Scenario-based approaches are widely accepted aids to decision-making processes. In most cases, scenarios in design provide alternative courses of action, which are evaluated and compared to identify a preferred option. This paper accepts that planning and design frameworks used to create such scenarios structure ambiguity and, thereby, emphasize certain kinds of uncertainty. It is argued that in the context of the Anthropocene and the emergence of associated novel social and biophysical relationships, these uncertainties of conceptualization provide a valuable basis for scenario development. These are referred to as 'scenarios within design'. The geodesign framework is examined as an illustration.