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Title: Unstable AMOC during glacial intervals and millennial variability: The role of mean sea ice extent

A striking feature of paleoclimate records is the greater stability of the Holocene epoch relative to the preceding glacial interval, especially apparent in the North Atlantic region. In particular, strong irregular variability with an approximately 1500 yr period, known as the Dansgaard-Oeschger (D-O) events, punctuates the last glaciation, but is absent during the interglacial. Prevailing theories, modeling and data suggest that these events, seen as abrupt warming episodes in Greenland ice cores and sea surface temperature records in the North Atlantic, are linked to reorganizations of the Atlantic Meridional Overturning Circulation (AMOC). In this study, using a new low-order ocean model that reproduces a realistic power spectrum of millennial variability, we explore differences in the AMOC stability between glacial and interglacial intervals of the 100 kyr glacial cycle of the Late Pleistocene (1 kyr = 1000 yr). Previous modeling studies show that the edge of sea ice in the North Atlantic shifts southward during glacial intervals, moving the region of the North Atlantic Deep Water formation and the AMOC also southward. Finally, here we demonstrate that, by shifting the AMOC with respect to the mean atmospheric precipitation field, such a displacement makes the system unstable, which explains chaotic millennial variabilitymore » during the glacials and the persistence of stable ocean conditions during the interglacials.« less
 [1] ;  [2]
  1. Univ. of Southampton (United Kingdom). Ocean and Earth Science, National Oceanography Centre Southampton
  2. Yale Univ., New Haven, CT (United States). Dept. of Geology and Geophysics
Publication Date:
Grant/Contract Number:
SC0007037; AGS-1405272
Published Article
Journal Name:
Earth and Planetary Science Letters
Additional Journal Information:
Journal Volume: 429; Journal Issue: C; Journal ID: ISSN 0012-821X
Research Org:
Univ. of Southampton (United Kingdom). Ocean and Earth Science, National Oceanography Centre Southampton
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; Atlantic meridional overturning circulation; Holocene climate stability; Dansgaard–Oeschger events; millennial climate variability; glacial–interglacial cycle
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1437176