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 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. Using a camera mounted on a city bike program cycle, meet C40 Mayors and their senior sustainability leaders, and hear – and see – some of the innovative actions they are taking in their cities. You will also learn about the common challenges facing our cities and have a clearer understanding of why cities working together to build a more sustainable future can save the planet. Their progress is remarkable and so are their stories.

Meet the C40 Cities taking action.

Our research shows more than proof of action — it is also an expression of C40’s opportunity to make an even greater impact on climate change going forward.

C40 research
Acting both locally and collaboratively, cities are making a meaningful global impact by implementing sustainability practices.
Explore our latest research further to learn more about our work.