A hierarchy of high-resolution IFS-NEMO configurations for analysing climate variability and change

A suite of high-resolution configurations of the coupled climate model IFS-NEMO to investigate recent and future climate variability and change has been recently developed within the project EERIE (European Eddy-Rich Earth System Models) and the Destination Earth initiative. This contribution emphasises the climate responses emerging from these simulations and their sensitivity to spatial resolution and the experimental protocol considered.

The model hierarchy combines eddy-permitting (∼25 km) and eddy-rich (∼9 km) ocean components with convection-parameterised (∼25 km) and convection-permitting (∼4.5 km) atmospheric configurations, enabling a systematic assessment of resolution-dependent processes and feedbacks. Particular attention is given to how differences in model physics, resolution-aware tuning strategies, scenario forcing (i.e. SSP1-2.6 vs SSP3-7.0) and experimental design influence the simulated climate variability across configurations.

Ongoing analyses of historical simulations show enhanced performance for the higher-resolution configurations in the representation of mean-state properties, with especially clear improvements in dynamical fields. We further assess the extent to which the shorter spinup approach employed in Destination Earth, compared to EERIE, can reliably capture internal variability and externally forced responses while substantially reducing computational cost.

A systematically stronger future response of the Atlantic Meridional Overturning Circulation to external forcings is found in the eddy-resolving configurations compared to the eddy-permitting ones. Idealised control simulations with quadrupled CO2 forcing – inspired by the CMIP6 DECK experiments – also show a more pronounced temperature response at the highest resolution compared with the ∼25 km configuration, thus yielding stronger climate sensitivity.

More generally, we also briefly outline emerging applications of the kilometre-scale IFS-NEMO model in other European research projects, including TerraDT, which focuses on land–atmosphere coupling, and PREDDYCT, which investigates the role of mesoscale ocean eddies in seasonal-to-decadal climate prediction. Together, these efforts highlight the added scientific value of high-resolution climate modelling for understanding forced responses and informing future climate projections.