Ice sheet contributions to future sea-level rise from structured expert judgment

Jonathan L. Bamber, Michael Oppenheimer, Robert E. Kopp, Willy P. Aspinall, Roger M. Cooke

Research output: Contribution to journalArticle (Academic Journal)

66 Citations (Scopus)
158 Downloads (Pure)

Abstract

Despite considerable advances in process understanding, numerical modeling, and the observational record of ice sheet contributions to global mean sea-level rise (SLR) since the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change, severe limitations remain in the predictive capability of ice sheet models. As a consequence, the potential contributions of ice sheets remain the largest source of uncertainty in projecting future SLR. Here, we report the findings of a structured expert judgement study, using unique techniques for modeling correlations between inter- and intra-ice sheet processes and their tail dependences. We find that since the AR5, expert uncertainty has grown, in particular because of uncertain ice dynamic effects. For a +2 °C temperature scenario consistent with the Paris Agreement, we obtain a median estimate of a 26 cm SLR contribution by 2100, with a 95th percentile value of 81 cm. For a +5 °C temperature scenario more consistent with unchecked emissions growth, the corresponding values are 51 and 178 cm, respectively. Inclusion of thermal expansion and glacier contributions results in a global total SLR estimate that exceeds 2 m at the 95th percentile. Our findings support the use of scenarios of 21st century global total SLR exceeding 2 m for planning purposes. Beyond 2100, uncertainty and projected SLR increase rapidly. The 95th percentile ice sheet contribution by 2200, for the +5 °C scenario, is 7.5 m as a result of instabilities coming into play in both West and East Antarctica. Introducing process correlations and tail dependences increases estimates by roughly 15%.

Original languageEnglish
Pages (from-to)11195-11200
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume166
Issue number23
DOIs
Publication statusPublished - 20 May 2019

Structured keywords

  • GlobalMass

Keywords

  • Antarctica
  • Climate predictions
  • Greenland
  • Ice sheets
  • Sea-level rise

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