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Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3
Author(s) -
Zhu Jiang,
Liu Zhengyu,
Zhang Xu,
Eisenman Ian,
Liu Wei
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl060891
Subject(s) - geology , ice sheet , climatology , sea ice , meltwater , antarctic sea ice , ice sheet model , cryosphere , northern hemisphere , westerlies , oceanography , ice stream , north atlantic deep water , glacial period , thermohaline circulation , geomorphology
The transient response of the Atlantic Meridional Overturning Circulation (AMOC) to a deglacial ice sheet retreat is studied using the Community Climate System Model version 3 (CCSM3), with a focus on orographic effects rather than meltwater discharge. It is found that the AMOC weakens significantly (41%) in response to the deglacial ice sheet retreat. The AMOC weakening follows the decrease of the Northern Hemisphere ice sheet volume linearly, with no evidence of abrupt thresholds. A wind‐driven mechanism is proposed to explain the weakening of the AMOC: lowering the Northern Hemisphere ice sheets induces a northward shift of the westerlies, which causes a rapid eastward sea ice transport and expanded sea ice cover over the subpolar North Atlantic; this expanded sea ice insulates the ocean from heat loss and leads to suppressed deep convection and a weakened AMOC. A sea ice‐ocean positive feedback could be further established between the AMOC decrease and sea ice expansion.