World Mayors Summit Day 3

We do this for our today, we do this for our tomorrow, and we will do this together.

This was the message from youth activists at the 2025 World Mayors Summit.

Young people from all over the world, including London, Freetown, and Vanuatu, are at the World Mayors Summit to share how they are working with cities and mayors to deliver powerful climate action on the ground.

During the World Mayors summit, it was announced that the Bloomberg Youth Climate Action Fund, where C40 Cities is a partner, will expand to support 300 cities worldwide. The fund supports young people aged 15 to 24 to design and deliver climate solutions in their communities. The initiative is an opportunity for cities to meaningfully engage with and fund youth's work on climate.

Speaking about the expansion of the fund, CEO of Bloomberg Philanthropies, Patricia E. Harris, said:

We'll be able to triple the number of cities we reach, triple the number of youth we engage and hopefully, triple our impact. Together with participating cities, we're giving the next generation a chance to step up to the fight against climate change.

The EU commits to stronger climate action

The European Commission announced today that the EU has officially endorsed CHAMP - the Coalition for High Ambition Multilevel Partnerships - and in doing so committed to continue working with cities and regions to deliver stronger climate action.

"The European Union has officially endorsed CHAMP because it's a timely framework to strengthen cooperation across all levels of governance. Ambitious action requires all hands on deck." - Teresa Ribera, Vice-President of the European Commission

Representing a collective EU position, this endorsement is underpinned by Europe's vast experience in multilevel governance and partnerships, highlighting the central role of cities and regions in climate ambition and implementation.

The EU's commitment adds significant momentum to the role of local and subnational actors as the world prepares for COP30 in Belém.

C40 World Mayors Summit Exhibition

Cities have been proudly displaying their achievements at the C40 World Mayors Summit exhibition. Interactive displays showcasing projects in C40 cities are highlighting the tangible progress being made on clean energy, urban design, and air quality.

One of the projects shown was about Breathe Cities - an ambitious initiative supporting cities around the world to cut their air pollution and climate emissions.

Thank you to IBM for sponsoring the C40 World Mayors Summit exhibition and helping shape the future of sustainable cities.

The power of collaboration

C40 Cities and the We Mean Business Coalition brought together mayors and senior business leaders to explore how city-business collaboration can accelerate climate action ahead of COP30.

Mark Watts, Executive Director of C40 and María Mendiluce, CEO of We Mean Business Coalition, led the conversation at the World Mayors Summit, focusing on how local partnerships can lead to real progress.

The mayors of Tshwane and Oslo shared their cities' experiences and proved how working with businesses can help scale up climate action and drive tangible results in the places where people live and work.

Creating change together

C40 mayors from different regions met at the World Mayors Summit to share solutions that deliver cleaner air, greener jobs, and more affordable cities.

This morning, mayors from North America met with C40 Cities Co-Chair and Mayor of London, Sadiq Khan, to share progress, exchange ideas, and strengthen their collective vision for climate leadership.

There are no territories on ideas; we must share our ideas across borders."

Cam Guthrie, Mayor of Guelph, Canada

Brazil scales up climate projects

A major new partnership announced today will help 50 Brazilian cities deliver more than 20 climate projects by 2027, with support from Bloomberg Philanthropies, C40 Cities, the Global Covenant of Mayors, and the Brazilian National Front of Mayors (FNP).

The initiative will focus on sustainable transport and low-methane waste management, directly linked to federal programmes. Ten Amazonian municipalities will also receive support to design their first Climate Action Plans, helping protect vulnerable communities and ecosystems.

Working in the spirit of mutirão, a broad coalition of national partners will ensure delivery is collaborative and creates a model of multilevel governance that can inspire countries worldwide.

This effort reinforces Brazil's COP30 Presidency and its leadership in the CHAMP coalition, showing how cities and national governments can work together to accelerate climate action. Read more here.

Mayors kick off discussions on data centres

The Lord Mayor of Melbourne, Nicholas Reece and the Mayor of Phoenix, Kate Gallego, brought mayors together at the World Mayors Summit to kick off an initiative to harness the opportunities and address the environmental impact of data centres and AI infrastructure in cities.

Whilst recognising data centres as an important economic driver, the group believes this must not be at the cost of increased carbon emissions, air pollution, water scarcity, and local consumer energy prices. Find out more.

Pledging future progress

At the World Mayors Summit, city leaders presented their yearly offers of action.

The yearly offers of action tie in to the Brazilian COP30 Presidency's call for a Global Mutirão - a collective effort to deliver on climate commitments - and add immediacy and accountability to the climate promises made by elected officials.

From Barcelona installing solar panels and cooling systems in schools to Santiago transforming urban spaces with 33 new pocket forests, C40 and GCoM mayors are taking bold steps in the next 12 months to protect their residents and the planet. Read all the yearly offers of action here.

The road to COP30

As the summit came to a close, Mike R. Bloomberg, UN Special Envoy on Climate Ambition and Solutions, and Founder of Bloomberg Philanthropies, addressed the room via video and thanked cities around the world for their leadership and urged them to continue to inspire nations to protect the people and places we love: "Cities and regions will keep leading the way forward."

United at COP30 Local Leaders Forum World Mayors Summit, mayors and city leaders presented three clear and concrete offers to national governments gathering at COP30, so, together, they can meet the urgency of this decisive decade for climate action.

1. Helping countries achieve their national climate goals by actively engaging as partners in implementation and promoting a just and resilient transition.
2. Ensuring a robust pipeline of over 2,500 transformation and bankable local projects to help localise and channel climate finance for both mitigation and adaptation.
3. Advancing multilevel action and collaboration to make the COP process one of implementation and accountability.

Anne Hidalgo delivered the statement on stage and added, "Today, we have the opportunity to write a new page."

The co-host of the World Mayors Summit 2025, Mayor of Rio Eduardo Paes, captured the importance of collaboration as we move closer to COP30 in Belem.

"It's clear to me: city leadership can help shift COPs from negotiation to delivery. And it is for this reason that we call for greater inclusion of cities and subnational governments in the COP process - not as guests, but as true partners."

To the world leaders gathering in Belém: local leadership is ready to join you in a true global mutirão - working side by side to turn ambition into action, and promises into progress.

Mayor of Rio de Janeiro, Eduardo Paes Group photo during COP30 Local Leaders Forum in Rio de Janeiro, Brazil, on Tuesday, November 4, 2025.