title: Probabilistic framework for assessing the ice sheet contribution to sea level change.
abstract: Previous sea level rise (SLR) assessments have excluded the potential for dynamic ice loss over much of Greenland and Antarctica, and recently proposed "upper bounds" on Antarctica's 21st-century SLR contribution are derived principally from regions where present-day mass loss is concentrated (basin 15, or B15, drained largely by Pine Island, Thwaites, and Smith glaciers). Here, we present a probabilistic framework for assessing the ice sheet contribution to sea level change that explicitly accounts for mass balance uncertainty over an entire ice sheet. Applying this framework to Antarctica, we find that ongoing mass imbalances in non-B15 basins give an SLR contribution by 2100 that: (i) is comparable to projected changes in B15 discharge and Antarctica's surface mass balance, and (ii) varies widely depending on the subset of basins and observational dataset used in projections. Increases in discharge uncertainty, or decreases in the exceedance probability used to define an upper bound, increase the fractional contribution of non-B15 basins; even weak spatial correlations in future discharge growth rates markedly enhance this sensitivity. Although these projections rely on poorly constrained statistical parameters, they may be updated with observations and/or models at many spatial scales, facilitating a more comprehensive account of uncertainty that, if implemented, will improve future assessments.
authors: Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544, USA. cmlittle@princeton.edu
authors: Christopher M
authors: CM
authors: Little
authors: Nathan M
authors: NM
authors: Urban
authors: Michael
authors: M
authors: Oppenheimer
mesh_terms: D000864:Antarctic Regions; D057231:Climate Change; D046448:Ice Cover; D009792:Oceans and Seas; D011336:Probability
references: Proc Natl Acad Sci U S A. 2012 Dec 4;109(49):19934-7
references: 23169646
references: Science. 2010 Jun 18;328(5985):1517-20
references: 20558707
references: Science. 1999 Oct 8;286(5438):280-283
references: 10514369
references: Science. 2007 Sep 14;317(5844):1505-6
references: 17872430
references: Science. 2011 Jul 29;333(6042):620-3
references: 21798947
references: Science. 2008 Sep 5;321(5894):1340-3
references: 18772435
references: Science. 2009 May 15;324(5929):901-3
references: 19443778
references: Nature. 2012 Apr 25;484(7395):502-5
references: 22538614
references: Science. 2012 May 4;336(6081):551-2
references: 22556242
references: Science. 2012 Nov 30;338(6111):1183-9
references: 23197528
references: Science. 2012 May 4;336(6081):550-1
references: 22556241
references: Proc Natl Acad Sci U S A. 2011 May 31;108(22):8978-83
references: 21576500
references: Science. 2009 Feb 6;323(5915):753
references: 19197056
references: Nature. 2012 May 09;485(7397):225-8
references: 22575964
references: Nature. 2009 Mar 19;458(7236):329-32
references: 19295608