CarboEurope is a Cluster of European research projects which aims to quantify the carbon balance of the European continent by a dual constraint approach. This combines bottom-up predictions made from ground-based measurements and models with top-down verification by atmospheric measurements and inverse models. More information can be found at http://www.bgc-jena.mpg.de/public/carboeur/. ... quantifying the carbon budget of the European continent by the upscaling of local process measurements, carbon inventories and eddy flux data and by a synthesis of literature data. A close collaboration with the modelling efforts of the projects in the CarboEurope Cluster and with the CarboEurope Steering Committee will be essential.