Greenland and Antarctic ice sheets and sea level rise

Researchers report estimates of Greenland and Antarctic ice sheet contributions to future sea level rise (SLR) based on expert judgments. SLR poses a threat to coastal communities and ecosystems, and adaptation strategies require quantitative projections of future SLR. Such projections remain challenging due to uncertainties regarding the fate of the Greenland and Antarctic ice sheets. Jonathan Bamber and colleagues estimated the probability distribution of future SLR using structured expert judgement, which has proved useful for estimating quantities that are difficult to model. The authors asked 22 experts on the Greenland and Antarctic ice sheets to provide plausible ranges for future ice accumulation, discharge, and surface runoff, and the dependencies between these variables, for each of the Greenland, West Antarctic, and East Antarctic ice sheets under low and high future global temperature rise scenarios. Aggregation of the experts' responses yielded probability distributions for future SLR with long upper tails, especially for the high-temperature scenario. Projections of global total SLR based on these results yielded a small but meaningful probability of SLR exceeding 2 m by the year 2100 under the high-temperature scenario, well above the likely upper limit presented in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. According to the authors, the results suggest that coastal communities should consider the possibility of 21st-century SLR in excess of 2 m in developing adaptation strategies.

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Article #18-17205: "Ice sheet contributions to future sea-level rise from structured expert judgment," by Jonathan L. Bamber, Michael Oppenheimer, Robert E. Kopp, Willy P. Aspinall, and Roger M. Cooke.

MEDIA CONTACT: Jonathan L. Bamber, University of Bristol, UNITED KINGDOM; tel: +44-117-4282490; e-mail: j.bamber@bristol.ac.uk

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