Global reorganization of deep-sea circulation and carbon storage after the last ice age

Creators: Rafter, Patrick A.; Gray, William R.; Hines, Sophia K.V.; Burke, Andrea; Costa, Kassandra M.; Gottschalk, Julia; Hain, Mathis P.; Rae, James W.B.; Southon, John R.; Walczak, Maureen H.; Yu, Jimin; Adkins, Jess F.; DeVries, Timothy

Abstract

Using new and published marine fossil radiocarbon (¹⁴C/C) measurements, a tracer uniquely sensitive to circulation and air-sea gas exchange, we establish several benchmarks for Atlantic, Southern, and Pacific deep-sea circulation and ventilation since the last ice age. We find the most ¹⁴C-depleted water in glacial Pacific bottom depths, rather than the mid-depths as they are today, which is best explained by a slowdown in glacial deep-sea overturning in addition to a "flipped" glacial Pacific overturning configuration. These observations cannot be produced by changes in air-sea gas exchange alone, and they underscore the major role for changes in the overturning circulation for glacial deep-sea carbon storage in the vast Pacific abyss and the concomitant drawdown of atmospheric CO₂.

Additional Information

© 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY). We want to thank the authors of prior marine radiocarbon compilations by L. Skinner and N. Zhao (21, 33) as well as C. Bertrand, N. Shammas, J. Noel Deline, J. Sanchez, M. Ngo, K. Legaspi, and C. Xu for assistance in sample preparation and analyses. The manuscript benefited from comments by two anonymous reviewers as well as conversations with D. Lund, A. Mix, B. Anderson, M. Cook, C. D. Charles, and others. This work was supported by grants from the NSF (OCE-2015647 and OCE-2032340 to P.A.R.; OCE-2032343 to M.P.H.), NERC grant NE/N011716/1 to J.W.B.R., and NERC grant NE/M004619/1 to A.B. Author contributions:All authors contributed to the design and writing of the paper. W.R.G., P.A.R., and T.D. wrote the code to update the age models and match modern ocean observations to proxy locations. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper, the Supplementary Materials, and at doi:10.1594/PANGAEA.946522. The code for evaluating this dataset can be found at: 10.5281/zenodo.7112182. The authors declare that they have no competing interests.

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