheet. Geosci. Model Dev. 11, 5149–5172 (2018).

    Article  ADS  Google Scholar 

  65. Locarnini, R. A. et al. World Ocean Atlas 2013, Volume 1: Temperature (National Oceanographic Data Center, 2013).

  66. Bindschadler, R. A. et al. Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project). J. Glaciol. 59, 195–224 (2013).

    Article  ADS  Google Scholar 

  67. Le Brocq, A., 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).

    Article  ADS  Google Scholar 

  68. Jenkins, A. et al. West Antarctic Ice Sheet retreat in the Amundsen Sea driven by decadal oceanic variability. Nat. Geosci. 11, 733–738 (2018).

    Article  CAS  ADS  Google Scholar 

  69. Whitehouse, P. L., Bentley, M. J., Milne, G. A., King, M. A. & Thomas, I. D. A new glacial isostatic adjustment model for Antarctica: calibrated and tested using observations of relative sea-level change and present-day uplift rates. Geophys. J. Int. 190, 1464–1482 (2012).

    Article  ADS  Google Scholar 

  70. Ivins, E. R. et al. Antarctic contribution to sea level rise observed by GRACE with improved GIA correction. J. Geophys. Res. Solid Earth 118, 3126–3141 (2013).

    Article  ADS  Google Scholar 

  71. Geruo, A., Wahr, J. & Zhong, S. Computations of the viscoelastic response of a 3-D compressible Earth to surface loading: an application to Glacial Isostatic Adjustment in Antarctica and Canada. Geophys. J. Int. 192, 557–572 (2013).

    Article  ADS  Google Scholar 

  72. Capron, E. et al. Temporal and spatial structure of multi-millennial temperature changes at high latitudes during the last interglacial. Quat. Sci. Rev. 103, 116–133 (2014).

    Article  ADS  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

  74. Austermann, J., Mitrovica, J. X., Huybers, P. & Rovere, A. Detection of a dynamic topography signal in last interglacial sea-level records. Sci. Adv. 3, e1700457 (2017).

    Article  PubMed  PubMed Central  ADS  Google Scholar 

  75. Goelzer, H., Huybrechts, P., Loutre, M.-F. & Fichefet, T. Last Interglacial climate and sea-level evolution from a coupled ice sheet–climate model. Clim. Past 12, 2195–2213 (2016).

    Article  Google Scholar 

  76. Helsen, M. M., van de Berg, W. J., van de Wal, R. S. W., van den Broeke, M. R. & Oerlemans, J. Coupled regional climate-ice-sheet simulation shows limited Greenland ice loss during the Eemian. Clim. Past 9, 1773–1788 (2013).

    Article  Google Scholar 

  77. NEEM community members. Eemian interglacial reconstructed from a Greenland folded ice core. Nature 493, 489–494 (2013).

    Article  ADS  CAS  Google Scholar 

  78. Nicholl, J. A. L. et al. A Laurentide outburst flooding event during the last interglacial period. Nat. Geosci. 5, 901–904 (2012).

    Article  CAS  ADS  Google Scholar 

  79. Pal, J. S. et al. Regional climate modeling for the developing world – the ITCP RegCM3 and RegCNET. Bull. Am. Meteorol. Soc. 88, 1395–1409 (2007).

    Article  ADS  Google Scholar 

  80. Shields, C. A. & Kiehl, J. T. Simulating the Pineapple Express in the half degree Community Climate System Model, CCSM4. Geophys. Res. Lett. 43, 7767–7773 (2016).

    Article  ADS  Google Scholar 

  81. van Wessem, J. M. et al. Updated cloud physics in a regional atmospheric climate model improves the modelled surface energy balance of Antarctica. Cryosphere 8, 125–135 (2014).

    Article  ADS  Google Scholar 

  82. Lenaerts, J. T. M., Vizcaino, M., Fyke, J., van Kampenhout, L. & van den Broeke, M. R. Present‐day and future Antarctic ice sheet climate and surface mass balance in the Community Earth System Model. Clim. Dyn. 47, 1367–1381 (2016).

