This paper discusses the vision and requirements of a highly interactive workbench which supports decision makers using distributed resources including models as automated components of an integrated environmental decision support system. The concepts discussed are results of the SUDPLAN project, an EU FP7 project which aims at developing advanced tools for climate change adaptation for city planners and city managers. To this end, SUDPLAN incorporates access to climate change models and model results as an important common service. This paper provides an overview of SUDPLAN, with special emphasis on the highly interactive Scenario Management System. It also includes an overview of the user requirements derived through a user-centred design process engaging highly diverse user representatives of four pilot application cities.