The C40 Cities Climate Leadership Group (C40) is a network of the world’s megacities committed to addressing climate change.

Acting both locally and collaboratively, C40 Cities are having a meaningful global impact in reducing both greenhouse gas emissions and climate risks. C40 brings together a unique set of assets and creates a shared sense of purpose. C40 offers cities an effective forum where they can collaborate, share knowledge and drive meaningful, measurable and sustainable action on climate change.

Explore an interactive list of the C40 Cities and our Networks and Research connecting them.

C40 Cities: Showing the Way Forward

Take a ride with us through five of our cities to see actions and progress.

See the C40 like never before in this short video that takes you on a journey through member cities London, Johannesburg, Jakarta, Rio de Janeiro and New York. 

Meet the C40 Cities taking action.

A Message from the C40 Chair, Mayor Eduardo Paes

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Speaking at the C40 Mayors Summit in Johannesburg, South Africa

"We are on the eve of a decisive moment in the fight against climate change. The United Nations debates the adoption of new Sustainable Development Goals and negotiates an agreement to replace the Kyoto Protocol. We mayors have a prominent role to play in this process. We are engaging in city diplomacy by delivering concrete results and building leadership. We have sent a letter to the UN to acknowledge that urban issues should be a priority."

Learn more about the C40 Chair, Mayor of Rio de Janeiro, Eduardo Paes.