Carbon-neutral targets are a ‘new normative’ for cities and regions around the world. Such targets call for rapid system transformations, beyond the normal remit of urban-regional planning. In response, we propose a framework of theory and practice, in three parts: ‘trading zone’ concepts for collaborative planning; ‘scenario back-casting’ for longer horizons; and ‘synergistic thinking’ for systems transformation. We demonstrate this with the carbon-neutral journey of Greater Manchester. The results suggest the ‘new normative’ for cities and regions can be greatly facilitated by ‘synergistic scenario planning’, in theory and practice.