While urban sustainability has very pragmatic local roots, its relevance has elevated to the highest levels exemplified by the new UN special envoy for cities, Michael Bloomberg. Meanwhile, the international climate negotiations at the UNFCCC develop their own secondary approach avoiding the stall-mate of the legal negotiations by introducing workstream two where again cities and their proven best practices in climate change mitigation play a crucial role as will be presented in Lima in December 2014. The project Post-Carbon Cities of Tomorrow faces the challenge of linking all these various levels of governance – local, regional, national, European and global – while still being relevant in terms of results and outcomes for each single layer. While this is still a work in progress, first ideas and approaches will be presented and discussed.