The ice flow at the margins of the West Antarctic Ice Sheet (WAIS) is moderated by large ice shelves. Their buttressing effect significantly controls the mass balance of the WAIS and thus its contribution to global sea level rise. The stability of these ice shelves results from the balance of surface accumulation, ice flow from the adjacent ice sheet, calving and basal melting or freezing due to the ocean heat flux. In order to study the interactions between the world ocean and the WAIS, we developed a Regional Antarctic and Global Ocean (RAnGO) model. It is composed of the global Finite Element Sea ice Ocean Model (FESOM) and the three-dimensional thermomechanical finite difference ice flow model RIMBAY. In a first step, our investigations focus on the interactions at the Filchner-Ronne Ice Shelf (FRIS). The ice flow model RIMBAY provides the ocean model FESOM with the geometry of the FRIS sub-shelf cavity and receives basal melting or freezing rates in return. After a complex spin-up, we obtain a present day configuration of RAnGO and perform prognostic model runs for different global warming scenarios for the next 200 years. In a comprehensive analysis, we compare the coupled model runs to parametrizations, one-way forcings and a control run. Thus, we are able to isolate the gain of the coupling and the effects of global warming. Our model results reveal a future grounding line retreat underneath Institute, Foundation and Support Force Ice Stream, whereas the grounding line positions at other regions of the FRIS remain stable. In particular, model results indicate an accelerated future ice flow within Institute and Support Force Ice Stream as an answer to ice shelf - ocean interactions, which will result in a rising sea level.