Cities are leading the way
The C40 World Mayors Summit 2025, co-hosted by the Mayor of London and C40 Cities Co-Chair Sadiq Khan and the Mayor of Rio de Janeiro Eduardo Paes, brought together mayors from nearly 100 C40 cities, alongside business leaders, philanthropists, investors, academics, and civil society.
This year’s Summit kicked off the COP30 Local Leaders Forum, co-hosted by Bloomberg Philanthropies and the COP30 Presidency. The Forum put local leadership at the heart of global negotiations, showcasing scalable city-led solutions and ensuring local priorities shaped the outcomes of COP30.
Taking place from 3-5 November in Rio de Janeiro, just days before COP30 in Belém, the Summit marked a critical moment for city-led climate action. Building on two decades of C40 Cities leadership, it showcased innovative solutions from cities worldwide, demonstrated what’s possible through delivery-focused collaboration, and built momentum ahead of COP30.
Cities are already delivering practical, urgent solutions to the climate crisis
The Yearly Offer of Action
To deliver the Decade of Acceleration called for by the United Nations Secretary General, decision-makers need to act now, not in five or ten years.
At the World Mayors Summit 2025, C40 Cities and the Global Covenant of Mayors (GCoM) showcased how cities are moving from negotiation to delivery, turning climate pledges into real-world progress.
The Yearly Offer of Action sets out what cities have achieved, what comes next, and how we’re accelerating delivery year after year until climate breakdown is under control.
News & Announcements
Local Leaders Forum
Local Leaders Forum Joint Statement
As world leaders gathered in Belém for COP30, more than 14,000 local leaders came together to stand behind a message for national governments at COP30, affirming their unwavering commitment to fighting the climate crisis with real on-the-ground solutions.
Local Leaders Awards
As part of the Summit, the Bloomberg Philanthropies Local Leaders Awards honoured city and regional governments delivering standout climate action. The Awards recognised one Brazilian and one global leader across key COP30 priority areas:
- Multilevel partnerships
- Just energy transition
- Adaptation and resilience
- Health and well-being
Sponsors
The C40 World Mayors Summit was presented as part of the COP30 Local Leaders Forum, co-hosted by the COP30 Presidency and Bloomberg Philanthropies:
With additional support from:
