This application is to support the implementation of a four-year European Earth system modelling project “GREENHOUSE GAS FLUXES AND EARTH SYSTEM FEEDBACKS” coordinated by Aarhus University and co-led by Uppsala University. The Ambition of this project (GreenFeedBack) is to enhance knowledge of the GHG dynamics in the ecosystems and link GHG in terrestrial, freshwater and marine ecosystems to provide a solid basis for estimation of regional and global climate feedback processes taking human pressure on ecosystems into account. This project will study the processes in sensitive terrestrial, freshwater, coastal and marine areas of which some are hypothesized to be tipping elements in the climate system. We will primarily focus on high-latitude terrestrial and freshwater systems, marine shelves and ocean areas and advance the process-based representation of ecosystems in EC-EARTH (implemented in WP6 and led by Uppsala University). We anticipate that a set of numerical experiments, sensitivity experiments, as well as short-term experiments for model testing and tuning, are needed.