Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation

• Published in: Geology
• Main Authors: Carlson, Anders E., Oppo, Delia W., Came, Rosemarie E., LeGrande, Allegra N., Keigwin, Lloyd D., Curry, William B.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Geological Society of America 2008
• Subjects: North Atlantic
• Online Access: https://doi.org/10.1130/G25080A.1

During the last deglaciation (ca. 21–10 ka), freshening of the North Atlantic surface likely caused reductions in Atlantic meridional overturning circulation (AMOC); the mechanisms related to AMOC recovery remain poorly understood. Here we present three new deglacial surface temperature and δ18Oseawater (δ18Osw) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic δ18Osw records suggest that a salty surface water mass accumulated in the western Atlantic from 27°S to 33°N during periods of reduced AMOC. However, δ18Osw decreases led deep AMOC resumption by hundreds of years. We suggest that the northward export of salt previously trapped in the western Atlantic resulted in the early establishment of a shallow overturning circulation that eventually culminated in deep AMOC resumption, implying that AMOC may constitute a self-limiting system. Copyright © 2008 by the Geological Society of America. Manuscript received 23 April 2008. Revised manuscript received 19 August 2008. Manuscript accepted 3 September 2008. We thank L. Zou, S. Brown-Leger, M. Carman, S. Birdwhistell, and D. Ostermann for technical assistance; H. Benway, S. Desprat, S. Marcott, J. McManus, and P. Clark for discussion of ideas; M. Conte, P. Anand, and L. Skinner for sharing samples and data; the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) for radiocarbon dates; and the Woods Hole Oceanographic Institution (WHOI) inductively coupled plasma–mass spectrometry laboratory and core repository. Comments by six anonymous reviewers greatly improved this manuscript. Research was funded by a WHOI Postdoctoral Scholarship (Carlson), the WHOI Ocean Climate Change Institute (Oppo, Came), and the National Science Foundation (Oppo, Keigwin, Curry). GSA Data Repository item 2008246, detailed methods and results description, core data, and additional tables and figures, is available online at www.geosociety.org/pubs/ft2008.htm, or on request from ...