Holocene evolution of the North Atlantic subsurface transport

Type Article
Date 2017-04
Language English
Author(s) Repschlaeger Janne1, Garbe-Schoenberg Dieter1, Weinelt Mara2, Schneider RalphORCID1
Affiliation(s) 1 : Univ Kiel, Inst Geosci, D-24118 Kiel, Germany.
2 : Univ Kiel, Inst Prehist & Protohist Archaeol, D-24118 Kiel, Germany.
Source Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2017-04 , Vol. 13 , N. 4 , P. 333-344
DOI 10.5194/cp-13-333-2017
WOS© Times Cited 19
Abstract

Previous studies suggested that short-term freshening events in the subpolar gyre can be counterbalanced by advection of saline waters from the subtropical gyre and thus stabilize the Atlantic Meridional Overturning Circulation (AMOC). However, little is known about the inter-gyre transport pathways. Here, we infer changes in surface and subsurface transport between the subtropical and polar North Atlantic during the last 11 000 years, by combining new temperature and salinity reconstructions obtained from combined delta O-18 and Mg/Ca measurements on surface and subsurface dwelling foraminifera with published foraminiferal abundance data from the subtropical North Atlantic, and with salinity and temperature data from the tropical and subpolar North Atlantic. This compilation implies an overall stable subtropical warm surface water transport since 10 ka BP. In contrast, subsurface warm water transport started at about 8 ka but still with subsurface heat storage in the subtropical gyre. The full strength of intergyre exchange was probably reached only after the onset of northward transport of warm saline subsurface waters at about 7 ka BP, associated with the onset of the modern AMOC mode. A critical evaluation of different potential forcing mechanisms leads to the assumption that freshwater supply from the Laurentide Ice Sheet was the main control on subtropical to subpolar ocean transport at surface and subsurface levels.

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