Bridging the fragmentation gap in Earth System Science: ITINERIS as a blueprint for national RI consolidation and integration

Addressing complex Earth System Science challenges is currently hindered by a pervasive fragmentation of the research ecosystem. This disconnect extends beyond data dispersion to include siloed organizational structures and isolated disciplinary communities, limiting the potential for holistic environmental analysis and cross-domain innovation.
 
In response to the session's call for successful synergy examples, we present ITINERIS (Italian Integrated Environmental Research Infrastructures System). ITINERIS serves as a strategic operational model for shaping the Research Infrastructure (RI) landscape by integrating the Italian national nodes of 22 RIs across four critical domains: atmosphere, marine, terrestrial biosphere, and geosphere. This network encompasses ESFRI Landmarks (ACTRIS, EMSO, ICOS, Euro-Argo and LifeWatch), ESFRI Projects (e.g., e-LTER, DANUBIUS), EU RIs (e.g., ECORD), and key national RIs (e.g., the Laura Bassi research ship).
 
We demonstrate how ITINERIS contributes to the European Open Science Cloud (EOSC) through three core pillars:

•    The ITINERIS HUB: An integrated digital platform that transforms fragmented RI repositories into a unified discovery and analysis layer. By combining a centralized metadata catalogue (populated via automated harvesting) with thematic Virtual Research Environments and advanced access and training services, the HUB acts as a fundamental building block of the Italian EOSC Node, enabling advanced analyses, AI‑driven workflows and models across more than 500,000 environmental datasets, backed by a vast array of services and resources from diverse RIs
•    Cross-Disciplinary synergies: Innovative use cases that overcome domain boundaries, such as Nature-Based Solutions and climate mitigation. These scenarios demonstrate the power of combining atmospheric observations with marine and terrestrial ecosystem data, enabling a holistic assessment of environmental compartments that was previously unattainable due to infrastructure silos.
•    National Access Framework: A harmonized operational framework serving as a blueprint for future nationally-funded access programs. Building on the success of the ITINERIS-ACTRIS pilot call, which tested a unified governance for physical, remote, virtual access and hybryd access, this model provides a validated approach for reducing administrative barriers  and expanding access opportunities for the wider user communities.
 
We invite the community to explore ITINERIS as a replicable model for national aggregation strategies, discussing the governance and sustainability challenges of this multi-stakeholder initiative and sharing best practices for other national clusters. 
By aligning national strategies with European standards like FAIR and ENVRI-FAIR, ITINERIS provides a validated roadmap and a scalable template for 'joining forces' to build a unified, interoperable European environmental research landscape.