Constraining Last Interglacial ice sheet volumes through GIA-corrected sea-level reconstructions

Understanding the behaviour of polar ice sheets during past warm intervals provides critical constraints on their potential response to future warming scenarios. The Last Interglacial (LIG, ~125 ka) is a particularly valuable analogue, characterised by temperatures around 1-2°C above pre-industrial levels and global mean sea level 6-9 m higher than today. This study presents a comprehensive analysis integrating relative sea level (RSL) observations with numerical modelling to reconstruct ice volume fluctuations during this key interval.

A fundamental challenge in reconstructing past ice volumes from RSL records lies in deconvolving the spatially heterogeneous solid Earth deformation signals associated with Glacial Isostatic Adjustment (GIA) from the eustatic component. To address this, we have developed and implemented a high-resolution numerical model that explicitly accounts for GIA effects during the LIG. The integration of this model with a spatially extensive database of well-dated RSL indicators enables robust constraints on polar ice sheet volume changes.

This study utilises a GIA model, incorporating rotational effects, in order to predict variations in both space and time with respect to RSL during the LIG. The aim of this study is to evaluate the dependence of these predictions on penultimate glacial maximum ice geometries, by conducting a comparison with global RSL observations. The conclusions of this study serve to further the understanding of ice sheet response to warming, and thus inform future projections of sea level.