Preprints
https://doi.org/10.5194/cp-2021-29
https://doi.org/10.5194/cp-2021-29

  20 Apr 2021

20 Apr 2021

Review status: this preprint is currently under review for the journal CP.

Bottom water oxygenation changes in the Southwestern Indian Ocean as an indicator for enhanced respired carbon storage since the last glacial inception

Helen Eri Amsler1,2, Lena Mareike Thöle1,2,3, Ingrid Stimac4, Walter Geibert4, Minoru Ikehara5, Gerhard Kuhn4, Oliver Esper4, and Samuel Laurent Jaccard1,2 Helen Eri Amsler et al.
  • 1Institute of Geological Sciences, University of Bern, Switzerland
  • 2Oeschger Centre for Climate Change Research, University of Bern, Switzerland
  • 3Department of Earth Sciences, Utrecht University, the Netherlands
  • 4Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
  • 5Center for Advanced Marine Core Research, Kochi University, Japan

Abstract. We present downcore records of redox-sensitive authigenic uranium (U) and manganese (Mn) concentrations based on five marine sediment cores spanning a meridional transect encompassing the Subantarctic and the Antarctic zones in the Southwest Indian Ocean covering the last glacial cycle. These records signal lower bottom water oxygenation during glacial climate intervals and generally higher oxygenation during warm periods, consistent with climate-related changes in deep ocean remineralised carbon storage. Regional changes in the export of siliceous phytoplankton to the deep-sea may have entailed a secondary influence on oxygen levels at the water-sediment interface, especially in the Subantarctic Zone. The rapid reoxygenation during the deglaciation is in line with increased ventilation and enhanced upwelling after the Last Glacial Maximum (LGM), which, in combination, conspired to transfer previously sequestered remineralised carbon to the surface ocean and the atmosphere, contributing to propel the Earth’s climate out of the last ice age. These records highlight the yet insufficiently documented role the southern Indian Ocean played in the air-sea partitioning of CO2 on glacial-interglacial timescales.

Helen Eri Amsler et al.

Status: open (until 15 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Helen Eri Amsler et al.

Helen Eri Amsler et al.

Viewed

Total article views: 355 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
272 79 4 355 1 2
  • HTML: 272
  • PDF: 79
  • XML: 4
  • Total: 355
  • BibTeX: 1
  • EndNote: 2
Views and downloads (calculated since 20 Apr 2021)
Cumulative views and downloads (calculated since 20 Apr 2021)

Viewed (geographical distribution)

Total article views: 301 (including HTML, PDF, and XML) Thereof 301 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 17 May 2021
Download
Short summary
We present sedimentary redox-sensitive trace metal records from five sediment cores retrieved from the SW Indian Ocean. These records are indicative of oxygen-depleted conditions during cold periods and enhanced oxygenation during interstadials. Our results thus suggest that deep ocean oxygenation changes were mainly controlled by ocean ventilation and that a generally more sluggish circulation contributed to sequester remineralized carbon away from the atmosphere during glacial periods.