Ice sheet contributions to future sea-level rise from structured expert judgment
- PMID: 31110015
- PMCID: PMC6561295
- DOI: 10.1073/pnas.1817205116
Ice sheet contributions to future sea-level rise from structured expert judgment
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%.
Keywords: Antarctica; Greenland; climate predictions; ice sheets; sea-level rise.
Copyright © 2019 the Author(s). Published by PNAS.
Conflict of interest statement
The authors declare no conflict of interest.
Figures



References
-
- Oppenheimer M., Little C. M., Cooke R. M., Expert judgement and uncertainty quantification for climate change. Nat. Clim. Chang. 6, 445–451 (2016).
-
- Kopp R. E., et al. , Probabilistic 21st and 22nd century sea-level projections at a global network of tide-gauge sites. Earths Future 2, 383–406 (2014).
-
- Bamber J. L., Westaway R. M., Marzeion B., Wouters B., The land ice contribution to sea level during the satellite era. Environ. Res. Lett. 13, 063008 (2018).
-
- WCRP Global Sea Level Budget Group , Global sea level budget 1993-present. Earth Syst. Sci. Data 10, 1551–1590 (2018).
Publication types
Grants and funding
LinkOut - more resources
Full Text Sources
Research Materials