A Weakened AMOC Could Cause Southern Ocean Temperature and Sea‐Ice Change on Multidecadal Timescales

Diamond, Rachel ORCID: https://orcid.org/0009-0007-9071-139X; Sime, Louise C. ORCID: https://orcid.org/0000-0002-9093-7926; Schroeder, David ORCID: https://orcid.org/0000-0003-2351-4306; Jackson, Laura C.; Holland, Paul R. ORCID: https://orcid.org/0000-0001-8370-289X; de Asenjo, Eduardo Alastrué ORCID: https://orcid.org/0000-0002-9720-0257; Bellomo, Katinka ORCID: https://orcid.org/0000-0001-7954-4390; Danabasoglu, Gokhan ORCID: https://orcid.org/0000-0003-4676-2732; Hu, Aixue ORCID: https://orcid.org/0000-0002-1337-287X; Jungclaus, Johann ORCID: https://orcid.org/0000-0002-3849-4339; Montoya, Marisa ORCID: https://orcid.org/0000-0002-0090-4750; Meccia, Virna L. ORCID: https://orcid.org/0000-0001-6905-2747; Saenko, Oleg A. ORCID: https://orcid.org/0000-0002-7168-7159; Swingedouw, Didier ORCID: https://orcid.org/0000-0002-0583-0850. 2025 A Weakened AMOC Could Cause Southern Ocean Temperature and Sea‐Ice Change on Multidecadal Timescales. Journal of Geophysical Research: Oceans, 130 (7), e2024JC022027. 22, pp. 10.1029/2024JC022027

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Text (Open Access) © 2025. The Author(s). JGR Oceans - 2025 - Diamond - A Weakened AMOC Could Cause Southern Ocean Temperature and Sea‐Ice Change on Multidecadal.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (6MB) | Preview

Abstract/Summary

We present the first CMIP6-era multi-model intercomparison of the Southern Ocean (SO) temperature and sea-ice response to substantial Atlantic meridional overturning circulation (AMOC) weakening. Results are based on analysis of the North Atlantic Hosing Model Intercomparison Project, involving eight CMIP6 models under identical North Atlantic freshwater hosing. On multidecadal timescales, we find that southwards ocean heat transport into the SO increases, causing surface warming and sea-ice loss. Additionally, an atmospheric tropical-Antarctic teleconnection, identified here for the first time, causes regional temperature and sea-ice changes in the SO. Unlike previous studies, we find that the Amundsen Sea Low deepens for only some models. Overall, in the multi-model ensemble mean (multi-model range in brackets), over years 50–100 after AMOC weakening: SO surface air temperature warms by 0.3 (0.1–0.7)°C, sea level pressure (SLP) decreases by 30 (10–70) Pa, and sea-ice area decreases by 0.4 (−0.2–1.3) Mkm2. The teleconnection leads to regional differences between the response in the Indian sector and the Weddell Sea of 180 (80–320) Pa in SLP, 0.6 (0.5–1.4)°C in surface air temperature, and 0.1 (0.1–0.2) Mkm2 in sea-ice area. These SO heat transport, temperature, pressure, and sea-ice changes are small relative to the changes expected under future anthropogenic warming, despite the large and idealized 0.3 Sv hosing used to weaken the AMOC.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2024JC022027
ISSN:	2169-9275
Additional Keywords:	AMOC, southern ocean, sea ice, climate models, CMIP6
Date made live:	02 Jul 2025 11:03 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539747

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