Climate sensitivity of western Antarctic Peninsula ice shelves (CSAPIS)

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Most ice shelves on the western Antarctic Peninsula show or have experienced considerable retreat or even complete disintegration in the last few decades. Recent studies have linked this partly to upwelling of warm Circumpolar Deep Water (CDW), which is supposed to influence particularly the southwestern Antarctic Peninsula region. However, the exact processes and mechanisms as well as the sensitivity of the region to further ice shelf and glacier thinning and retreat are not known or not well constrained. This is partly because of lacking observations and the demanding modelling efforts. In this study, we propose to analyse time series of remote sensing data to derive various glaciological variables such as surface velocities, surface elevation change, grounding line and ice front positions as well as structural variables. We will provide this analysis for entire large-scale catchments on the southwestern Antarctic Peninsula. We will combine the remote sensing data sets to compute temporally high-resolution ice mass discharge estimates with two independent methods. Those data sets will form a contribution to international efforts such as Ice sheet Mass Balance Inter-comparison Exercise (IMBIE) or the next report of the Intergovernmental Panel of Climate Change (IPCC). The above-mentioned remote sensing products will then be used for calibration and validation in forward simulations for the ice shelve retreat in the region with an ice dynamic model. The employed ice flow model is the Ice-Sheet and Sea-level system model (ISSM) in Blatter-Pattyn approximation and an envisaged resolution down to 200-500 m at the grounding line. The aim of the numerical modelling studies is two-fold. In a first step, the mechanisms for recent ongoing changes are investigated. Here, we focus on the importance of ice-shelf buttressing and the impact of ice shelf melting (ice-ocean interaction). This step heavily builds on remote sensing products assessing the quality of the transient simulations. In a second step, the future stability of ice shelves and glacier tributaries is estimated. In accordance with the COordinated Regional Downscaling EXperiment (Polar-CORDEX) modelling strategy, the focus is on the Representative Concentration Pathway (RCP) 8.5 scenario. To tackle these questions, we will rely on suitable oceanic and atmospheric fields. In particular, we strive to use data-sets of the ongoing efforts with the Finite Element Sea ice-Ocean Model (FESOM) to include ice shelf cavities in the modelling framework (ongoing ECHAM6-FESOM coupling for the Climate Model Intercomparison Project (CMIP) 6 and from the Polar-CORDEX activity).