A Gaussian process emulator for simulating ice sheet-climate interactions on a multi-million year timescale: CLISEMv1.0

Abstract. On multi-million year timescales, fully coupled ice sheet – climate simulations are hampered by computational limitations, even at coarser resolutions and when considering asynchronous coupling schemes. In this study, a novel coupling method CLISEMv1.0 (CLimate-Ice Sheet EMulator version 1.0) is presented where a Gaussian process emulator is applied to the climate model HadSM3 coupled to the ice sheet model AISMPALEO. The temperature and precipitation fields from HadSM3 are emulated to feed the mass balance model from AISMPALEO. The sensitivity of the evolution of the ice sheet over time is tested to the number of predefined ice sheet geometries the emulator is calibrated on, to the formulation of the ice sheet parameter (being either ice sheet volume, either ice sheet area, or both) and to the coupling time. Sensitivity experiments are conducted to explore the uncertainty introduced by the emulator. Additionally, different lapse rate adjustments are used between the relatively coarse climate model and the much finer ice sheet model topography. It is shown that the ice sheet evolution over a million-year timescale is strongly sensitive to the definition of the ice sheet parameter and to the number of predefined ice sheet geometries. With the new coupling procedure, we provide a computationally efficient framework for simulating ice sheet-climate interactions on a multi-million year timescale that allows for a large number of sensitivity tests.