Role of model initialization for projections of 21st-century Greenland ice sheet mass loss

Published: Nov 1, 2014 by The PISM Authors

Three cross sections (north, center, south) through the modeled initial states, at a 5 km resolution.

This paper assesses the sensitivity of projections of Greenland ice sheet contribution to 21st-century sea-level rise to the model initial state. Four initialization methods are applied using PISM. The simulated contribution to sea-level rise by 2100 ranges from an equivalent of 0.2 to 6.8 cm. The largest uncertainties arise from different formulations of the regional climate models (0.8–3.9 cm) and applied scenarios (0.65–1.9 cm), but an important source of uncertainty is the initialization method (0.1–0.8 cm). These model simulations do not account for the recently observed acceleration of outlet glaciers and consequent thinning rates, ocean forcing, or the feedback occurring between ice-sheet elevation changes and climate forcing. These results should be considered a lower limit of Greenland ice sheet contributions to sea-level rise, until such processes have been integrated into large-scale ice-sheet models.