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 |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Wiley
2014
|
Subjects: | |
Online Access: | https://epic.awi.de/id/eprint/36169/ https://epic.awi.de/id/eprint/36169/1/2014gl060891.pdf http://onlinelibrary.wiley.com/enhanced/doi/10.1002/2014GL060891/ https://hdl.handle.net/10013/epic.44204 https://hdl.handle.net/10013/epic.44204.d001 |
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. |
---|