Review of the paper by Pollard et al.

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> North Sea Last Interglacial sea level is sensitive to the fingerprint of mass loss from polar ice sheets. However, the signal is complicated by the influence of glacial isostatic adjustment driven by the Penultimate Glacial Period Eurasian ice sheet and its geometry remain significantly uncertain. Here, we produce new reconstructions of the Eurasian ice sheet during the Penultimate Glacial Maximum (PGM), for use as input to sea-level and climate models, by employing large ensemble experiments from a simple ice-sheet model that depends solely on basal sheer stress, ice extent, and topography. To explore the range of uncertainty in possible ice geometries, we use a parameterised shear-stress map as input that has been developed to incorporate bedrock characteristics and ice-sheet basal processes. We perform Bayesian uncertainty quantification to calibrate against global ice-sheet reconstructions of the last deglaciation to rule out combinations of input parameters that produce unrealistic ice sheets. The refined parameter space is then applied to the PGM to create an ensemble of plausible 3D Eurasian ice-sheet geometries. Our reconstructed PGM Eurasian ice-sheet volume is 51.16&plusmn;6.13 m sea-level equivalent which suggests a 14.3 % reduction in the volume of the PGM Laurentide ice-sheet. We find that the Barents-Kara Sea region displays both the largest mean volume and relative variability of 26.80 &plusmn; 3.58 m SLE while the British-Irish sector&rsquo;s volume of 1.77 &plusmn; 0.11 m SLE is smallest, yet most implausible. Our new workflow may be applied to other locations and periods where ice-sheet histories have limited empirical data.