Northern-sourced water dominated the Atlantic Ocean during the Last Glacial Maximum

Pöppelmeier, F.; Blaser, P.; Gutjahr, M.; Jaccard, S. L.; Frank, M.; Max, L.; Lippold, J. (2020). Northern-sourced water dominated the Atlantic Ocean during the Last Glacial Maximum. Geology, 48(8), pp. 826-829. Geological Society of America 10.1130/G47628.1

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Increased carbon sequestration in the ocean subsurface is commonly assumed to have been one of the main causes responsible for lower glacial atmospheric CO2 concentrations. Remineralized carbon must have been stored away from the atmosphere for thousands of years, yet the water mass structure accommodating such increased carbon storage continues to be debated. Here, we present new sediment-derived bottom-water neodymium isotope records that allow fingerprinting of water masses and provide a more complete picture of the Atlantic Meridional Overturning Circulation geometry during the Last Glacial Maximum. These results suggest that the vertical and meridional structure of the Atlantic water mass distribution only experienced minor changes since the last ice age. In particular, we find no compelling evidence supporting glacial southern-sourced water substantially expanding to shallower depths and farther into the Northern Hemisphere than today, which had been previously inferred from stable carbon isotope (δ13C) reconstructions. We argue that depleted δ13C values observed in the deep Northwest Atlantic do not necessarily indicate the presence of southern-sourced water. Instead, these values may represent a northern-sourced water mass with lower than modern preformed δ13C values that were further modified downstream by increased sequestration of remineralized carbon, facilitated by a more sluggish glacial deep circulation, corroborating previous evidence.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Jaccard, Samuel

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0091-7613

Publisher:

Geological Society of America

Language:

English

Submitter:

Samuel Jaccard

Date Deposited:

28 Jul 2020 08:09

Last Modified:

06 Aug 2020 08:43

Publisher DOI:

10.1130/G47628.1

BORIS DOI:

10.7892/boris.145414

URI:

https://boris.unibe.ch/id/eprint/145414

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