Lear, CH;
Billups, K;
Rickaby, REM;
Diester-Haass, L;
Mawbey, EM;
Sosdian, SM;
(2016)
Breathing more deeply: Deep ocean carbon storage during the mid-Pleistocene climate transition.
Geology
, 44
(12)
pp. 1035-1038.
10.1130/G38636.1.
Preview |
Text
1035.pdf - Published Version Download (247kB) | Preview |
Abstract
The ∼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 (δ18O, δ13C) 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 δ13C 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 pCO2. The amplitude of glacial-interglacial changes in δ13C increased across the MPT, but this was not mirrored by changes in nutrient content. We interpret this in terms of air-sea CO2 exchange effects, which changed the δ13C 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 CO2 outgassing in the Southern Ocean, providing an additional mechanism for reducing glacial atmospheric pCO2. Conversely, following the establishment of the ∼100 k.y. glacial cycles, δ13C of interglacial northern-sourced waters increased, perhaps reflecting reduced invasion of CO2 into the North Atlantic following the MPT. GeoRef Subject DSDP Site 607 carbon Deep Sea Drilling Project paleoclimatology IPOD Mid-Atlantic Ridge oxygen isotopes middle Pleistocene Pleistocene atmosphere C-13/C-12 climate change isotope ratios O-18/O-16 Atlantic Ocean Cenozoic carbonates upper Pleistocene Leg 94 North Atlantic Northeast Atlantic trace metals Quaternary stable isotopes
| Type: | Article |
|---|---|
| Title: | Breathing more deeply: Deep ocean carbon storage during the mid-Pleistocene climate transition |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1130/G38636.1 |
| Publisher version: | https://doi.org/10.1130/G38636.1 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Science & Technology, Physical Sciences, Geology, ATMOSPHERIC CO2, SOUTHERN-OCEAN, DIOXIDE CONCENTRATION, ISOTOPIC COMPOSITION, ICE, CIRCULATION, WATER, GLACIATION, GRADIENTS, EVOLUTION |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10053198 |
Archive Staff Only
 |
View Item |
