EC-Earth is one such model system, and it is being used in 11 different countries and by up to 24 meteorological or academic institutions to produce reliable climate predictions and climate projections. It is composed of different components, with the atmospheric model OpenIFS and the ocean model NEMO being the most important ones.

EC-Earth is one of the ESMs that suffer from a lack of scalability when using higher resolutions, with an urgent need for improvements in capability and capacity on the path to exascale. Our main goal is achieving a good scalability of EC-Earth using resolutions of up to 10 km of horizontal spatial resolution with extreme parallelization. In order to achieve this, different objectives are being pursued:

(1) The computational profiling analysis of EC-Earth. Analysing the most severe bottlenecks of the main components when extreme parallelization is being used.

(2) Trying to exploit high-end architectures efficiently, reducing the energy consumption of the model to achieve a minimum efficiency in order to be ready for the new hardware. For this purpose, different High Performance Computing techniques are being applied, for example the integration of a full parallel in- and output (I/O), or the reduction in precision of some variables used by the model, maintaining the same accuracy in the results while improving the final execution time of the model.

(3) Evaluating, if massive parallel execution and the new methods implemented could affect the quality of the simulations or impair reproducibility.