In the context of the preparation of a CCS project in Romania (onshore), this project aims to develop an innovative environmental monitoring methodology for potential onshore CO2 geological storage projects. This methodology supports storage operators who are obliged to implement monitoring in all phases of the storage project based on the monitoring plan (mandatory according to Law 114/2013 for geological storage of CO2 in Romania) resulting from the risk analysis. The innovative methodology will be based on the implementation of geophysical, geochemical and biological methods of environmental analysis to highlight possible CO2 leaks from the storage reservoir. The project will also demonstrate the feasibility of less commonly used geophysical methods for monitoring geological CO2 storage. By testing the methodology on natural analogues of geological CO2 storage, areas with natural CO2 emissions and natural CO2 reservoirs, we aim to understand the mechanisms that ensure the integrity of a storage site, as well as the mechanisms of CO2 migration to the surface. The project results will be integrated into a database developed according to FAIR principles.