Barystatic sea-level changes since the last glacial maximum

Abstract

Barystatic sea-level (BSL) defines a uniform alteration in the height of the ocean surface without considering the impacts of oceanic and atmospheric dynamics, gravitational, rotational and deformation effects induced by ice-ocean mass exchange. As a direct indicator of global ice volume change, quantifying BSL through time is important for calibrating the marine oxygen isotope record and understanding the relationship between past sea-level and climate change. However, due to the spatially variable nature of sea level change and sparse palaeo sea-level observations, BSL is not directly measurable, instead it can only be inferred by comparing geophysical model with sea-level observations. In this chapter, we review some concepts about calculating postglacial sea-level change and estimating BSL using a glacial isostatic adjustment (GIA) model, with a particular focus on BSL change since the Last Glacial Maximum (LGM). We provide data-model comparison between three commonly used GIA models and past sea-level data, which suggests the LGM is characterized by a 125–135m lowstand between ∼26 and ∼21.5ka BP, followed by rapid BSL rise until ∼7ka BP, with rates peaking at 20–40mmyear−1 around meltwater pulse 1a (14.65ka BP).