Holocene evolution of the Amundsen Sea sector from three-dimensional modelling constrained by extensive ice-penetrating radar isochrones

Whilst our understanding of the past ice-sheet extent of the Amundsen Sea sector at the Last Glacial Maximum (LGM) is relatively well known, the subsequent retreat (and potential re-advance) of Pine Island and Thwaites glaciers during the Holocene is contrastingly less understood. Some studies conducted across its neighbouring catchments, such as the Weddell and Ross Sea sectors, indicate that the grounding line may have retreated beyond its current position, and then subsequently re-advanced primarily due to isostatic rebound and stabilisation around pinning points. Over the Amundsen Sea sector, contrasting evidence suggests that non-linear changes in inland ice-sheet cover may have occurred, but little evidence exists for large changes affecting the continuous and gradual retreat of the grounding line from the LGM to its current position today. Here, we employ the three-dimensional PISM ice-sheet model to reconstruct the evolution of this sector since the LGM. We first explore the full parameter space using a Latin Hypercube Sampling method, and further constrain our best sets of simulations using extensive and newly available isochronal surfaces imaged by radars and dated at several snapshots throughout the last ~20 thousand years. We show that isochrones are essential for assessing the transient evolution of paleo simulations, particularly in off-divide areas of the ice sheet, and discuss how different geothermal heat-flux and SMB datasets impact the transient evolution of this sensitive sector.