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Breathing more deeply; deep ocean carbon storage during the mid-Pleistocene climate transition

Caroline H. Lear, Katharina Billups, Rosalind E. M. Rickaby, Liselotte Diester-Haass, Elaine M. Mawbey and Sindia M. Sosdian
Breathing more deeply; deep ocean carbon storage during the mid-Pleistocene climate transition
Geology (Boulder) (October 2016) 44 (12): 1035-1038


The approximately 100 k.y. cyclicity of the late Pleistocene ice ages started during the mid-Pleistocene transition (MPT), as ice sheets became larger and persisted for longer. The climate system feedbacks responsible for introducing this nonlinear ice sheet response to orbital variations in insolation remain uncertain. Here we present benthic foraminiferal stable isotope (delta (super 18) O, delta (super 13) C) and trace metal records (Cd/Ca, B/Ca, U/Ca) from Deep Sea Drilling Project Site 607 in the North Atlantic. During the onset of the MPT, glacial-interglacial changes in delta (super 13) C values are associated with changes in nutrient content and carbonate saturation state, consistent with a change in water mass at our site from a nutrient-poor northern source during interglacial intervals to a nutrient-rich, corrosive southern source during glacial intervals. The respired carbon content of glacial Atlantic deep water increased across the MPT. Increased dominance of corrosive bottom waters during glacial intervals would have raised mean ocean alkalinity and lowered atmospheric pCO (sub 2) The amplitude of glacial-interglacial changes in delta (super 13) C increased across the MPT, but this was not mirrored by changes in nutrient content. We interpret this in terms of air-sea CO (sub 2) exchange effects, which changed the delta (super 13) C signature of dissolved inorganic carbon in the deep water mass source regions. Increased sea ice cover or ocean stratification during glacial times may have reduced CO (sub 2) outgassing in the Southern Ocean, providing an additional mechanism for reducing glacial atmospheric pCO (sub 2) Conversely, following the establishment of the approximately 100 k.y. glacial cycles, delta (super 13) C of interglacial northern-sourced waters increased, perhaps reflecting reduced invasion of CO (sub 2) into the North Atlantic following the MPT.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 12
Title: Breathing more deeply; deep ocean carbon storage during the mid-Pleistocene climate transition
Affiliation: Cardiff University, School of Earth and Ocean Sciences, Cardiff, United Kingdom
Pages: 1035-1038
Published: 20161020
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 31
Accession Number: 2017-002992
Categories: Quaternary geologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Data Repository item 2016346
Illustration Description: illus.
N41°00'04" - N41°00'05", W32°57'27" - W32°57'26"
Secondary Affiliation: University of Delaware, USA, United StatesUniversity of Oxford, GBR, United KingdomUniversitaet des Saarlandes, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201703
Program Name: DSDPDeep Sea Drilling Project
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