Informatics efforts emerged largely in isolation across a number of different subject areas. Generally cast as the science and engineering of information systems originating in the middle of the last century, informatics has undergone many adaptations. In the last two decades, it has flourished into discipline-specific fields like geoinformatics, bioinformatics, mineral informatics, astroinformatics, and more. Recently, certain core elements in informatics have been recognized as being applicable across disciplines. Hence, efforts at systematizing the common (or core, i.e., discipline neutral) aspects of informatics have been successful, such as use cases, human-centered design, iterative approaches, and information models among others. Much work has been done to convene the Earth Science Informatics community, define Informatics and Data Science in Earth Sciences, and bring about the emergent “X-informatics”, where ‘X’ is a variable for the discipline, for example, bio, geo, chem, astro, etc. The evolution of these fields coupled with interdisciplinary research becoming widely accepted, we face new challenges arising from the increased attention to big data-driven, artificial intelligence-based approaches in general, including creating or adapting X-informatics to address data that are high-dimensional, heterogeneous, sparse, or with uncertain quality. This union session will showcase the field of X-informatics, its history, current research, and visions for the future."