The evaluation of the impact of climate change on deltaic systems implies studying a multi-component system in which the complexity of links is high enough to present doing it as a whole. Because of this, it is a reasonable approach to study separately the behaviour of each element, to be afterwards linked into a general conceptual model for deltaic behaviour. Moreover, in the case of largely regulated deltas, the main impacts of climatic change will be marine-related since those related to the catchment areas will be severely damped by river regulation and management policies. This fact implies that coastal fringes may become the main frontier between the delta and climatic change effects. In this context, a methodology to study climatic change impacts on deltaic coastal fringes is here presented. It will be further developed on two companion papers dealing with the study of driving terms and coastal response. As coastal processes act at different time and space scales, determining the ‘reference’ – initial – situation must be done taking into account the inherent system dynamics. It is thus unrealistic to characterize the initial stage as a static one. In order to avoid this simplistic approach, a comprehensive approach to the coastal system must be employed, with three different scales (long-term/large scale, medium term/scale and episodic).