    Article  Google Scholar 

  83. Morelli, A. & Danesi, S. Seismological imaging of the Antarctic continental lithosphere: a review. Global Planet. Change 42, 155–165 (2004).

    Article  ADS  Google Scholar 

  84. Heeszel, D. S. et al. Upper mantle structure of central and West Antarctica from array analysis of Rayleigh wave phase velocities. J. Geophys. Res. Solid Earth 121, 1758–1775 (2016).

    Article  ADS  Google Scholar 

  85. Nield, G. A. et al. Rapid bedrock uplift in the Antarctic Peninsula explained by viscoelastic response to recent ice unloading. Earth Planet. Sci. Lett. 397, 32–41 (2014).

    Article  CAS  ADS  Google Scholar 

  86. Zhao, C. et al. Rapid ice unloading in the Fleming glacier region, southern Antarctic Peninsula, and its effect on bedrock uplift rates. Earth Planet. Sci. Lett. 473, 164–176 (2017).

    Article  CAS  ADS  Google Scholar 

  87. Hurrell, J. W. et al. The Community Earth System Model: a framework for collaborative research. Bull. Am. Meteorol. Soc. 94, 1339–1360 (2013).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank T. Naish for guidance on Pliocene sea-level targets. This research was supported by the NSF under awards 1664013, 2035080, 1443347 and 1559040, and by a grant to the NASA Sea Level Change Team 80NSSC17K0698.

Author information

Authors and Affiliations

  1. Department of Geosciences, University of Massachusetts Amherst, Amherst, MA, USA

    Robert M. DeConto, Shaina Sadai & Dawei Li

  2. Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA

    David Pollard & Richard B. Alley

  3. Department of Geosciences, Pennsylvania State University, University Park, PA, USA

    Richard B. Alley

  4. Earth System Science, University of California, Irvine, CA, USA

    Isabella Velicogna

  5. School of Geographical Sciences, University of Bristol, Bristol, UK

    Edward Gasson

  6. Department of Earth and Planetary Sciences, McGill University, Montreal, Quebec, Canada

    Natalya Gomez

  7. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA

    Alan Condron

  8. Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA

    Daniel M. Gilford, Erica L. Ashe & Robert E. Kopp

  9. School of Oceanography, Shanghai Jiao Tong University, Shanghai, China

    Dawei Li

  10. Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA

    Andrea Dutton

Authors
  1. Robert M. DeConto
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. David Pollard
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Richard B. Alley
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Isabella Velicogna
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Edward Gasson
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Natalya Gomez
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Shaina Sadai
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Alan Condron
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Daniel M. Gilford
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Erica L. Ashe
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Robert E. Kopp
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Dawei Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Andrea Dutton
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

R.M.D. and D.P. conceived the model experiments and developed the main model codes with conceptual input from R.B.A.; R.M.D. and D.P. wrote the manuscript with input from R.B.A., I.V., E.G., N.G., and S.S.; I.V. provided GRACE mass change estimates; E.G. contributed to climate forcing scenarios; S.S. and A.C. provided CESM1.2.2 climatologies; N.G. collaborated on coupled ice–Earth simulations; A.D. provided palaeo sea-level target ranges; D.L. compiled CMIP5 and CMIP6 GCM results; and D.M.G., E.L.A. and R.E.K. developed the statistical model described in Supplementary Information.

Corresponding author

Correspondence to Robert M. DeConto.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Jacqueline Austermann 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 Ensemble observational targets.

