Linear weakening of the AMOC in response to receding glacial ice sheets in CCSM3
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...
Published in: | Geophysical Research Letters |
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Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
eScholarship, University of California
2014
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Subjects: | |
Online Access: | https://escholarship.org/uc/item/18f047t7 https://escholarship.org/content/qt18f047t7/qt18f047t7.pdf https://doi.org/10.1002/2014gl060891 |
Summary: | 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. |
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