From Data Rocks to FAIR Peaks: With NFDI4Earth’s services towards Harmonized Metadata and User-Centered Tools for Earth System Research 

Research data management (RDM) in the Earth system sciences is complex and can be frustrating. Data come in many shapes and formats—observations, model outputs, samples, derived products—and are spread across a wide range of repositories, services, and software ecosystems. These infrastructures differ greatly in metadata quality, interoperability, and FAIR maturity. For researchers, this often means spending too much time figuring out where to publish data, how to describe it properly, or how to reuse existing datasets and software. At the same time, expectations from funders and journals on data outputs continue to rise with respect to openness, curation, and long-term stewardship. Within the German National Research Data Infrastructure (NFDI), the NFDI4Earth consortium tackles these challenges by building practical, community-driven solutions for the Earth system sciences. As developers and designers, our focus is on lowering barriers and making FAIR data and software practices easier to understand and apply in everyday research. In this contribution, we introduce two key building blocks of this effort: the Knowledge Hub and the OneStop4All. The Knowledge Hub (https://knowledgehub.nfdi4earth.de) is a knowledge graph that connects heterogeneous Earth system resources, e.g., datasets, repositories, services, software, and educational materials, using a harmonized metadata model. It harvests metadata from multiple providers—ranging from global aggregators to national and domain-specific services (see, for instance, the Helmholtz DataHub: https://earth-data.de/) - and exposes them through a well-defined SPARQL API. This allows both humans and machines to query, explore, and reuse metadata consistently, and enables developers to build custom applications on top of it. The OneStop4All (https://onestop4all.nfdi4earth.de) builds on the Knowledge Hub to offer a discovery and guidance portal for researchers. It brings together the resources in a single, coherent interface. Cross-domain search and guided navigation help users move along the research data lifecycle without having to know all standards and infrastructures upfront. A central feature is the Repository Wizard, an interactive decision-support tool that helps researchers find suitable repositories for publishing their data based on data type, discipline, and policy constraints. In addition, the NFDI4Earth Label provides a transparent, community-oriented way to communicate repository quality with respect to FAIR principles, sustainability, and relevance for Earth system sciences. Beyond discovery, the OneStop4All puts a strong emphasis on learning and cultural change. It provides integrated access to open educational resources, good-practice guides, and showcases that demonstrate the concrete benefits of FAIR and open data and software. A domain-specific chatbot complements these resources by answering practical questions on metadata, licensing, data publication, and software citation. We will showcase these services, share lessons learned from development, and highlight opportunities for community contributions. From our perspective as a distributed team of designers and software developers, combining harmonized metadata, user-centered services, and hands-on training is key to making FAIR and open research practices work at scale in the Earth system sciences.