The SUDPLAN proposal aims at developing an easy-to-use web-based planning, prediction, decision support and training tool, for the use in an urban context, based on a what-if scenario execution environment, which will help to assure populations health, comfort, safety and life quality as well as sustainability of investments in utilities and infrastructures within a changing climate. This tool is based on an innovative and visionary capacity to link, in an ad-hoc fashion, existing environmental simulation models, information and sensor infrastructures, spatial data infrastructures and climatic scenario information in a service-oriented approach, as part of the Single Information Space in Europe for the Environment (SISE). It will provide end users with 3D modeling and simulation as well as cutting edge highly interactive 3D/4D visualization, including visualisation on real 3D hardware. The tool includes the SUDPLAN Scenario Management System and three so-called Common Services, which downscale regional climate change models using local knowledge, and which will be available for use in all of Europe. Both components will contribute to improved assessment of urban climate change impact. Vital aspects of climate change are considered in 4 carefully selected urban pilot applications located in Austria, the Czech Republic, Germany and Sweden. They cover such diverse applications as: a) extreme rainfall episodes causing problems with b) uncontrollable, extremely localized runoff, and c) for drainage and sewage systems, d) hazardous air pollution and high ambient temperature episodes causing health risks, e) social dynamics (movement of people) as function of climate change and quality of living. Through innovative ICT, SUDPLAN contributes to SISE, provides new perspectives for a distributed service market, reinforces European leadership in the research area and fosters the capacity to cope with climate change impacts in urban environments.