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...
Published in: | Nature Communications |
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Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Nature Publishing Group
2018
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Subjects: | |
Online Access: | https://archimer.ifremer.fr/doc/00495/60698/65409.pdf https://archimer.ifremer.fr/doc/00495/60698/65410.pdf https://archimer.ifremer.fr/doc/00495/60698/65411.pdf https://archimer.ifremer.fr/doc/00495/60698/65412.xlsx https://archimer.ifremer.fr/doc/00495/60698/65413.xlsx https://archimer.ifremer.fr/doc/00495/60698/65414.xlsx https://doi.org/10.1038/s41467-018-05312-3 https://archimer.ifremer.fr/doc/00495/60698/ |
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 Pa-231/Th-230 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 (similar to 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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