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Atlantic Ocean circulation changes preceded millennial tropical South America rainfall events during the last glacial
Author(s) -
Burckel Pierre,
Waelbroeck Claire,
Gherardi Jeanne Marie,
Pichat Sylvain,
Arz Helge,
Lippold Joerg,
Dokken Trond,
Thil François
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062512
Subject(s) - stadial , glacial period , geology , climatology , precipitation , oceanography , shutdown of thermohaline circulation , tropical atlantic , thermohaline circulation , north atlantic deep water , sea surface temperature , holocene , geography , meteorology , paleontology
Abstract During the last glacial period, Greenland's climate shifted between cold (stadial) and warm (interstadial) phases that were accompanied by ocean circulation changes characterized by reduced Atlantic Meridional Overturning Circulation (AMOC) during stadials. Here we present new data from the western tropical Atlantic demonstrating that AMOC slowdowns preceded some of the large South American rainfall events that took place during stadials. Based on 231 Pa/ 230 Th and Ti/Ca measurements in the same sediment core, we determine that the AMOC started to slowdown 1420 ± 250 and 690 ± 180 (1 σ ) years before the onset of two large precipitation events associated with Heinrich stadials. Our results bring unprecedented evidence that AMOC changes could be at the origin of the large precipitation events observed in tropical South America during Heinrich stadials. In addition, we propose a mechanism explaining the differences in the extent and timing of AMOC slowdowns associated with shorter and longer stadials.