Climate change calls for rapid and extensive transition worldwide, and citizen empowerment is a key to change at city district level. A backcasting study in Stockholm's recent brownfield development Hammarby Sjöstad explores this, asking: ‘What must local actors do to reduce citizens’ consumption-based emissions by half till 2030? ‘Individual actors’ transition pathways are explorative and concern ground transport, food, housing, aviation and other consumption. In a quantitative scenario, these pathways are scaled up to district level, asking ‘How many actors must do how much, to reach the target?’ An interwoven qualitative approach highlights organizational aspects. The upscaled backcasting scenario is normative, in part prognostic and explorative. Feasibility is ensured through integrating the issues of ‘What to Change’ and’ Change by Whom’. Results indicate that the local target is feasible if most actors maximize the use of their individual transition pathways. Additionally, Stockholm City and other external actors must realize their targets, including technological development. New organizational models must involve energy managers, supermarkets, car sharing companies etc. as change agents. The whole is catalyzed by a citizen engagement process, driven by local network builder and transition agent ElectriCITY, enabled through action research within the Sharing Cities Sweden research and innovation program. © 2021 The Author(s)