Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 7 (2014):144–150, doi:10.1038/ngeo2045.
Description:
Heinrich events - surges of icebergs into the North Atlantic Ocean - punctuated the last
glacial period. The events are associated with millennial-scale cooling in the Northern
Hemisphere. Freshwater from the melting icebergs is thought to have interrupted the
Atlantic meridional overturning circulation, thus minimizing heat transport into the
northern North Atlantic. The northward flow of warm water passes through the Florida
Straits and is reflected in the distribution of seawater properties in this region. Here we
investigate the northward flow through this region over the past 40,000 years using oxygen
isotope measurements of benthic foraminifera from two cores on either side of the Florida
Straits, which allow us to estimate water density, which is related to flow via the thermal
wind relation. We infer a substantial reduction of flow during Heinrich Event 1 and the
Heinrich-like Younger Dryas cooling, but little change during Heinrich Events 2 and 3,
which occurred during an especially cold phase of the last glacial period. We speculate that
because glacial circulation was already weakened before the onset of Heinrich Events 2 and
3, freshwater forcing had little additional effect. However, low-latitude climate
perturbations were observed during all events. We therefore suggest these perturbations
may not have been directly caused by changes in heat transport associated with Atlantic
overturning circulation as commonly assumed.
Description:
The authors acknowledge the US National Science Foundation (OCE-0096472, OCE-0648258
and OCE-1102743), a grant from the Comer Science and Education Foundation and a Rutt
Bridges Undergraduate Research Fellowship to L.G.H. for funding this work. PC acknowledges
the supports from the Natural Science Foundation of China (40921004 and 40930844). S.M. was
funded through the DFG Research Center/Cluster of Excellence “The Ocean in the Earth
System”.
Description:
2014-07-12
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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