The Atlantic Meridional Overturning Circulation: Exploring sensitivity to model resolution using ARCHER 2

The Atlantic Meridional Overturning Circulation (AMOC) is an important ocean current that transports warm water poleward, maintaining the temperate climate of the North Atlantic. However, as rising greenhouse gas concentrations warm the climate, the AMOC is projected to weaken. This reduction in heat transport may have profound consequences, including colder winters and disrupted global rainfall patterns.

Despite this, the exact mechanism and magnitude of this weakening remain poorly understood. Additionally, standard climate models have a comparatively coarse spatial resolution that fails to capture the observed structure of  ocean currents of the northern Atlantic. Modelling studies suggest that the AMOC’s sensitivity is highly dependent on how well these features are resolved. To accurately simulate these processes and bridge the gap between models and reality, high-performance computing (HPC) platforms like ARCHER2 are necessary for the high-resolution, long-term simulations required.

We present two sets of experiments using both standard and high resolution versions of  the HadGEM3-GC3.1 climate model to explore how the AMOC responds to a changing climate: i)  CO2 Quadrupling simulations to examine the potential for a rapid AMOC collapse and  ii) simulations examining how the atmosphere variability (the North Atlantic Oscillation - NAO) on drives long-term variations in the AMOC.