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

• Published in: Geophysical Research Letters
• Main Authors: Zhu, Jiang, Liu, Zhengyu, Zhang, Xu, Eisenman, Ian, Liu, Wei
• Other Authors: Zhu, J (reprint author), Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA., Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA., Univ Wisconsin, Ctr Climat Res, Madison, WI USA., Peking Univ, Sch Phys, Lab Climate & Ocean Atmosphere Studies, Beijing 100871, Peoples R China., Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Bremerhaven, Germany., Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA.
• Format: Journal/Newspaper
• Language: English
• Published: geophysical research letters 2014
• Subjects: Atlantic Meridional Overturning Circulation; ice sheet retreat; ice sheet orography; sea ice transport; ATLANTIC THERMOHALINE CIRCULATION; GLOBAL CLIMATE-CHANGE; LAST DEGLACIATION; CARBON-DIOXIDE; AGE; SIMULATIONS; STABILITY; SURFACE; MODEL; CYCLE; Ice Sheet; North Atlantic; Sea ice
• Online Access: https://hdl.handle.net/20.500.11897/388359; https://doi.org/10.1002/2014GL060891

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. Geosciences, Multidisciplinary SCI(E) EI 0 ARTICLE [e-mail]; [e-mail] 17 6252-6258 41