EGU25-16169, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-16169
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
The role of AMOC in controlling ocean heat uptake in idealized abrupt forcing scenarios
Chiara Ventrucci1,2, Federico Fabiano2, Paolo Davini3, Oliver Mehling4, and Katinka Bellomo5
Chiara Ventrucci et al.
  • 1University of Bologna, Department of Physics and Astronomy, Bologna, Italy (chiara.ventrucci2@unibo.it)
  • 2National Research Council, Institute of Atmospheric Sciences and Climate, Bologna, Italy (CNR-ISAC)
  • 3National Research Council, Institute of Atmospheric Sciences and Climate, Turin, Italy (CNR-ISAC)
  • 4Politecnico di Torino, Department of Environment, Land, and Infrastructure Engineering, Turin, Italy
  • 5University of Padua, Department of Geosciences, Padua, Italy

Over the past 150 years, the ocean has absorbed almost 90% of the excess heat induced by anthropogenic carbon dioxide (CO2) emissions, acting as our planet's main heat reservoir. Multiple mechanisms contribute to ocean heat uptake (OHU) and global heat storage, which redistribute heat from the surface to the deep ocean and across all basins. Nevertheless, a comprehensive picture remains unclear. Within this context, the Atlantic Meridional Overturning Circulation (AMOC) plays a key role in transferring heat to the ocean's deepest layers, with a stronger AMOC related to an increase in global OHU. However, it is difficult to quantify the importance of the AMOC from the analysis of existing simulations from the Coupled Model Intercomparison Project (CMIP), as many processes are simultaneously active. 

In this study, we use the climate model EC-Earth3 to investigate how an AMOC weakening induced by a CO2 increase would influence the heat storage inside the ocean. We compare the CMIP abrupt4xCO2 simulation with an idealized experiment with the same forcing but designed to artificially maintain the AMOC strength at preindustrial levels through a positive salinity anomaly in the North Atlantic.  

We find that a change in the AMOC strength is associated with a change in heat storage, influencing both the vertical and interbasin redistribution. Due to AMOC weakening, less heat accumulates below 750 m, especially in the Atlantic Ocean, while we observe increased heat storage in intermediate layers and further heat transfer toward the Indo-Pacific Ocean. Overall, we notice a small but significant difference between the two simulations in global heat uptake, increasing in a weaker AMOC state. We hypothesize that a reduced role for AMOC-driven OHU is compensated for by an increase in heat diffusion towards the interior at low latitudes, according to recently developed conceptual models of OHU. 

These differences could influence the surface warming pattern and regional sea level rise, with implications for long-term climate changes. 

How to cite: Ventrucci, C., Fabiano, F., Davini, P., Mehling, O., and Bellomo, K.: The role of AMOC in controlling ocean heat uptake in idealized abrupt forcing scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16169, https://doi.org/10.5194/egusphere-egu25-16169, 2025.