Geometry of the Meridional Overturning Circulation at the Last Glacial Maximum

Abstract Understanding the contribution of ocean circulation to glacial–interglacial climate change is a major focus paleoceanography. Specifically, many have tried determine whether volumes and depths Antarctic- North Atlantic–sourced waters in deep changed at Last Glacial Maximum (LGM; ∼22–18 kyr BP) when atmospheric p CO 2 concentrations were 100 ppm lower than preindustrial. Measurements sedimentary geochemical proxies are primary way that these structural changes been reconstructed. However, main used reconstruct LGM Atlantic water mass geometry provide conflicting results as shoaled during LGM. Despite this, number idealized modeling studies advanced describe physical processes resulting waters. This paper aims critically assess approaches lay out best practices for future work. We first compile existing proxy data paleoclimate model output deduce responsible setting distributions Ocean. highlight how small-scale mixing interior can decouple tracer from large-scale circulation, complicating straightforward interpretation tracers structure. Finally, we outline promising paths toward ascertaining structure more clearly deeply.