Accessible and interoperable data are at the heart of data-driven innovation in the European Green Deal. This data, combined with digital infrastructure and artificial intelligence solutions, facilitate evidence-based decisions and expand the capacity to understand and tackle environmental challenges. How to operate and discern among all the data available in the Green Deal Data Space? There are many vocabularies for variables and observations, but a formalization is lacking. AD4GD proposes to use Essential Variables! Essential Variables (EVs) have been defined by different communities as sets of variables that are crucial for characterizing and monitoring systems across space and time, providing insight into underlying processes and their changes, and/or feeding indicators that inform environmental policies at multiple scales. The AD4GD proposal for EVs semantic tagging includes using OGC RAINBOW and STAplus. Check how in this poster. This poster was displayed at the GEO Week 2023 Ministerial Summit that took place in Cape Town (South Africa) between the 6th and th 10th of November.