Observing urban greenhouse gas emissions – key results of the ICOS Cities project

Cities are at the heart of the climate challenge – and of the climate solutions. Responsible for a large share of fossil-fuel emissions, but also hubs of innovation and community engagement, they hold a unique position to accelerate the transition to climate neutrality.While most cities recognize the need for climate action, effective policy implementation is often hampered by a lack of timely, reliable, and spatially detailed greenhouse gas (GHG) emission data. Traditional, statistic-based inventories frequently suffer from inconsistency, time lags, and missing local detail.The ICOS Cities project (PAUL – Pilot Applications in Urban Landscapes), running from 2021 to 2025, was co-designed by scientists, policymakers, and local stakeholders to explore how techniques to quantify and partition CO2 emissions and emission reductions based of direct observations can improve informed climate action.In three pilot cities, Paris, Munich, and Zurich, ICOS Cities brought together and evaluated the most innovative measurement approaches of greenhouse gas emissions in densely populated urban areas. State-of-the-art instrumentations were deployed and innovative combinations of measurements, modelling and inventories further developed.The most important insight from the ICOS Cities project is that direct observations of GHG fluxes and concentrations combined with inverse modelling can severely support and improve inventories and general knowledge on greenhouse gas emissions from cities.The presentation will present the key results of the project and give an outline how future services can be developed based on the project results.