Advancing Earth System Models to increase understanding of Earth system change

Project results are expected to contribute to all of the following expected outcomes:

• Advanced understanding and capability to predict the future evolution of the Earth system, at global to local spatial scales and from weather to climate timescales, including the socio-economic and environmental impacts of these changes;
• Advanced understanding and capability to predict regional climate variability, including extreme events and regional water cycle, in particular, regional precipitation;
• Strengthened collaboration and cross-fertilisation across available approaches to Earth system and climate modelling science, enabling a joint contribution to the next generation of Earth system models (ESMs);
• Long-term science, modelling and evidence base to support European and international polices are advanced.

ESMs are the primary tools used for assessing future changes in the climate system. They have increased in their resolution and realism over the past two decades. Despite these advances, there remain several poorly understood and simulated processes, interactions and feedbacks that limit their ability to deliver accurate predictions and projections of global and regional Earth system change, and to aid understanding and quantifying future climate variability. Specially challenging is how variability interacts with extreme events (including compound ones), in particular related to precipitation and water availability (both excess and scarcity).

Actions should address all of the following aspects:

1. Improving the simulation of the coupled Earth system and its sensitivity to natural and anthropogenic forcings, with a better representation of key Earth system and climate feedbacks and processes, including, among others, one or more of the following advances^[1]:
   • The interplay between global change, regional climate variability, and changes in climate and weather extremes;
   • Terrestrial-ocean-climate interactions;
   • Coupled climate-carbon-water cycle feedbacks;
   • Coupled climate-ocean-ice interactions;
   • Aerosol-cloud-climate forcing and feedback;
   • Climate-vegetation-fire interactions;
   • Climate-air quality interactions;
   • Interactions between land use scenarios (in terms of changes in the land use and surface, such as those related to carbon dioxide removal, with consequences on the water and carbon cycles, albedo and aerosols) and regional climate.
2. Increased collaboration across different model development approaches encompassing the range of available model resolutions and model realism.
3. Bring together and further improve existing and new observational and reanalysis datasets, models, emulators, and analysis tools to facilitate rapid and in-depth bias identification, model calibration and validation, and evaluation and understanding of model simulations.

Actions should exploit the opportunities offered by state of art digital technologies such as machine learning, big data analytics or Artificial Intelligence (AI). They should promote the highest standards of transparency and openness, extending to aspects such as assumptions, protocols, code, and data that is managed in compliance with the FAIR principles^[2]. Beneficiaries of EU funding are required to publish results data in open access repositories and/or as annexes to publications, and provide full openness of any new modules, models or tools developed from scratch or substantially improved. Projects should take into account, during their lifetime, relevant activities and initiatives for ensuring and improving the quality of scientific software and code.

All projects funded under this topic are strongly encouraged to connect, coordinate, and participate in networking, intercomparison and joint activities to exploit synergies and maximise complementarities between them. They should envisage clustering activities with any other relevant projects (in^[3] and outside of Horizon Europe) for cross-projects cooperation and exchange of results. Proposals should earmark the necessary resources for these purposes. Results from relevant past and ongoing projects from previous calls of this Destination and other relevant projects on ESM should be considered and strong feedback and coordination with projects funded under the topics HORIZON-CL5-2025-06-D1-01 “Climate simulations data and knowledge for optimal support of IPCC Assessments and International Policy” and HORIZON-INFRA-2025-01-SERV-02 (area on research infrastructure services to improve the understanding and prediction of future climate changes and their impact) is expected.

International cooperation is encouraged, in particular with the Global South^[4], to promote capacity and consensus building, for example, by training early career researchers.

[1] The evaluation will be based on the standard Horizon Europe evaluation criteria, regardless of the number of the aspects covered.

[2] FAIR (Findable, Accessible, Interoperable, Reusable).

[3] For example, relevant projects funded under the Horizon Europe calls Climate sciences and responses.

[4] In absence of a single formal definition of the Global South, the list of low- to middle-income countries automatically eligible for Horizon Europe funding should be used for this purpose – see the Horizon Europe List of Participating Countries on EU Funding and Tenders Portal for up-to-date information