“Across the world, cities are showing that transitioning away from fossil fuels is not only possible, but it is already happening and delivering real benefits for people,” said Caterina Sarfatti, C40’s managing director for political strategy and advocacy. “At a time when households are facing rising energy bills, supply shocks, and the growing impacts of climate change, our toxic dependence on fossil fuels is exposing communities to instability and risk.

“From lower energy costs to cleaner air and more resilient communities, this transition is improving lives today while securing our future. And cities are where this transition moves from words to facts. Mayors are electrifying transport, scaling clean energy, training the workforce and making homes more efficient and affordable, proving that we can grow stronger economies while reducing our reliance on volatile fossil fuel markets. This is an opportunity to build healthier, more affordable, and safer communities. And cities are ready to lead.”

City climate action at scale

C40 Cities highlights how local governments are already delivering solutions at scale. From London’s world’s largest clean air zone to Melbourne’s collective renewable energy purchasing, which now supplies 100 per cent of municipal operations, cities are accelerating the transition while reducing costs.

In Curitiba, Brazil, public procurement for solar energy is cutting energy bills by 30 per cent in public buildings while creating good, green jobs. Johannesburg’s US$140m green bond has funded renewable energy and efficiency projects, showing how strong investor demand can accelerate city-led climate action.

Warsaw is supporting low-income households to transition directly to clean heating systems, helping to reduce energy poverty while cutting air pollution where it’s needed the most. And in Colombia, Bogotá created the first designated low-emission zone focused on reducing traffic and industrial pollution (Zuma) in one of the city’s most vulnerable and heavily polluted neighbourhoods to improve air quality and public health, benefiting almost 40,000 people. 

Crucially, cities are recognising that a green economy is only as strong as its workforce. To ensure this transition promotes inclusive growth, local leaders are proactively addressing the skills gap by reorienting the workforce through targeted training and education. C40 analysis across 25 cities – including in Colombia and Brazil – shows that up to six million additional workers might be needed by 2040. By partnering with labour unions and industry leaders, cities are creating pathways for workers in sunsetting industries to transition into high-growth sectors like solar installation, EV maintenance, and green construction.

These actions are part of a broader, shared commitment by C40 mayors: to halve fossil fuel use in cities by 2030. Progress is underway but C40 said the pace and scale of change depend on stronger collaboration.

“From lower energy costs to cleaner air and more resilient communities, this transition is improving lives today while securing our future. And cities are where this transition moves from words to facts”

National governments must play a critical role by integrating city-led action into national climate and energy plans, increasing investment in urban clean energy solutions and expanding access to municipal funding, as well as enabling energy decentralisation and direct power purchase agreements. In particular, expanding access to finance, supporting municipal funding mechanisms such as Johannesburg’s green bonds, and enabling cities to enter renewable energy agreements can unlock large-scale implementation.

Governments must also accelerate the transformation of energy systems by modernising grids, supporting electrification, and ensuring that clean energy is the most accessible and affordable option for households. 

“Colombia has been clear: the transition away from fossil fuels is not only necessary, it is an opportunity to build a more just and resilient future,” said Irene Vélez Torres, minister of environment and sustainable development of Colombia. “But this transformation cannot be achieved by national governments alone. Cities and regions are essential to this effort. They are where people live, where inequalities are felt most deeply, and where the impacts of climate change are already being experienced every day. That is why we must work together to accelerate this transition in a way that delivers a better future for those who matter most: people. This is about moving forward. All together.”

Stientje van Veldhoven, minister of climate policy and green growth, Kingdom of the Netherlands, added: “The Netherlands is committed to accelerating the transition away from fossil fuels as a practical pathway to secure clean, reliable and affordable energy for our societies. But this transformation cannot be delivered by national governments alone.

“Cities are essential partners: they are where innovation happens, where solutions are implemented, and where people experience the benefits of this transition in their daily lives. That is why we must work together to turn ambition into action, by supporting cities, unlocking investment, and scaling the solutions that are already working. This is how we build stronger, more resilient economies and deliver a better future for everyone.”