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Ice sheet and climate processes driving the uncertainty in projections of future sea level rise: a structured expert judgement approach.
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  • Jonathan L. Bamber,
  • Michael Oppenheimer,
  • Robert E Kopp,
  • William P. Aspinall,
  • Roger Cooke
Jonathan L. Bamber
Bristol University

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Michael Oppenheimer
Princeton U
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Robert E Kopp
Rutgers University
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William P. Aspinall
University of Bristol
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Roger Cooke
Resources For The Future
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The ice sheets covering Antarctica and Greenland present the greatest uncertainty in, and largest potential contribution to, future sea level rise. The uncertainty arises from a paucity of suitable observations covering the full range of ice sheet behaviors, incomplete understanding of process influences, and limitations in defining key boundary conditions for the numerical models. To investigate the impact of these uncertainties on ice sheet projections we undertook a structured expert judgement study. Here, we interrogate the findings of that study to identify the dominant drivers of uncertainty in projections and their relative importance as a function of ice sheet and time. We find that for the 21st century, Greenland surface melting, in particular the role of surface albedo effects, and West Antarctic ice dynamics, specifically the role of ice shelf buttressing, dominate the uncertainty. The importance of these effects holds under both a high-end 5°C global warming scenario and another that limits global warming to 2°C. During the 22nd century the dominant drivers of uncertainty shift. Under the 5°C scenario, East Antarctic ice dynamics dominate the uncertainty in projections, driven by the possible role of ice flow instabilities. These dynamic effects only become dominant, however, for a temperature scenario above the Paris Agreement 2°C target and beyond 2100. Our findings identify key processes and factors that need to be addressed in future modeling studies in order to reduce uncertainties in ice sheet projections.
Oct 2022Published in Earth's Future volume 10 issue 10. 10.1029/2022EF002772