Strong glacial-interglacial variability in upper ocean hydrodynamics, biogeochemistry, and productivity in the southern Indian Ocean


Deborah Tangunan, Universidad de Salamanca
Deborah Tangunan, Universidad de Salamanca
Melissa A. Berke, University of Notre Dame
Alejandra Cartagena-Sierra, University of Notre Dame
José Abel Flores, Universidad de Salamanca
Jens Gruetzner, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
Francisco Jiménez-Espejo, Consejo Superior de Investigaciones Científicas
Leah J. LeVay, Texas A&M University
Karl Heinz Baumann, Universität Bremen
Oscar Romero, MARUM – Zen­trum für Ma­ri­ne Um­welt­wis­sen­schaf­ten
Mariem Saavedra-Pellitero, University of Birmingham
Jason J. Coenen, Northern Illinois University
Aidan Starr, Cardiff University
Sidney R. Hemming, Lamont-Doherty Earth Observatory
Ian R. Hall, Cardiff University
Stephen Barker, Cardiff University
Luna Brentegani, Queensland University of Technology
Thibaut Caley, Université de Bordeaux
Christopher D. Charles, Scripps Institution of Oceanography
Julien G. Crespin, Université de Bordeaux
Allison M. Franzese, Hostos Community College
Xibin Han, Ministry of Natural Resources of the People's Republic of China
Sophia K.V. Hines, Lamont-Doherty Earth Observatory
Francisco J. Jimenez Espejo, Consejo Superior de Investigaciones Científicas
Janna Just, Universität Bremen
Andreas Koutsodendris, Universität Heidelberg
Kaoru Kubota, University of Tokyo
Nambiyathodi Lathika, National Centre for Polar and Ocean Research
Richard D. Norris, Scripps Institution of Oceanography
Thiago Pereira dos Santos, Universidade Federal Fluminense
Rebecca S. Robinson, University of Rhode Island
John M. Rolison, University of Otago
Margit H. Simon, Bjerknes Centre for Climate Research
Jeroen J.L. van der Lubbe, Vrije Universiteit Amsterdam
Masako Yamane, Japan Agency for Marine-Earth Science and Technology
Hucai Zhang, Yunnan Normal University

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In the southern Indian Ocean, the position of the subtropical front – the boundary between colder, fresher waters to the south and warmer, saltier waters to the north – has a strong influence on the upper ocean hydrodynamics and biogeochemistry. Here we analyse a sedimentary record from the Agulhas Plateau, located close to the modern position of the subtropical front and use alkenones and coccolith assemblages to reconstruct oceanographic conditions over the past 300,000 years. We identify a strong glacial-interglacial variability in sea surface temperature and productivity associated with subtropical front migration over the Agulhas Plateau, as well as shorter-term high frequency variability aligned with variations in high latitude insolation. Alkenone and coccolith abundances, in combination with diatom and organic carbon records indicate high glacial export productivity. We conclude that the biological pump was more efficient and strengthened during glacial periods, which could partly account for the reported reduction in atmospheric carbon dioxide concentrations.

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Communications Earth and Environment