Coherent deglacial changes in western Atlantic Ocean circulation

Abrupt climate changes in the past have been attributed to variations in Atlantic Meridional Overturning Circulation (AMOC) strength. However, the exact timing and magnitude of past AMOC shifts remain elusive, which continues to limit our understanding of the driving mechanisms of such climate varia...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Ng, Hong Chin, Robinson, Laura F., McManus, Jerry F., Mohamed, Kais J., Jacobel, Allison W., Ivanovic, Ruza F., Gregoire, Lauren J., Chen, Tianyu
Format: Text
Language:English
Published: Nature Publishing Group UK 2018
Subjects:
Article
Ice Sheet
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6063924/
http://www.ncbi.nlm.nih.gov/pubmed/30054472
https://doi.org/10.1038/s41467-018-05312-3
Description
Summary:Abrupt climate changes in the past have been attributed to variations in Atlantic Meridional Overturning Circulation (AMOC) strength. However, the exact timing and magnitude of past AMOC shifts remain elusive, which continues to limit our understanding of the driving mechanisms of such climate variability. Here we show a consistent signal of the 231Pa/230Th proxy that reveals a spatially coherent picture of western Atlantic circulation changes over the last deglaciation, during abrupt millennial-scale climate transitions. At the onset of deglaciation, we observe an early slowdown of circulation in the western Atlantic from around 19 to 16.5 thousand years ago (ka), consistent with the timing of accelerated Eurasian ice melting. The subsequent weakened AMOC state persists for over a millennium (~16.5–15 ka), during which time there is substantial ice rafting from the Laurentide ice sheet. This timing indicates a role for melting ice in driving a two-step AMOC slowdown, with a positive feedback sustaining continued iceberg calving and climate change during Heinrich Stadial 1.

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