196 simulations (grey lines), each using a unique combination of hydrofracturing and ice-cliff calving parameters (Extended Data Table 1) compared with observations (blue dashed boxes). Solid blue lines show simulations without hydrofracturing and ice-cliff calving. Red lines show simulations with maximum parameter values in our main ensemble. Additional simulations (black lines) allow ice-cliff calving rates of up to 26 km yr−1, twice the maximum value used in our main ensembles. The vertical heights of the blue boxes represent the likely range of observations. Changes in ice mass above floatation are shown in equivalent GMSL. a, Simulated annual contributions to GMSL in the RCP8.5 ensemble compared with the 1992–2017 IMBIE4 observational average (0.15–0.46 mm yr−1; dashed blue box). b, LIG ensemble simulations from 130 to 125 kyr ago. The height of the dashed blue box shows the LIG target range (3.1–6.1 m), the width represents ~1,000-yr age uncertainty34. c, The same LIG simulations as in b, showing the rate of GMSL change contributed by Antarctica, smoothed over a 25-yr window. The peak in the early LIG is mainly caused by marine-based ice loss in West Antarctica. d, The same as b, except for warmer mid-Pliocene conditions. Maximum ice loss is compared with observational estimates of 11–21 m (refs. 35,36; blue dashed lines). Note the saturation of the simulated GMSL values near the top of the LIG and Pliocene ensemble range, and the failure of the model to produce realistic LIG or Pliocene sea levels without hydrofracturing and ice-cliff calving enabled (blue lines).

Source data

Extended Data Fig. 2 RCP8.5 ensembles calibrated with alternative GRACE estimates.

a, b, The fan charts show the time-evolving uncertainty and range around the median ensemble value (black line) in 10% increments. RCP8.5 ice-sheet model ensembles calibrated with GRACE estimates of annual mass change averaged from 2002–2017 using alternative GIA corrections (Methods). Use of GIA corrections produces estimates of mass loss between 2002 and 2017 of 0.2–0.54 mm yr−1 (a) and 0.39–0.53 mm yr−1 (b). The more restrictive and higher range of GRACE estimates in b skews the distribution and shifts the ensemble median values of GMSL upwards from 27 cm to 30 cm in 2100 and from 4.44 m to 4.94 m in 2200.

Extended Data Fig. 3 Last Interglacial and Pliocene ice-sheet simulations.

a–e, Ice-sheet simulations with the updated model physics used in our future ensembles and driven with the same LIG and Pliocene climate forcing used in ref. 8. Simulations without hydrofracturing and ice-cliff calving (a, b, d) correspond to blue lines in Extended Data Fig. 1. Simulations using maximum hydrofracturing and ice-cliff calving parameters (c, e) correspond to red lines in Extended Data Fig. 1. a, Modern (1950) ice-sheet simulation. b, c, LIG simulations run from 130 to 125 kyr ago are shown at 125 kyr ago. Values at the top of each panel are the maximum GMSL contribution between 129 and 128 kyr ago. Values in parentheses are the GMSL contribution at 125 kyr ago. d, e, Warm Pliocene simulations. Values shown are the maximum GMSL achieved during the simulations. Smaller values in parentheses show GMSL contributions after 5,000 model years (Extended Data Fig. 2d). Ice mass gain after peak retreat is caused by post-retreat bedrock rebound and enhanced precipitation in the warm Pliocene atmosphere.

Extended Data Fig. 4 RCP8.5 ensembles calibrated with modern and palaeo observations.

The fan charts show the time-evolving uncertainty and range around the median ensemble value (black line) in 10% increments. Mean and median ensemble values are shown at 2100. a, Raw ensemble with a range of plausible model parameters based on glaciological observations (Extended Data Table 1). b, The ensemble trimmed with IMBIE4 (1992–2017) estimates of ice mass change. c, The ensemble trimmed with IMBIE rates of ice mass change plus LIG sea-level constraints between 129 and 128 kyr ago34. d, The same as c, except with the addition of maximum mid-Pliocene sea-level constraints35,36 (Extended Data Fig. 1). Future ensembles in the main text (Fig. 1, Table 1) use the combined IMBIE + LIG + Pliocene history matching constraints as shown in d.

Source data

Extended Data Fig. 5 Future retreat of Thwaites Glacier (TG) and Pine Island Glacier (PIG) with +3 °C global warming.

