A Tale of Many Cities: Why it Matters to Boost Subnational Climate Diplomacy in Transatlantic Relations

10:00 - 11:20 ET / 16:00 - 17:20 CET // Doors open at 15:30
Hertie School Forum + Online
A Tale of Many Cities
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The climate crisis is one of the most pressing challenges of our time. Achieving our climate goals as well as mitigating and adapting to climate change require a global effort. The subnational level must form part of this effort. Cities, regions and states are increasingly critical to keeping international climate diplomacy alive, and they have stepped up to fill the void left by nation states when climate action at the federal level stalls.

This event, as part of the TCB Conference 2023: Multilevel Action for Transatlantic Climate Success, highlighted subnational climate actions.


  • Cathryn Clüver Ashbrook, Senior Advisor, Bertelsmann Stiftung Moderator
  • Stormy-Annika Mildner, Director, Aspen Institute Germany (opening remarks)
  • Professor Dr. Christian Flachsland, the Hertie School
  • Jasmin Miah, ICLEI Head of Berlin Office
  • Erin Bromaghim, Deputy Mayor for International Affairs, City of Los Angeles
  • Martin van der Pütten, Director of Office for International Relations, City of Dortmund

Subnational actors implement national climate policies, serve as laboratories for policy innovation, and can be agenda-setters for climate action. At the same time, subnational entities can reflect differing perspectives and be a guiding post for where climate ambition needs to be strengthened. Subnational diplomacy is critical to ensuring that diplomatic doors between countries are left open throughout changing political cycles at the national level. When national political ambitions do align with subnational ambitions, subnational actors must also be elevated by national actors in the international space.