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Southern Ocean biogenic blooms freezing-in Oligocene colder climates


Hochmuth, K and Whittaker, JM and Sauermilch, I and Klocker, A and Gohl, K and LaCasce, JH, Southern Ocean biogenic blooms freezing-in Oligocene colder climates, Nature Communications, 13, (1) Article 6785. ISSN 2041-1723 (2022) [Refereed Article]

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Copyright Statement

2022 The Author(s). Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,(CC BY 4.0)

DOI: doi:10.1038/s41467-022-34623-9


Crossing a key atmospheric CO2 threshold triggered a fundamental global climate reorganisation ~34 million years ago (Ma) establishing permanent Antarctic ice sheets. Curiously, a more dramatic CO2 decline (~800-400 ppm by the Early Oligocene(~27 Ma)), postdates initial ice sheet expansion but the mechanisms driving this later, rapid drop in atmospheric carbon during the early Oligocene remains elusive and controversial. Here we use marine seismic reflection and borehole data to reveal an unprecedented accumulation of early Oligocene strata (up to 2.2 km thick over 1500x500 km) with a major biogenic component in the Australian Southern Ocean. High-resolution ocean simulations demonstrate that a tectonically-driven, one-off reorganisation of ocean currents, caused a unique period where current instability coincided with high nutrient input from the Antarctic continent. This unrepeated and short-lived environment favoured extreme bioproductivity and enhanced sediment burial. The size and rapid accumulation of this sediment package potentially holds ~1.067x1015 kg of the 'missing carbon' sequestered during the decline from an Eocene high CO2-world to a mid-Oligocene medium CO2-world, highlighting the exceptional role of the Southern Ocean in modulating long-term climate.

Item Details

Item Type:Refereed Article
Keywords:Southern Ocean, Oligocene, Tasmanian gateway, bioproductivity
Research Division:Earth Sciences
Research Group:Geophysics
Research Field:Seismology and seismic exploration
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Hochmuth, K (Dr Katharina Hochmuth)
UTAS Author:Whittaker, JM (Associate Professor Jo Whittaker)
ID Code:154438
Year Published:2022
Deposited By:Oceans and Cryosphere
Deposited On:2022-11-30
Last Modified:2022-12-15
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