SWEET is a highly modular ontology with more than 6000 concepts organised in over 200 separate ontologies covering Earth System Sciences. Top-level concepts include representation (mathematics, space, science, time, data), realm (ocean, land surface, terrestrial hydroshere, atmosphere, etc.), phenomena (macro-scale ecological and physical), processes (micro-scale physical, biological, chemical, and mathematical), human activities (decision, commerce, jurisdiction, environmental, research). SWEET was originally developed by NASA Jet Propulsion Labs and is now officially under the governance of the ESIP Community.