231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

• Published in: Nature communications Vol. 5; no. 1; p. 5817
• Main Authors: Bradtmiller, Louisa I., McManus, Jerry F., Robinson, Laura F.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18-12-2014; Nature Publishing Group
• Subjects: 704/106/413; 704/106/829/2737; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723
• DOI: 10.1038/ncomms6817

The strength of Atlantic meridional overturning circulation is believed to affect the climate over glacial-interglacial and millennial timescales. The marine sedimentary
231
Pa/
230
Th ratio is a promising paleocirculation proxy, but local particle effects may bias individual reconstructions. Here we present new Atlantic sedimentary
231
Pa/
230
Th data from the Holocene, the last glacial maximum and Heinrich Stadial 1, a period of abrupt cooling ca. 17,500 years ago. We combine our results with published data from these intervals to create a spatially distributed sedimentary
231
Pa/
230
Th database. The data reveal a net
231
Pa deficit during each period, consistent with persistent
231
Pa export. In highly resolved cores, Heinrich
231
Pa/
230
Th ratios exceed glacial ratios at nearly all depths, indicating a significant reduction, although not cessation, of overturning during Heinrich Stadial 1. These results support the inference that weakened overturning was a driver of Heinrich cooling, while suggesting that abrupt climate oscillations do not necessarily require a complete shutdown of overturning.
Marine sedimentary
231
Pa/
230
Th ratios are considered a promising tool for the investigation of past modes of ocean circulation. Here, the authors present a compilation of new and existing Atlantic sedimentary
231
Pa/
230
Th ratios and interpret these data in the context of abrupt cooling during Heinrich Stadial 1.