Periodic Reporting for period 3 - PALGLAC (Palaeoglaciological advances to understand Earth’s ice sheets by landform analysis)
Période du rapport: 2021-10-01 au 2023-03-31
Focussing on the most numerous and spatially-extensive records of palaeo ice sheet activity - glacial landforms - the project aims to revolutionise understanding of past, present and future ice sheets. Our mapping campaign (Work-Package 1), complemented by machine learning techniques (WP2), and will vastly increase the evidence-base. Resolution of how subglacial landforms are generated and how hydrological networks develop (WP3) would be major breakthroughs leading with key implications for ice flow models and hydrological effects on ice dynamics. By pioneering techniques and coding for combining ice sheet models with landform data (WP4) we will improve knowledge of the role of palaeo-ice sheets in Earth system change. Trialling of numerical models in these data-rich environments will highlight deficiencies in process-formulations, leading to better models.
Example figure: From landform mapping and analysis we built a model and scaling metrics of how subglacial water pressurisation can overwhelm the host drainage conduit, with water expanding laterally across the bed, important for controlling ice flow speeds (from Lewington et al 2020).
Prior to the pandemic we conducted fieldwork in a remote part of NE Greenland and now have samples for dating ice sheet retreat, but our other field activities across northern Europe have been delayed. We have advanced modelling of the creation and development of glacial landforms notably: 1) sedimentation in subglacial water pipes (regarding eskers); 2) spatial and temporal transitions between drumlins and subglacial ribs; and 3) tunnel valleys, subglacial ribs and ice marginal fans. Two papers report on these results and a further two are in final preparation.
On the PalGlac focus on data-modelling integration, two approaches have been devised, coded, published and used in action, namely, 1) scoring ice sheet model performance against observational evidence; 2) using observational evidence to directly nudge or correct model simulations, and another approach just started, 3) using evidence and model simulations to build a statistical emulator of ice sheet models that can advance approaches for modelling experiments. Data-constrained numerical modelling of the British-Irish and Scandinavian ice sheets have been used in glacio-isostatic modelling (i.e. ice mass loading of the lithosphere) to simulate relative sea level variation of the last deglaciation. These results have been used in six publications including one on forecasting 21st century sea levels around Britain and NW Europe.