World Cities Day 2026
Cities driving community-led solutions to climate resilience
As we face unprecedented impacts from climate breakdown, cities around the world continue to lead the way against extreme heat, flooding and water shortages. See how C40 cities are creating community-led solutions to adapt to a changing climate, build urban resilience and ensure a fair and just future for all.
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.
Global Urban Data Centres Pact
As data centres grow rapidly in urban areas, the need for local governance that delivers sustainability and real benefits for residents has never been greater. Cities are shaping the future of the digital infrastructure that powers our digital lives, ensuring data centres are sustainable and benefit local communities. Endorsing mayors are calling on the industry to join cities in turning this ambition into action.
Strengthening cities to deliver
Learn how cities create the conditions for effective climate action through smarter planning, inclusive decisions, and climate-aligned budgets.
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.