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Tuesday, May 17, 2011

"Committed sea-level rise for the next century from Greenland ice sheet dynamics during the past decade" by S. F. Price, A. J. Payne, I. M. Howat & B. E. Smith, PNAS, May 16, 2011

Proceedings of the National Academy of Sciences, published online before print May 16, 2011; doi: 10.1073/pnas.1017313108

Committed sea-level rise for the next century from Greenland ice sheet dynamics during the past decade

  1. Stephen F. Pricea,*
  2. Antony J. Payneb
  3. Ian M. Howatc, and 
  4. Benjamin E. Smithd
+Author Affiliations
  1. aFluid Dynamics and Solid Mechanics Group, Los Alamos National Laboratory, T3 MS B216, Los Alamos, NM 87545;
  2. bBristol Glaciology Centre, University of Bristol, University Road, Clifton, Bristol BS8 1SS, United Kingdom;
  3. cSchool of Earth Sciences, Ohio State University, 125 South Oval Mall, Columbus, OH 43210; and
  4. dPolar Science Center, Applied Physics Laboratory, University of Washington, Box 35560, Seattle, WA 98105
  1. Edited by Hans-Joachim Schellnhuber, Potsdam Institute for Climate Impact Research, Potsdam, Germany, and approved April 19, 2011 (received for review November 22, 2010)


We use a three-dimensional, higher-order ice flow model and a realistic initial condition to simulate dynamic perturbations to the Greenland ice sheet during the last decade and to assess their contribution to sea level by 2100. Starting from our initial condition, we apply a time series of observationally constrained dynamic perturbations at the marine termini of Greenland’s three largest outlet glaciers, Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. The initial and long-term diffusive thinning within each glacier catchment is then integrated spatially and temporally to calculate a minimum sea-level contribution of approximately 1 ± 0.4 mm from these three glaciers by 2100. Based on scaling arguments, we extend our modeling to all of Greenland and estimate a minimum dynamic sea-level contribution of approximately 6 ± 2 mm by 2100. This estimate of committed sea-level rise is a minimum because it ignores mass loss due to future changes in ice sheet dynamics or surface mass balance. Importantly, > 75% of this value is from the long-term, diffusive response of the ice sheet, suggesting that the majority of sea-level rise from Greenland dynamics during the past decade is yet to come. Assuming similar and recurring forcing in future decades and a self-similar ice dynamical response, we estimate an upper bound of 45 mm of sea-level rise from Greenland dynamics by 2100. These estimates are constrained by recent observations of dynamic mass loss in Greenland and by realistic model behavior that accounts for both the long-term cumulative mass loss and its decay following episodic boundary forcing.

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