Timing, pace and controls on ice sheet retreat: an introduction to the BRITICE‐CHRONO transect reconstructions of the British–Irish Ice Sheet

Abstract

Motivated to help improve the robustness of predictions of sea level rise, the BRITICE‐CHRONO project advanced knowledge of the former British–Irish Ice Sheet, from 31 to 15 ka, so that it can be used as a data‐rich environment to improve ice sheet modelling. The project comprised over 40 palaeoglaciologists, covering expertise in terrestrial and marine geology and geomorphology, geochronometric dating and the modelling of ice sheets and oceans. A systematic and directed campaign, organised across eight transects from the continental shelf edge to a short distance (10s of kilometres) onshore, was used to collect 914 samples which yielded 639 new ages, tripling the number of dated sites constraining the timing and rates of change of the collapsing ice sheet. This special issue synthesises these findings of ice advancing to the maximum extent and its subsequent retreat for each of the eight transects to produce definitive palaeogeographic reconstructions of ice margin positions across the marine to terrestrial transition. These results are used to understand the controls that drove or modulated ice sheet retreat. A further paper reports on how ice sheet modelling experiments and empirical data can be used in combination, and another probes the glaciological meaning of ice‐rafted debris.

Growth and retreat of the last British–Irish Ice Sheet, 31 000 to 15 000 years ago: the BRITICE‐CHRONO reconstruction

“…In summary, the BRITICE‐CHRONO project (logistics and participants described in Clark et al . 2021) sampled material for dating at 914 sites, on‐ and offshore, producing 690 new age assessments (338 radiocarbon; 162 luminescence and 190 cosmogenic) related to the advance or retreat of the ice sheet. A quality control exercise (Small et al .…”

GEORGIA: A Graph Neural Network Based EmulatOR for Glacial Isostatic Adjustment

“…We achieve this by collecting a wide range of ice history models for four different regions: North America (including Greenland), Eurasia, Antarctica, and all other regions with mountain glaciers (including Patagonia), and sampling the spatio‐temporal variability between different reconstructions. In total, we use four global ice models that predict ice‐sheet evolution in the four regions (Gowan et al., 2021; Lambeck et al., 2014; Peltier, 2004; Peltier et al., 2015), along with four North American (Gowan et al., 2016; Han et al., 2021; Roy & Peltier, 2018; Tarasov & Peltier, 2003; Tarasov et al., 2012), four Eurasian (Abe‐Ouchi et al., 2013; Clark et al., 2021; Han et al., 2021; Patton et al., 2016, 2017; Tarasov et al., 2014) and three Antarctic (Argus et al., 2014; Briggs et al., 2014; Whitehouse, Bentley, & Le Brocq, 2012; Whitehouse, Bentley, Milne, et al., 2012) ice models. Because these ice models are reconstructed based on different principles (e.g., thermomechanical ice modeling, GIA modeling, and the interpolation of glacial geomorphological data), they provide good coverage of possible ice‐sheet deglaciation uncertainty.…”

Patterns of glacio‐isostatic adjustment in mainland Scotland: new data from western central Scotland, proximal to the zone of maximum rebound

“…As the ice sheets in the Northern Hemisphere developed, ice, initially accumulating in mountainous areas, ultimately covered large lowland areas (Clark et al . 2021). Likewise, during ice wastage, the areas of maximum ice thickness reverted to the western centres of maximum precipitation rather than the central ice dome associated with the most extensive ice sheet.…”