IVECC-impact of vegetation on regional climate and climate change simulations contributes to the joint projct QUIRCS-quantification of uncertainties in regional climate and climate change simulations. Quircs is a joint project within the German Klimaforschungsprogramm DEKLIM sponsored by BMBF (project number 01LD0026). A reliable assessment of future climate development requires an improved understanding of climate and its variability as well as a detailed knowledge of the uncertainties of the climate simulations which provide the requested information about possible future changes. This project focuses on the climate patterns of Central Europe and investigates the quality of currently used regional climate models and regionalization techniques by a model intercomparison, a substantial model evaluation, additional sensitivity studies and an extensive analysis of climate data. The major scientific aims are - to quantify the uncertainties of regional climate simulations and of observed climate data, - to investigate the sensitivity of regional climate simulations and interpolated climate data to the influence of different model parameters and data processing techniques, - and to produce a regional climate change scenario for Europe and particularly for Germany. To achieve this, a set of common model experiments and data evaluations are realized together with individual sensitivity studies and data preparations by the six project partners. The REMO model is used to carry out a baseline simulation for todays climate and for a control and climate change scenario. The control run is covering the time period 1960-1990 with a horizontal resolution of 1/6 degree. This REMO run is nested into an 1 degree REMO run, which has the boundary conditions of an ECHAM4-T106 run with the SST of the ECHAM4/OPYC3-T42 (GSDIO) run for this time period.