Modelling the evolution of Ryder Glacier, Greenland, through the Holocene to investigate its responses to marine and atmospheric forcings.

Coupling paleo numerical simulations of the Greenland Ice Sheet with physical geological evidence of past ice sheet extent can greatly improve our understanding of the factors driving ice loss. Geological observations can be used to reconstruct the state of the Greenland Ice Sheet at snap shots in time, thus acting as constraints to test the fidelity of ice sheet models that can tell a continuous story of retreat over the same geologic timescales. Swedish Ice Breaker Oden’s visit to Sherard Osborn Fjord and Ryder Glacier in 2019 collected a plethora of marine-geological data that describes the glacier’s behaviour and retreat during the Holocene. Here we use a 3D thermo-coupled Higher-Order ice flow module incorporated in the Ice-sheet and Sea-level System Model (ISSM) to simulate the dynamics of Ryder Glacier from 12500 ka to present day. By focusing on a specific individual glacier, we can run the model at resolutions <1km near the grounding line to shed light on the marine (calving and submarine melt) and atmospheric factors that potentially drove Ryder’s retreat from its Younger Dryas position. Of particular interest is understanding whether the glacier withdrew from its marine setting during the Holocene Thermal Maximum and what conditions were required for Ryder to regrow its modern-day ice tongue during the neoglacial cooling at the end of the Holocene.