Who we are
C40 is a global network of nearly 100 mayors of the world’s leading cities that are united in action to confront the climate crisis.
Mayors of C40 cities are committed to using an inclusive, science-based and collaborative approach to cut their fair share of emissions in half by 2030, help the world limit global heating in line with the Paris Agreement, and build healthy, equitable and resilient communities. C40 supports mayors to do this by:
- Raising climate ambition through 1.5°C climate action plan support, high-impact accelerators and fostering innovation.
- Building equitable and thriving communities via global and regional programmes.
- Building a global movement through robust international advocacy and diplomacy.
- Scaling up climate action and sharing best practices across high-impact sectors.
- Facilitating access to finance for investment in green jobs and projects that improve resilience in cities.
Our cities
Cities in the C40 network earn their membership through action.
Our Leadership Standards set the minimum requirements for all member cities and safeguard the integrity of C40 as a network of climate leaders.
Membership operates on performance-based requirements, not on fees, and every city in the C40 network is reviewed annually against our Leadership Standards.
C40 Leadership Standards 2025–2030:
IMPLEMENT
Cities are implementing ambitious climate actions to:
- Deliver their city-wide GHG emissions targets by 2030 (or earlier), reduce the use of and end support for fossil fuels and address emissions from urban consumption
- Address priority risks, enhance resilience and deliver city-wide adaptation goals and targets
- Deliver stronger and more equitable outcomes for all
LEAD
- By 2030 cities have established comprehensive governance structures that ensure climate targets and considerations are integrated across decision-making, including introducing climate budgeting
- Mayors are using their leadership platforms to broaden the global, regional and local impact of C40 cities’ climate actions and collective missions.
C40 mayors have been at the forefront of climate leadership for over 15 years, driving the conversation around climate action and environmental justice to place these issues front and centre in our local policies and on the international agenda.
Our values
In 2024, C40 cities embarked on a process led by our staff to develop organisational values.
We aimed to build a cohesive work culture that links to agreed behaviours and informs potential staff and partners of how we aim to work through our values.
We developed our Values Framework, providing clear guidance on how we should work and ensuring consistent behaviours across the organisation. We have also updated key internal processes so that by understanding and prioritising our values in our day-to-day work, we will naturally make more informed and authentic decisions aligned with them.
C40 Annual Reports
Read our C40 Annual Report 2023 in French, Mandarin, Portuguese and Spanish.
Access more:
C40 Annual Report 2019
C40 Annual Report 2017