EGU24-3561, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

AMOC thresholds in CMIP6 models: NAHosMIP

Laura Jackson1, Alastrue de Asenjo Eduardo2, Bellomo Katinka3, Danabasoglu Gokhan4, Haak Helmuth2, Hu Aixue4, Jungclaus Johann2, Lee Warren5, Meccia Virna3, Saenko Oleg5, Shao Andrew5, and Swingedouw Didier6
Laura Jackson et al.
  • 1Met Office, Exeter, UK
  • 2Max Planck Institute for Meteorology, Hamburg, Germany
  • 3Institute of Atmospheric Sciences and Climate, Turin, Italy
  • 4National Center for Atmospheric Research, Boulder, USA
  • 5CCCma, Victoria, Canada
  • 6CNRS, Bordeaux INP, France

The Atlantic meridional overturning circulation (AMOC) is an important part of our climate system, which keeps the North Atlantic relatively warm. It is predicted to weaken under climate change. The AMOC may have a threshold beyond which recovery is difficult, hence showing quasi-irreversibility (hysteresis). Although hysteresis has been seen in simple models, it has been difficult to demonstrate in comprehensive global climate models.

We present results from the North Atlantic hosing model intercomparison project, where we applied an idealised forcing of a freshwater flux over the North Atlantic in 8 CMIP6 models to explore this threshold. The AMOC weakens in all models from the freshening, but once the freshening ceases, the AMOC recovers in some models, and in others it stays in a weakened state. We will discuss mechanisms behind the different behaviour in the different models. 


How to cite: Jackson, L., Eduardo, A. D. A., Katinka, B., Gokhan, D., Helmuth, H., Aixue, H., Johann, J., Warren, L., Virna, M., Oleg, S., Andrew, S., and Didier, S.: AMOC thresholds in CMIP6 models: NAHosMIP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3561,, 2024.