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Eastern North American freshwater discharge during the Bolling-Allerod warm periods

Elizabeth A. Obbink, Anders E. Carlson and Gary P. Klinkhammer
Eastern North American freshwater discharge during the Bolling-Allerod warm periods
Geology (Boulder) (February 2010) 38 (2): 171-174


During the last deglaciation (ca. 19-6.5 ka), increased freshwater discharge to the North Atlantic likely caused reductions in Atlantic meridional overturning circulation (AMOC) strength. However, the locations and rates of freshwater discharge are not well constrained, particularly those during the centennial-scale climate oscillations of the Bolling-Allerod warm periods (ca. 14.6-12.9 ka). Here we reconstruct the salinity-dependent delta (super 18) O (sub sw) (sw, seawater) adjacent to the eastern outlets of North America, using paired Mg/Ca and delta (super 18) O records on planktonic foraminifera, to investigate whether increased discharge to the North Atlantic caused reductions in AMOC during the Bolling-Allerod and earlier periods of deglaciation. In general, delta (super 18) O (sub sw) decreased and inferred freshwater discharge increased during periods of reduced AMOC. During the Bolling-Allerod, delta (super 18) O (sub sw) decreases coincided with three reductions in AMOC strength ca. 14.1, 13.8, and 13.3 ka. Freshwater discharge modeling suggests that discharge increases of 0.03-0.05 Sverdrups (10 (super 6) m (super 3) s (super -1) ) would explain these delta (super 18) O (sub sw) decreases, which were sufficient to force reductions in AMOC strength. Concurrent changes in North Atlantic temperature, and subtropical and tropical atmospheric circulation and precipitation imply that small variations in the North Atlantic hydrologic system may have significant impacts on Northern Hemisphere climate.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 38
Serial Issue: 2
Title: Eastern North American freshwater discharge during the Bolling-Allerod warm periods
Affiliation: University of Wisconsin, Department of Geoscience, Madison, WI, United States
Pages: 171-174
Published: 201002
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2010-024677
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010034
Illustration Description: illus. incl. sketch map
N00°00'00" - N75°00'00", W80°00'00" - E20°00'00"
Secondary Affiliation: Oregon State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201015
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