The tropopause region and the adjacent layers of the upper troposphere and lowermost stratosphere (UTLS) are very sensitive to changes of the chemical composition and the climate. However, the knowledge about this region is still limited. Long-term observations of atmospheric chemical composition, temperature, aerosols and clouds by IAGOS help documenting changes in this sensitive atmospheric region, better understanding the cycles of climate-active gases like water vapour and ozone, and investigating the impact of climate change. The regular measurement of the vertical distribution of air quality relevant components like NO_x, O₃, and particulate matter provide essential information for the assessment of global air quality. The operational measurement of atmospheric trace constituents on board of passenger aircraft have created a dense network of collaborations with European research infrastructures, aviation industry, airlines, and the European Earth observation programme Copernicus.

In order to capture the complexity of the Earth system and the diverse interactions between the atmosphere, land surface and ocean, including the effects on all life forms, the observation data from many infrastructures from the various areas of Earth system research must be linked. The foundation stone for the necessary structures in data management and processing was laid with the EU project ENVRI-FAIR. As one of the mature infrastructures, IAGOS coordinated this task and is also significantly involved in the follow-up projects ENVRI-Hub NEXT and OSCARS beyond the completion of ENVRI-FAIR.