Weak overturning circulation and high Southern Ocean nutrient utilization maximized glacial ocean carbon

Muglia, Juan and Skinner, Luke C. and Schmittner, Andreas (2018) Weak overturning circulation and high Southern Ocean nutrient utilization maximized glacial ocean carbon. Earth and Planetary Science Letters, 496. pp. 47-56. ISSN 0012821X DOI https://doi.org/10.1016/j.epsl.2018.05.038

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Official URL: https://doi.org/10.1016/j.epsl.2018.05.038

Abstract

Circulation changes have been suggested to play an important role in the sequestration of atmospheric CO2 in the glacial ocean. However, previous studies have resulted in contradictory results regarding the strength of the Atlantic Meridional Overturning Circulation (AMOC) and three-dimensional, quantitative reconstructions of the glacial ocean constrained by multiple proxies remain scarce. Here we simulate the modern and glacial ocean using a coupled physical-biogeochemical, global, three-dimensional model constrained simultaneously by C, radiocarbon, and N to explore the effects of AMOC differences and Southern Ocean iron fertilization on the distributions of these isotopes and ocean carbon storage. We show that C and radiocarbon data sparsely sampled at the locations of existing glacial sediment cores can be used to reconstruct the modern AMOC accurately. Applying this method to the glacial ocean we find that a surprisingly weak (6–9 Sv or about half of today's) and shallow AMOC maximizes carbon storage and best reproduces the sediment isotope data. Increasing the atmospheric soluble iron flux in the model's Southern Ocean intensifies export production, carbon storage, and further improves agreement with C and N reconstructions. Our best fitting simulation is a significant improvement compared with previous studies, and suggests that both circulation and export production changes were necessary to maximize carbon storage in the glacial ocean.

Item Type: Article
Uncontrolled Keywords: 2018AREP, IA73
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 496
Page Range: pp. 47-56
Identification Number: https://doi.org/10.1016/j.epsl.2018.05.038
Depositing User: Sarah Humbert
Date Deposited: 16 Nov 2018 10:58
Last Modified: 16 Nov 2018 10:58
URI: http://eprints.esc.cam.ac.uk/id/eprint/4341

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