Minimal change in Antarctic Circumpolar Current flow speed between the last glacial and Holocene

I N Mccave,G Kuhn,C-D Hillenbrand,M P Meredith,S J Crowhurst

doi:10.1038/ngeo2037

Abstract

Relatively little is known about the dynamics of the Antarctic Circumpolar Current during the last glacial period. Estimates of current speeds over the past 20,000 years based on sediment grain size suggest that average flow speeds during the last glacial were comparable to modern speeds, but not in the areas with overlying winter sea ice.

Highlights

Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen
Flow at the last glacial maximum was significantly slower in the southern ice-covered portion of the area[12], and faster in the north, which implicates shielding from wind stress by perennial sea-ice in the southern part of the current
These inferences are based on Holocene and last glacial maximum averages of the Sortable Silt mean grain size[13] for 12 cores across the Scotia Sea

Summary

Introduction

Flow at the last glacial maximum was significantly slower in the southern ice-covered portion of the area[12] (south of 56° S), and (non-significantly) faster in the north, which implicates shielding from wind stress by perennial sea-ice in the southern part of the current. These inferences are based on Holocene and last glacial maximum averages of the Sortable Silt mean grain size[13] for 12 cores across the Scotia Sea. Because momentum imparted at the surface is balanced at depth by topographic form drag, relative invariance of the bottom speeds argues against substantial changes in wind stress.

Results

Conclusion