Geometry of the Meridional Overturning Circulation at the Last Glacial Maximum Academic Article uri icon

abstract

  • Abstract Understanding the contribution of ocean circulation to glacialinterglacial climate change is a major focus of paleoceanography. Specifically, many have tried to determine whether the volumes and depths of Antarctic- and North Atlanticsourced waters in the deep ocean changed at the Last Glacial Maximum (LGM; 2218 kyr BP) when atmospheric pCO2 concentrations were 100 ppm lower than the preindustrial. Measurements of sedimentary geochemical proxies are the primary way that these deep ocean structural changes have been reconstructed. However, the main proxies used to reconstruct LGM Atlantic water mass geometry provide conflicting results as to whether North Atlanticsourced waters shoaled during the LGM. Despite this, a number of idealized modeling studies have been advanced to describe the physical processes resulting in shoaled North Atlantic waters. This paper aims to critically assess the approaches used to determine LGM Atlantic circulation geometry and lay out best practices for future work. We first compile existing proxy data and paleoclimate model output to deduce the processes responsible for setting the ocean distributions of geochemical proxies in the LGM Atlantic Ocean. We highlight how small-scale mixing processes in the ocean interior can decouple tracer distributions from the large-scale circulation, complicating the straightforward interpretation of geochemical tracers as proxies for water mass structure. Finally, we outline promising paths toward ascertaining the LGM circulation structure more clearly and deeply.

published proceedings

  • JOURNAL OF CLIMATE

altmetric score

  • 10.6

author list (cited authors)

  • Pavia, F. J., Jones, C. S., & Hines, S. K.

citation count

  • 1

complete list of authors

  • Pavia, Frank J||Jones, C Spencer||Hines, Sophia K

publication date

  • September 2022