Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project)

• Published in: Journal of Glaciology
• Main Authors: Bindschadler, Robert A, Nowicki, Sophie, Abe-Ouchi, Ayako, Aschwanden, Andy, Choi, Hyeungu, Fastook, Jim, Granzow, Glen, Greve, Ralf, Gutowski, Gail, Herzfeld, Ute, Jackson, Charles, Johnson, Jesse, Khroulev, Constantine, Levermann, Anders, Lipscomb, William H, Martin, Maria A, Morlighem, Mathieu, Parizek, Byron R, Pollard, David, Price, Stephen F, Ren, Diandong, Saito, Fuyuki, Sato, Tatsuru, Seddik, Hakime, Seroussi, Helene, Takahashi, Kunio, Walker, Ryan, Wang, Wei L
• Format: Article in Journal/Newspaper
• Language: English
• Published: eScholarship, University of California 2013
• Subjects: Physical Sciences and Mathematics; climate forcing; glacier mass balance; ice sheet; ice shelf; interpolation; melting; numerical model; sea level change; sensitivity analysis; Antarctica; Arctic; Greenland; Antarctic; Antarc*; glacier; Ice Sheet; Ice Shelf; Journal of Glaciology
• Online Access: http://www.escholarship.org/uc/item/0gz6g1cc

Ten ice-sheet models are used to study sensitivity of the Greenland and Antarctic ice sheets to prescribed changes of surface mass balance, sub-ice-shelf melting and basal sliding. Results exhibit a large range in projected contributions to sea-level change. In most cases, the ice volume above flotation lost is linearly dependent on the strength of the forcing. Combinations of forcings can be closely approximated by linearly summing the contributions from single forcing experiments, suggesting that nonlinear feedbacks are modest. Our models indicate that Greenland is more sensitive than Antarctica to likely atmospheric changes in temperature and precipitation, while Antarctica is more sensitive to increased ice-shelf basal melting. An experiment approximating the Intergovernmental Panel on Climate Change's RCP8.5 scenario produces additional first-century contributions to sea level of 22.3 and 8.1 cm from Greenland and Antarctica, respectively, with a range among models of 62 and 14 cm, respectively. By 200 years, projections increase to 53.2 and 26.7 cm, respectively, with ranges of 79 and 43 cm. Linear interpolation of the sensitivity results closely approximates these projections, revealing the relative contributions of the individual forcings on the combined volume change and suggesting that total ice-sheet response to complicated forcings over 200 years can be linearized.