The Amundsen Sea sector of the ice sheet in a nested, high-resolution (1 km) simulation using average calibrated values of hydrofracturing and ice-cliff calving parameters (CALVLIQ = 107 m−1 yr2; VCLIF = 7.7 km yr−1), consistent with those used in CESM1.2.2-forced simulations (Fig. 1h) and CDR simulations (Fig. 3, Table 1). a–c, The ice sheet in 2050. d–f, The ice sheet in 2100. a, d, Ice-sheet geometry and annually averaged ice-cliff calving rates at thick, weakly buttressed grounding lines. The solid line in all panels is the grounding line and the dashed line is its initial position. Note that simulated ice-cliff calving rates are generally much slower than the maximum allowable value of 7.7 km yr−1. Ice shelves downstream of calving ice cliffs are the equivalent of weak mélange, incapable of stopping calving64. b, e, Ice surface speed showing streaming and fast flow just upstream of calving ice cliffs where driving stresses are greatest. c, f, Change in ice thickness relative to the initial state. g, GMSL contributions within the nested domain at model spatial resolutions spanning 1–10 km.

Extended Data Fig. 6 Antarctic contribution to sea level under standard RCP forcing.

a–c, The fan charts show the time-evolving uncertainty and range around the median ensemble value (thick black line) in 10% increments. The RCP ensembles use the same IMBIE, LIG and Pliocene observational constraints applied to the simulations in Fig. 1. GMSL contributions in simulations without hydrofracturing or ice-cliff calving (excluded from the validated ensembles) are shown for East Antarctica (thin blue line), West Antarctica (thin red line) and the total Antarctic contribution (thin black line). a, RCP2.6; b, RCP4.5; and c, RCP8.5.

Source data

Extended Data Fig. 7 Long-term magnitudes and rates of GMSL rise contributed by Antarctica.

a, Ensemble median (50th percentile) projections of GMSL rise contributed by Antarctica with emissions forcing consistent with the +1.5 °C and +2.0 °C Paris Agreement ambitions, versus a +3.0 °C scenario closer to current NDCs. b, Median (50th percentile) rates of GMSL rise in the same emissions scenarios as in a, illustrating a sharp jump in ice loss in the warmer +3.0 °C scenario after 2060 (also see Fig. 1), and reduced net ice loss before 2060 (black line) caused by increased snowfall. c, Ensemble median (50th percentile) projections of GMSL rise contributed by Antarctica with emissions forcing consistent with standard RCP scenarios, highlighting the potential for extreme GMSL rise under high (RCP8.5) emissions. d, Ensemble median (50th percentile) rates of GMSL rise in the same RCP scenarios as shown in c. Note the much larger vertical-axis scales in c and d relative to a and b.

Extended Data Fig. 8 Coupled ice–Earth–sea level model simulations.

a–c, Simulations without hydrofracturing and ice-cliff calving processes. d–f, Simulations with hydrofracturing and ice-cliff calving enabled (Methods). GMSL contributions are from the WAIS only. Various Earth viscosity profiles (coloured lines) are compared with the ice-sheet model’s standard ELRA formulation (black line). The most extreme viscosity profile (blue line) assumes a thin lithosphere and very weak underlying mantle, like that observed in the Amundsen sea10, but extended continent-wide. a, RCP2.6 without hydrofracturing or ice-cliff calving. b, RCP2.6 with hydrofracturing and ice-cliff calving. c, RCP4.5 without hydrofracturing or ice-cliff calving. d, RCP4.5 with hydrofracturing and ice-cliff calving. e, RCP8.5 without hydrofracturing or ice-cliff calving. f, RCP8.5 with hydrofracturing and ice-cliff calving.

Extended Data Table 1 Model ensemble parameter values
Full size table
Extended Data Table 2 Antarctic sea-level contributions with alternative maximum ice-cliff calving rates
Full size table

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Supplementary Notes, Supplementary Figures 1–6, and Supplementary Tables 1–2. The Supplementary Information shows 1) uncertainty in future Antarctic climate forcing, 2) an alternative ice shelf hydrofracturing scheme, an improved formulation of buttressing at grounding lines, and 4) statistical emulation of our physical model ensembles.

Source data

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

DeConto, R.M., Pollard, D., Alley, R.B. et al. The Paris Climate Agreement and future sea-level rise from Antarctica. Nature 593, 83–89 (2021). https://doi.org/10.1038/s41586-021-03427-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-021-03427-0

This article is cited by

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

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing