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Impacts of the North Atlantic Gyre circulation on Holocene climate off northwest Africa

Jung-Hyun Kim, Helge Meggers, Norel Rimbu, Gerrit Lohmann, Tim Freudenthal, Peter J. Mueller and Ralph R. Schneider
Impacts of the North Atlantic Gyre circulation on Holocene climate off northwest Africa
Geology (Boulder) (May 2007) 35 (5): 387-390

Abstract

We present well-dated high-resolution Holocene records of sea-surface temperature (SST) and upwelling intensity off northwest (NW) Africa. We identify long-term cooling trends over the Holocene in the subtropical North Atlantic in response to boreal summer insolation. A pronounced cooling event of approximately 1 degrees C ca. 8.5 cal ka indicates a large-scale reorganization of the ocean current system possibly induced by melt-water from the northern North Atlantic. Our alkenone SST record off Cape Ghir provides strong evidence for the impact of ocean circulation changes on subtropical North Atlantic SSTs. It is likely that cold waters were propagated to the subtropics via the Canary Current in a way similar to Heinrich events and the Younger Dryas off Cape Blanc. We find 2-3 k.y. periodic variations in SST and upwelling intensity off NW Africa superimposed on the cooling trend. Such a cycle has been documented in various paleoclimate archives in phase with solar forcing. We show that these variations on millennial time scales are linked to the North Atlantic subtropical gyre circulation and the Northern Hemisphere atmospheric circulation, and in particular to changes in the pressure gradient between the Icelandic Low and the Azores High. This suggests that oceanic circulation, in response to solar forcing, played a more important role in the generation of 2-3 k.y. cyclicity than has been previously considered.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 35
Serial Issue: 5
Title: Impacts of the North Atlantic Gyre circulation on Holocene climate off northwest Africa
Affiliation: Universitaet Bremen, FB Geowissenschaften, Bremen, Federal Republic of Germany
Pages: 387-390
Published: 200705
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2007-045046
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2007094
Illustration Description: illus. incl. sketch maps
S35°00'00" - N37°00'00", W18°00'00" - E51°00'00"
N00°00'00" - N75°00'00", W80°00'00" - E20°00'00"
Secondary Affiliation: Alfred Wegener Institute for Polar and Marine Research, DEU, Federal Republic of GermanyChristian-Albrechts-Universitaet zu Kiel, DEU, Federal Republic of Germany
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: 200724
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