Evaluating the glacial-deglacial carbon respiration and ventilation change hypothesis as a mechanism for changing atmospheric CO2

Type Article
Date 2021-02
Language English
Author(s) Stott Lowell D1, Shao Jun1, Yu Jimin2, Harazin Kathleen M2
Affiliation(s) 1 : Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA 90089, USA
2 : Research School of Earth Sciences, The Australian National University, Canberra, ACT 2601, Australia
Source Geophysical Research Letters ( GRL ) (0094-8276) (American Geophysical Union), 2021-02 , Vol. 48 , N. 3 , P. e2020GL091296 (9p.)
DOI 10.1029/2020GL091296
Note This article also appears in: Understanding Carbon-Climate Feedbacks
Keyword(s) carbon isotope proxies, carbon respiration hypothesis, deep water ventilation, glacial pCO2

The prevailing hypothesis to explain pCO2 rise at the last glacial termination calls upon enhanced ventilation of excess respired carbon that accumulated in the deep sea during the glacial. Recent studies argue lower [O2] in the glacial ocean is indicative of increased carbon respiration. The magnitude of [O2] depletion was 100–140 µ mol/kg at the glacial maximum. Because respiration is coupled to δ13C of dissolved inorganic carbon (DIC), [O2] depletion of 100–140 µ mol/kg from carbon respiration would lower deep water δ13CDIC by ∼1‰ relative to surface water. Prolonged sequestration of respired carbon would also lower the amount of 14C in the deep sea. We show that Pacific Deep Water δ13CDIC did not decrease relative to the surface ocean and Δ14C was only ∼50‰ lower during the late glacial. Model simulations of the hypothesized ventilation change during deglaciation lead to large increases in δ13CDIC, Δ14C, and ε14C that are not recorded in observations.

Plain Language Summary

The prevailing hypothesis to explain atmospheric CO2 variability during glacial/interglacial cycles assumes atmospheric CO2 was sequestered into the deep sea as respired metabolic carbon. Recent studies argue in support of this by suggesting lower oxygen concentrations in the deep Pacific during the glacial reflects increased oxidation of marine organic matter that promoted a larger accumulation of respired carbon. We show this interpretation is not validated by independent tests, including records of deep water δ13C and Δ14C.

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Publisher's official version 23 1 MB Open access
Supporting Information S1 1 MB Open access
Figure S1 4 MB Open access
Figure S2 768 KB Open access
Preprint 10.1002/essoar.10504708.1 23 2 MB Open access
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How to cite 

Stott Lowell D, Shao Jun, Yu Jimin, Harazin Kathleen M (2021). Evaluating the glacial-deglacial carbon respiration and ventilation change hypothesis as a mechanism for changing atmospheric CO2. Geophysical Research Letters ( GRL ), 48(3), e2020GL091296 (9p.). Publisher's official version : https://doi.org/10.1029/2020GL091296 , Open Access version : https://archimer.ifremer.fr/doc/00682/79437/