Marseille is building coalitions from the ground up. Rather than expecting climate action to flow from policy, the city and six partners are mobilising citizens in three neighbourhoods and companies across four business districts — creating the community-level demand, practice, and legitimacy that enables policy to follow. Through the "Tables de l'écologie populaire" (popular ecology tables), three climate ambassadors work in vulnerable and mixed neighbourhoods to help residents identify their own priorities, take action, and formalise demands to the city. Simultaneously, three business networks support over 850 companies in mobility, renewable energy, waste, and water.