What they do
C40 is a network of 96 of the world's largest cities committed to addressing climate change. Member cities represent over 700 million people and one quarter of the global economy. C40 facilitates knowledge sharing, technical assistance, and collective action on urban climate plans including building efficiency, clean transport, waste management, and climate resilience.
Why they matter
Cities produce over 70% of global CO2 emissions. C40 cities collectively have more climate impact than most nations. The network's peer pressure model works: cities compete to lead on climate action, share proven strategies, and hold each other accountable to deadlines. Their climate action plans are specific, measurable, and publicly tracked. When a C40 mayor commits to fossil-free transport by 2030, the network's reporting mechanisms ensure that commitment is visible and accountable.
How to support
Advocate for your city to join C40 or strengthen its climate commitments. C40's publicly available climate action plans provide templates for civic engagement. Follow C40's reporting to hold your local government accountable.
Key project to explore
The Deadline 2020 initiative required all C40 cities to produce Paris Agreement-compatible climate action plans with specific sector-by-sector emissions reduction targets and public reporting timelines.