The BITS project is building a Terminology Service (TS) for Earth System Sciences (ESS TS). As a first step it will develop this service for the subfields of climate science (results from climate simulations) and geodiversity collections (representing Earth’s diversity of i.a. rocks, fossils, soils, sediments). The project will use the existing Terminology Service of the TIB – Leibniz Information Centre for Science and Technology, which currently contains  190 ontologies, more than 1.2 million terms and over 26,000 properties from a range of domains such as architecture, chemistry, computer science, mathematics and physics. It has implemented the ESS collection within the TIB TS by now, which already contains relevant terminologies for the ESS and to which further relevant terminologies will be added. The ESS TS will be integrated into the two different data repositories of the German Climate Computing Center (DKRZ) and the Senckenberg - Leibniz Institution for Biodiversity and Earth System Research (SGN):DKRZ will use the TS to develop a more user-friendly search for its World Data Center for Climate (WDCC) repository. The terminologies will be used to suggest additional and more relevant search terms to users. This will help users who are unfamiliar with the terminology used by the climate community to find the right keywords for their data search and to get accurate and high quality search results. SGN will use the TS to add standardised structured metadata to geothematic Digital Specimens in their digital collections. This will increase the FAIRness of collection data, i.e. foster self-contained discovery and processing of Digital Specimens by software agents or, in short, machines (machine actionability).   The experience gained in building the ESS TS and integrating it into the repositories at DKRZ and SGN will be used to create blueprints to connect later on other Earth System Science repositories to the TS. We also aim to work closely with NFDI4Earth and the wider ESS community, and with TS4NFDI as the NFDI base service project for terminology services.As BITS evolves, ESS TS will be supplemented by additional components e.g. to support FAIR semantic mappings (leveraging on SGN’s mapping.bio service). However, feedback from the wider ESS community about expectations for such a service and their needs is welcome and required for the project. Our aim is a Terminology Service, which serves as a valuable resource for researchers, students, professionals and developers in ESS, providing them with accurate and consistent terminology to enhance their work, improve communication and data sharing and advance knowledge in their respective fields.