Asymmetry of AMOC Hysteresis in a State-Of-The-Art Global Climate Model

René M. van Westen; Henk A. Dijkstra

doi:10.1029/2023GL106088

Asymmetry of AMOC Hysteresis in a State-Of-The-Art Global Climate Model

René M. van Westen
, Henk A. Dijkstra^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

We study hysteresis properties of the Atlantic Meridional Overturning Circulation (AMOC) under a slowly-varying North Atlantic (20°N–50°N) freshwater flux forcing in state-of-the-art global climate model (GCM), the Community Earth System Model. Results are presented of a full hysteresis simulation (4,400 model years) and show that there is a hysteresis width of about 0.4 Sv. This demonstrates that an AMOC collapse and recovery do not only occur in conceptual and idealized climate models, but also in a state-of-the-art GCM. The AMOC recovery is about a factor six faster than the AMOC collapse and this asymmetry is due to the major effect of the North Atlantic sea-ice distribution on the AMOC recovery. The results have implications for projections of possible future AMOC behavior and for explaining relatively rapid climate transitions in the geological past.

Original language	English
Article number	e2023GL106088
Journal	Geophysical Research Letters
Volume	50
Issue number	22
DOIs	https://doi.org/10.1029/2023GL106088
Publication status	Published - 28 Nov 2023

Bibliographical note

Publisher Copyright:
© 2023. The Authors.

Funding

We thank Michael Kliphuis (IMAU, UU) for performing the CESM simulation. The model simulation and the analysis of all the model output was conducted on the Dutch National Supercomputer (Snellius) within NWO-SURF project 17239. R.M.v.W. and H.A.D. are funded by the European Research Council through the ERC-AdG project TAOC (project 101055096).

Funders	Funder number
NWO-SURF	17239
European Research Council	101055096

Keywords

CESM
hysteresis
ocean circulation
sea-ice
tipping

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This output contributes to the following UN Sustainable Development Goals (SDGs)

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Geophysical Research Letters - 2023 - Westen - Asymmetry of AMOC Hysteresis in a State‐Of‐The‐Art Global Climate ModelFinal published version, 3.1 MBLicence: CC BY

Cite this

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abstract = "We study hysteresis properties of the Atlantic Meridional Overturning Circulation (AMOC) under a slowly-varying North Atlantic (20°N–50°N) freshwater flux forcing in state-of-the-art global climate model (GCM), the Community Earth System Model. Results are presented of a full hysteresis simulation (4,400 model years) and show that there is a hysteresis width of about 0.4 Sv. This demonstrates that an AMOC collapse and recovery do not only occur in conceptual and idealized climate models, but also in a state-of-the-art GCM. The AMOC recovery is about a factor six faster than the AMOC collapse and this asymmetry is due to the major effect of the North Atlantic sea-ice distribution on the AMOC recovery. The results have implications for projections of possible future AMOC behavior and for explaining relatively rapid climate transitions in the geological past.",

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N2 - We study hysteresis properties of the Atlantic Meridional Overturning Circulation (AMOC) under a slowly-varying North Atlantic (20°N–50°N) freshwater flux forcing in state-of-the-art global climate model (GCM), the Community Earth System Model. Results are presented of a full hysteresis simulation (4,400 model years) and show that there is a hysteresis width of about 0.4 Sv. This demonstrates that an AMOC collapse and recovery do not only occur in conceptual and idealized climate models, but also in a state-of-the-art GCM. The AMOC recovery is about a factor six faster than the AMOC collapse and this asymmetry is due to the major effect of the North Atlantic sea-ice distribution on the AMOC recovery. The results have implications for projections of possible future AMOC behavior and for explaining relatively rapid climate transitions in the geological past.

AB - We study hysteresis properties of the Atlantic Meridional Overturning Circulation (AMOC) under a slowly-varying North Atlantic (20°N–50°N) freshwater flux forcing in state-of-the-art global climate model (GCM), the Community Earth System Model. Results are presented of a full hysteresis simulation (4,400 model years) and show that there is a hysteresis width of about 0.4 Sv. This demonstrates that an AMOC collapse and recovery do not only occur in conceptual and idealized climate models, but also in a state-of-the-art GCM. The AMOC recovery is about a factor six faster than the AMOC collapse and this asymmetry is due to the major effect of the North Atlantic sea-ice distribution on the AMOC recovery. The results have implications for projections of possible future AMOC behavior and for explaining relatively rapid climate transitions in the geological past.

KW - CESM

KW - hysteresis

KW - ocean circulation

KW - sea-ice

KW - tipping

UR - https://www.scopus.com/pages/publications/85177238827

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Asymmetry of AMOC Hysteresis in a State-Of-The-Art Global Climate Model

Abstract

Bibliographical note

Funding

Keywords

UN SDGs

Access to Document

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