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Evolving Understanding of Antarctic Ice-Sheet Physics and Ambiguity in Probabilistic Sea-Level ProjectionsMechanisms such as ice-shelf hydrofracturing and ice-cliff collapse may rapidly increase discharge from marine-based ice sheets. Here, we link a probabilistic framework for sea-level projections to a small ensemble of Antarctic ice-sheet (AIS) simulations incorporating these physical processes to explore their influence on global-mean sea-level (GMSL) and relative sea-level (RSL). We compare the new projections to past results using expert assessment and structured expert elicitation about AIS changes. Under high greenhouse gas emissions (Representative Concentration Pathway [RCP] 8.5), median projected 21st century GMSL rise increases from 79 to 146 cm. Without protective measures, revised median RSL projections would by 2100 submerge land currently home to 153 million people, an increase of 44 million. The use of a physical model, rather than simple parameterizations assuming constant acceleration of ice loss, increases forcing sensitivity: overlap between the central 90% of simulations for 2100 for RCP 8.5 (93-243 cm) and RCP 2.6 (26-98 cm) is minimal. By 2300, the gap between median GMSL estimates for RCP 8.5 and RCP 2.6 reaches >10 m, with median RSL projections for RCP 8.5 jeopardizing land now occupied by 950 million people (versus 167 million for RCP 2.6). The minimal correlation between the contribution of AIS to GMSL by 2050 and that in 2100 and beyond implies current sea-level observations cannot exclude future extreme outcomes. The sensitivity of post-2050 projections to deeply uncertain physics highlights the need for robust decision and adaptive management frameworks.
Document ID
20180000708
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kopp, Robert E. (Rutgers Univ. New Brunswick, NJ, United States)
DeConto, Robert M. (Massachusetts Univ. Amherst, MA, United States)
Bader, Daniel A. (Columbia Univ. New York, NY, United States)
Hay, Carling C. (Boston Coll. Boston, MA, United States)
Horton, Radley M. (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Kulp, Scott (Climate Central, Inc. Princeton, NJ, United States)
Oppenheimer, Michael (Princeton Univ. Princeton, NJ, United States)
Pollard, David (Pennsylvania State Univ. University Park, PA, United States)
Strauss, Benjamin (Climate Central, Inc. Princeton, NJ, United States)
Date Acquired
January 25, 2018
Publication Date
December 14, 2017
Publication Information
Publication: Earth's Future
Volume: 5
Issue: 12
ISSN: 2328-4277
Subject Category
Geosciences (General)
Report/Patent Number
GSFC-E-DAA-TN50811
Funding Number(s)
CONTRACT_GRANT: OCE-1202632
CONTRACT_GRANT: AGS 1203910/1203792
CONTRACT_GRANT: 80NSSC17M0057
CONTRACT_GRANT: ICER-1664013/1663693
CONTRACT_GRANT: ICER-1663807
Distribution Limits
Public
Copyright
Other