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Ice sheet decline and rising atmospheric CO2 control AMOC sensitivity to deglacial meltwater discharge

Sun, Yuchen, Knorr, Gregor, Zhang, Xu, Tarasov, Lev, Barker, Stephen ORCID: https://orcid.org/0000-0001-7870-6431, Werner, Martin and Lohmann, Gerrit 2022. Ice sheet decline and rising atmospheric CO2 control AMOC sensitivity to deglacial meltwater discharge. Global and Planetary Change 210 , 103755. 10.1016/j.gloplacha.2022.103755

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Abstract

The last deglaciation was characterized by a sequence of abrupt climate events thought to be linked to rapid changes in Atlantic meridional overturning circulation (AMOC). The sequence includes a weakening of the AMOC after the Last Glacial Maximum (LGM) during Heinrich Stadial 1 (HS1), which ends with an abrupt AMOC amplification at the transition to the Bølling/Allerød (B/A). This transition occurs despite persistent deglacial meltwater fluxes that counteract vigorous North Atlantic deep-water formation. Using the Earth system model COSMOS with a range of deglacial boundary conditions and reconstructed deglacial meltwater fluxes, we show that deglacial CO2 rise and ice sheet decline modulate the sensitivity of the AMOC to these fluxes. While declining ice sheets increase the sensitivity, increasing atmospheric CO2 levels tend to counteract this effect. Therefore, the occurrence of a weaker HS1 AMOC and an abrupt AMOC increase in the presence of meltwater, might be explained by these effects, as an alternative to or in combination with changes in the magnitude or routing of meltwater discharge.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Additional Information: This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Publisher: Elsevier
ISSN: 0921-8181
Date of First Compliant Deposit: 23 February 2022
Date of Acceptance: 29 January 2022
Last Modified: 17 May 2023 14:13
URI: https://orca.cardiff.ac.uk/id/eprint/147752

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