From citizens to citizens: information sharing for evidence-based response to climate change

In recent decades, citizen science has emerged as a key approach to engage the public in research, enhancing scientific productivity and democratizing science. However, the effective use of citizen-generated environmental data for climate change analysis and decision-making remains limited due to the heterogeneity of data sources, formats, and platforms, which hinders interoperability and reuse within existing environmental data infrastructures. This paper presents the Environmental Impact Hub (EIH), developed within the EU Horizon 2020 I-CHANGE project, as an interoperable data infrastructure designed to integrate heterogeneous environmental observations from citizen science activities, low-cost sensors, institutional monitoring networks, and Earth observation systems. Guided by the principle ‘from citizens to citizens’, the EIH adopts a modular architecture based on a Data and Information Broker, a Citizen Observatory Archive, and an interactive Dashboard, enabling data discovery, access, and reuse through open standards and APIs. The infrastructure was tested across eight Living Labs in Europe and beyond, demonstrating its capability to ingest, harmonize, and expose heterogeneous datasets, and to support interoperability with major initiatives such as Copernicus, GEO/EuroGEO, and the Green Deal Data Space. The EIH exemplifies a scalable, FAIR-aligned approach to integrating citizen-generated data into Digital Earth ecosystems, supporting climate-related environmental applications and data-driven services.