World Mayors Summit 2025
3-5 November 2025
Together, the 2025 World Mayors Summit and COP30 mark a critical phase in global climate action: moving from negotiation to accelerated delivery. Mayors will meet to put their climate progress on record through the Yearly Offer of Action.
Cities will show what’s been achieved, what’s next, and how delivery will accelerate. This proof of progress builds momentum heading into COP30 to drive the urgent, concrete action needed to protect the people and places we love.
For 20 years, C40 has championed cities as the catalysts for climate action.
Our mayors set the pace for climate action. They deliver results on the ground and drive change on the world stage.
We help cities move forward and move fast
Our 97 cities represent nearly a quarter of the global economy. Together, we design, test, and improve solutions that raise the standard for everyone.
Action needs infrastructure
Explore how cities are building the foundations that raise climate ambition and strengthen their capacity to deliver action.
City action drives global change
Discover how C40 Cities and its mayors shape global finance, governance, and policy to scale climate action.
Change people can believe in
See how mayors build the public support, political will, and global solidarity that make ambitious action possible.
Smarter systems, stronger cities
Explore how transforming city systems helps scale up climate action and create more liveable cities.