The Global Emissions InitiAtive (GEIA), a major crosscutting activity of IGAC https://igacproject.org, is an international community effort dedicated to emissions understanding, information exchange, and competence building. Since it was created in 1990 under the International Geosphere-Biosphere Programme (IGBP), GEIA has been providing necessary, quality assured emission information for comprehensive global assessments of past, present and future atmospheric chemistry, air quality and climate change. GEIA’s ongoing initiatives advance understanding, distribution and use of timely information to the research, assessment and policy communities. GEIA also provides information on emissions on regional and megacity scales, assesses land-water-air exchange processes, and develops platforms for information sharing and data evaluation. GEIA aims to be the key forum dedicated to expanding emissions knowledge in a rapidly evolving society by: 1) building the scientific basis of emissions understanding and estimates, and facilitating analysis of emissions processes; 2) improving access to emissions information; and 3) strengthening the community of emissions groups involved in research, assessment, operations, regulation and policy.