Skip to main content

Thank you for visiting 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.

  • Article
  • Published:

An expert judgement assessment of future sea level rise from the ice sheets


A major gap in predictive capability concerning the future evolution of the ice sheets was identified in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change. As a consequence, it has been suggested that the AR4 estimates of future sea-level rise from this source may have been underestimated. Various approaches for addressing this problem have been tried, including semi-empirical models and conceptual studies. Here, we report a formalized pooling of expert views on uncertainties in future ice-sheet contributions using a structured elicitation approach. We find that the median estimate of such contributions is 29 cm—substantially larger than in the AR4—while the upper 95th percentile value is 84 cm, implying a conceivable risk of a sea-level rise of greater than a metre by 2100. On the critical question of whether recent ice-sheet behaviour is due to variability in the ice sheet–climate system or reflects a long-term trend, expert opinion is shown to be both very uncertain and undecided.

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

Access options

Buy this article

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

Figure 1: Shaded relief maps of Antarctica and Greenland showing regions of enhanced flow (in colour) and areas of the ice sheets grounded below sea level (hatched).
Figure 2: The PDF for the rate of SLR due to ice-sheet contributions by year 2100.
Figure 3: PDFs for the contributions of each ice sheet derived from the 2012 survey, combined as distributions using the performance weights (PerfWts) pooling option.
Figure 4: PDFs of the 2010 and 2012 response to the question related to whether the trends observed in the satellite record over roughly the past decade is due to internal variability or to a secular trend.

Similar content being viewed by others


  1. Rignot, E., Velicogna, I., van den Broeke, M., Monaghan, A. & Lenaerts, J. Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophys. Res. Lett. 38, L05503 (2011).

    Article  Google Scholar 

  2. Holland, D. M., Thomas, R. H., de Young, B., Ribergaard, M. H. & Lyberth, B. Acceleration of Jakobshavn Isbrae triggered by warm subsurface ocean waters. Nature Geosci. 1, 659–664 (2008).

    Article  CAS  Google Scholar 

  3. Payne, A. J., Vieli, A., Shepherd, A. P., Wingham, D. J. & Rignot, E. Recent dramatic thinning of largest West Antarctic ice stream triggered by oceans. Geophys. Res. Lett. 31, L23401 (2004).

    Article  Google Scholar 

  4. Pritchard, H. D. et al. Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature 484, 502–505 (2012).

    Article  CAS  Google Scholar 

  5. Moon, T., Joughin, I., Smith, B. & Howat, I. 21st-century evolution of Greenland outlet glacier velocities. Science 336, 576–578 (2012).

    Article  CAS  Google Scholar 

  6. Andresen, C. S. et al. Rapid response of Helheim Glacier in Greenland to climate variability over the past century. Nature Geosci. 5, 37–41 (2012).

    Article  CAS  Google Scholar 

  7. Joughin, I., Abdalati, W. & Fahnestock, M. Large fluctuations in speed on Greenland’s Jakobshavn Isbrae glacier. Nature 432, 608–610 (2004).

    Article  CAS  Google Scholar 

  8. Vaughan, D. G. & Arthern, R. Why is it hard to predict the future of ice sheets? Science 315, 1503–1504 (2007).

    Article  CAS  Google Scholar 

  9. Cooke, R. M. Experts in Uncertainty-Opinion and Subjective Probability in Science (Oxford Univ. Press, 1991).

    Google Scholar 

  10. Aspinall, W. A route to more tractable expert advice. Nature 463, 294–295 (2010).

    Article  CAS  Google Scholar 

  11. Smith, J. B. et al. Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) reasons for concern. Proc. Natl Acad. Sci. USA 106, 4133–4137 (2009).

    Article  CAS  Google Scholar 

  12. Zickfeld, K. et al. Expert judgements on the response of the Atlantic meridional overturning circulation to climate change. Climatic Change 82, 235–265 (2007).

    Article  CAS  Google Scholar 

  13. Cooke, R. M. & Goossens, L. TU Delft expert judgment data base. Reliab. Eng. Syst. Saf. 93, 657–674 (2008).

    Article  Google Scholar 

  14. Van den Broeke, M. et al. Partitioning recent Greenland mass loss. Science 326, 984–986 (2009).

    Article  CAS  Google Scholar 

  15. Hellmer, H. H., Kauker, F., Timmermann, R., Determann, J. & Rae, J. Twenty-first-century warming of a large Antarctic ice-shelf cavity by a redirected coastal current. Nature 485, 225–228 (2012).

    Article  CAS  Google Scholar 

  16. Gregory, J. M. & Huybrechts, P. Ice-sheet contributions to future sea-level change. Phil. Trans. R. Soc. A 364, 1709–1731 (2006).

    Article  CAS  Google Scholar 

  17. Fettweis, X., Hanna, E., Gallee, H., Huybrechts, P. & Erpicum, M. Estimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries. Cryosphere 2, 117–129 (2008).

    Article  Google Scholar 

  18. Radic, V. & Hock, R. Regionally differentiated contribution of mountain glaciers and ice caps to future sea-level rise. Nature Geosci. 4, 91–94 (2011).

    Article  CAS  Google Scholar 

  19. Meehl, G. A. et al. Relative outcomes of climate change mitigation related to global temperature versus sea-level rise. Nature Clim. Change 2, 576–580 (2012).

    Article  Google Scholar 

  20. Moss, R. H. et al. The next generation of scenarios for climate change research and assessment. Nature 463, 747–756 (2010).

    Article  CAS  Google Scholar 

  21. Schaeffer, M., Hare, W., Rahmstorf, S. & Vermeer, M. Long-term sea-level rise implied by 1.5 °C and 2 °C warming levels. Nature Clim. Change 2, 867–870.

  22. Meehl, G. A. et al. in IPCC Climate Change 2007: The Physical Science Basis (ed. Solomon, S.) Ch. 10 (Cambridge Univ. Press, 2007).

    Google Scholar 

  23. Nicholls, R. J. et al. Sea-level rise and its possible impacts given a ‘beyond 4 degrees C world’ in the twenty-first century. Philos. Trans. R. Soc. A 369, 161–181 (2011).

    Article  Google Scholar 

Download references


We thank the experts who participated in the two surveys. Each is a pre-eminent scientist in the field, with many other demands on their time and expertise; their individual views are authoritative, and collectively invaluable. J.L.B. would like to thank M. New and J. Sky for their assistance with the first questionnaire and D. Vaughan for his comments on a draft of the paper. This work was largely funded by the European Commission’s 7th Framework Programme through grant number 226375 (ice2sea contribution number 129). W.P.A. was supported in part by an Advanced European Research Council grant to Prof RSJ Sparks (VOLDIES Project).

Author information

Authors and Affiliations



J.L.B. conceived and carried out the study and solicited the expert judgements. W.P.A. analysed the elicitations and carried out the Monte Carlo simulations. Both authors wrote the paper.

Corresponding author

Correspondence to J. L. Bamber.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1176 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bamber, J., Aspinall, W. An expert judgement assessment of future sea level rise from the ice sheets. Nature Clim Change 3, 424–427 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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