Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3

Jiang Zhu; Zhengyu Liu; Xu Zhang; Ian Eisenman; Wei Liu

doi:10.1002/2014GL060891

Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3

Jiang Zhu, Zhengyu Liu, Xu Zhang, Ian Eisenman, Wei Liu

Paleo and Polar Climate

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61 Scopus citations

Abstract

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.

Original language	English
Pages (from-to)	6252-6258
Number of pages	7
Journal	Geophysical Research Letters
Volume	41
Issue number	17
DOIs	https://doi.org/10.1002/2014GL060891
State	Published - Sep 16 2014

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title = "Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3",

abstract = "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.",

author = "Jiang Zhu and Zhengyu Liu and Xu Zhang and Ian Eisenman and Wei Liu",

note = "Publisher Copyright: {\textcopyright} 2014. American Geophysical Union.",

year = "2014",

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T1 - Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3

AU - Zhu, Jiang

AU - Liu, Zhengyu

AU - Zhang, Xu

AU - Eisenman, Ian

AU - Liu, Wei

PY - 2014/9/16

Y1 - 2014/9/16

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/84907919455

U2 - 10.1002/2014GL060891

DO - 10.1002/2014GL060891

M3 - Article

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SN - 0094-8276

VL - 41

SP - 6252

EP - 6258

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 17

ER -

Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3

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