The Integrated Carbon Observation System (ICOS) Research Infrastructure monitors greenhouse gas (GHG) concentrations and fluxes (as well as a wide array of relevant ancillary variables) at 140 atmosphere, ecosystem and ocean stations distributed across Europe and beyond. All measurements are fully standardized and quality-controlled throughout the network, and optimized to study the interactions between Global changes and ecosystem functioning. ICOS provides fully open-access data, exceptionally well-equiped stations (welcoming researchers, scholars, and companies), as well as knowledge and timely information for policy makers and the general public. Long-term (20 years) high-quality GHG data are scarce, despite their relevance for assessing trends in GHG balances, or for quantifying the impact of climate extremes or of policy measures. ICOS thus delivers unique data that are freely available and fully traceable for any user around the globe. The Flemish participation in ICOS involves six (= four ecosystem plus two ocean) monitoring stations, as well as co-hosting one of ICOS' central facilities (Ecosystem Thematic Center) and the coordination of the Belgian ICOS network.