Japan Geoscience Union Meeting 2019

Presentation information

[J] Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS14] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

Mon. May 27, 2019 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Osamu Seki(Institute of Low Temperature Science, Hokkaido University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Ryu Uemura(University of the Ryukyus), Ryosuke Makabe(National Institute of Polar Research)

[MIS14-P11] Lithogenic fluxes across a transect in the SW Indian Ocean since the last glacial inception

*Eri Helen Amsler1, Walter Geibert2, Gerhard Kuhn2, Minoru Ikehara3, Samuel Jaccard1 (1.Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Switzerland, 2.Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany, 3.Center for Advanced Marine Core Research, Kochi University, Kochi, Japan)

Keywords:Southern Ocean, Biological Pump

On glacial-interglacial time scale the Southern Ocean plays a prominent role in modulating climate by storing and redistributing heat, fresh water, carbon and nutrients globally. Atmospheric CO2 is taken up by algae and sequestered in the deep ocean through the biological carbon pump. On the other hand, CO2 is released back to the atmosphere through upwelling and vertical mixing [1]. The relative contribution of these two mechanisms controls the efficiency through which carbon can be sequestered in the ocean interior.

The effect of iron fertilization on biological productivity has previously been documented in the Atlantic and Pacific sectors of the Southern Ocean [2, 3]. During glacial periods higher input of Fe-bearing dust increased phytoplankton growth and carbon sequestration, thus leading to the drawdown of atmospheric CO2, accounting for about half of the glacial-interglacial CO2 amplitude [4].

Here we present 230Th-normalized lithogenic fluxes in a set of marine sediment cores spanning a meridional transect in the Indian sector of the Southern Ocean further away from the Patagonian dust plume and show that increased Fe flux impacted export production patterns, contributing to the sequestration of carbon away from the atmosphere.

[1] Sigman, D. M., Boyle, E. A. (2000) Nature 407, 859-869.

[2] Martínez-Garcia, A., Sigman, D. M., Haojia, R., Anderson, R. F., Straub, M., Hodell, D. A., Jaccard, S. L., Eglinton, T. I., Haug, G. H. (2014) Science 343, 1347-1350.

[3] Lamy F., Gersonde, R., Winckler, G., Esper, O., Jaeschke, A., Kuhn, G., Ullermann, J., Martínez-Garcia, A., Lambert, F., Kilian, R. (2014) Science 343 (6169), 403-407.

[4] Hain, M. P., D. M. Sigman, and G. H. Haug (2010) Global Biogeochem. Cycles, 24, GB4023.
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