Integrated Carbon Observation System (ICOS) is a pan-European Research Infrastructure of twelve member countries and over 100 greenhouse gases measuring stations aimed at quantifying and understanding the greenhouse gas balance of Europe and neighbouring regions. ICOS stations measure greenhouse gas concentrations in the atmosphere and fluxes over the terrestrial and marine ecosystems. The ICOS stations are run and funded by national funding agencies, institutes and universities, demonstrating an impressive joint effort to enable climate change research.