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

Published: Mar 1, 2013 by The PISM Authors

Two versions of PISM were among the ten ice sheet models 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 sea-level-relevant ice volume 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 non-linear feedbacks are modest. Our models indicate that Greenland is more sensitive than Antarctica to likely atmospheric changes in temperature and precipitation, while Antarctica is most sensitive to increased ice-shelf basal melting. An experiment approximating the IPCC’s RCP8.5 scenario produces 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.