Projecting Antarctica's contribution to future sea level rise from basal ice shelf melt using linear response functions of 16 ice sheet models (LARMIP-2)

• Main Authors: Levermann, Anders, Winkelmann, Ricarda, Albrecht, Torsten, Goelzer, Heiko, Golledge, Nicholas R., Greve, Ralf, Huybrechts, Philippe, Jordan, Jim, Leguy, Gunter, Martin, Daniel, Morlighem, Mathieu, Pattyn, Frank, Pollard, David, Quiquet, Aurelien, Rodehacke, Christian, Seroussi, Helene, Sutter, Johannes, Zhang, Tong, Van Breedam, Jonas, Calov, Reinhard, DeConto, Robert, Dumas, Christophe, Garbe, Julius, Gudmundsson, G. Hilmar, Hoffman, Matthew J., Humbert, Angelika, Kleiner, Thomas, Lipscomb, William H., Meinshausen, Malte, Ng, Esmond, Nowicki, Sophie M. J., Perego, Mauro, Price, Stephen F., Saito, Fuyuki, Schlegel, Nicole-Jeanne, Sun, Sainan, van de Wal, Roderik S W
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Sciences exactes et naturelles; Antarctic; Southern Ocean; The Antarctic; Antarc*; Ice Sheet; Ice Shelf
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/303021; https://dipot.ulb.ac.be/dspace/bitstream/2013/303021/1/doi_286665.pdf

Abstract. The sea level contribution of the Antarctic ice sheetconstitutes a large uncertainty in future sea level projections. Here weapply a linear response theory approach to 16 state-of-the-art ice sheetmodels to estimate the Antarctic ice sheet contribution from basal ice shelfmelting within the 21st century. The purpose of this computation is toestimate the uncertainty of Antarctica's future contribution to global sealevel rise that arises from large uncertainty in the oceanic forcing and theassociated ice shelf melting. Ice shelf melting is considered to be a majorif not the largest perturbation of the ice sheet's flow into the ocean.However, by computing only the sea level contribution in response to iceshelf melting, our study is neglecting a number of processes such assurface-mass-balance-related contributions. In assuming linear responsetheory, we are able to capture complex temporal responses of the ice sheets,but we neglect any self-dampening or self-amplifying processes. This isparticularly relevant in situations in which an instability is dominating theice loss. The results obtained here are thus relevant, in particular wherever theice loss is dominated by the forcing as opposed to an internal instability,for example in strong ocean warming scenarios. In order to allow forcomparison the methodology was chosen to be exactly the same as in anearlier study (Levermannet al. 2014) but with 16 instead of 5 ice sheet models. We includeuncertainty in the atmospheric warming response to carbon emissions (fullrange of CMIP5 climate model sensitivities), uncertainty in the oceanictransport to the Southern Ocean (obtained from the time-delayed and scaledoceanic subsurface warming in CMIP5 models in relation to the global meansurface warming), and the observed range of responses of basal ice shelfmelting to oceanic warming outside the ice shelf cavity. This uncertainty inbasal ice shelf melting is then convoluted with the linear responsefunctions of each of the 16 ice sheet models to obtain the ice flow ...