Sadiq Khan was elected for a second term as Mayor of London in May 2021. He was previously an MP for Tooting, South London for 11 years and served as Shadow Secretary of State for Justice from May 2010 and Shadow Minister for London from 2013.
Mayor Khan has declared a climate emergency and described it as one of the biggest threats we face today. In response, he has set an ambition for London to be net zero by 2030. He has also committed to a Green New Deal for London and to ensuring that there is a just transition in the capital from fossil fuel intensive industries to climate solutions.
Yvonne Aki-Sawyerr OBE was Mayor of Freetown from May 2018 to February 2023 and was re-elected to serve for a second term. A finance professional with over 25 years of private sector experience in strategic planning, risk management consulting and project management, Mayor Aki-Sawyerr adopted an inclusive, data-driven approach to addressing challenges in the city. She championed the four-year Transform Freetown plan, which detailed 19 concrete targets across 11 sectors and covered issues ranging from tackling environmental degradation to facilitating the creation of jobs for youth. Annual Transform Freetown reports, which document progress made against targets, can be viewed here.
Mayor Aki-Sawyerr’s notable achievements include: the construction and operation of Freetown’s first-ever wastewater treatment plant; the digitalisation and expansion of the city’s property rate system, the creation of over 3,500 jobs for youth and women; the planting and tracking of over 800,000 trees as part of the #FreetownTheTreeTown 1 million trees target; and securing the ongoing feasibility study for the introduction of a cable car system for the city.
Mayor Aki-Sawyerr’s public sector engagement began with her work during the 2014-2015 Ebola epidemic and her subsequent role as Delivery Team Lead for the second phase of a multi-stakeholder programme to drive socio-economic recovery in Sierra Leone post-Ebola. Mayor Aki-Sawyerr was featured by Time Magazine in the Time100 Next 2021 List and by the BBC in the BBC 100 Women 2020 List. She is a Chartered Accountant with an MSc in Politics of the World Economy from the London School of Economics and a BSc Hons in Economics from Fourah Bay College. She is married with two children.
Pramono Anung Wibowo (born in 1963, in Kediri, Indonesia) is an Indonesian politician currently serving as the Governor of Jakarta since 20 February 2025. A member of the Indonesian Democratic Party of Struggle (PDI-P), he previously held the position of Cabinet Secretary from 12 August 2015 to 20 September 2024. His legislative career includes serving as a Member of the House of Representatives from 1999 to 2015, during which he was the Deputy Speaker from 2009 to 2014. Pramono holds a degree in Mining Engineering from the Bandung Institute of Technology, a Master’s in Management from Gadjah Mada University, and a Doctorate in Political Communication Science from Padjadjaran University.
Ibrahima Cissé (also known as Cissé Ibrahima Bacongo), is a lawyer, writer, teacher, and Ivoirian politician. He holds a Doctorate in Law, a Graduate Diploma in Business Law with an international option (DESS), and a Diploma of Corporate Counsel (DJCE).
Cissé was appointed Minister and Governor of the Autonomous District of Abidjan by the President of the Republic of Côte d’Ivoire, His Excellency Mr. Alassane Ouattara in December 2023.
Ibrahima Cissé began his career as a lecturer at the Unit of Training and Research (UFR) in Legal, Administrative, and Political Sciences at the Faculty of Law at the University of Cocody. He joined the firm Conseils Associés in Africa as a permanent internal consultant in March 1993.
On March 13, 2012, he was reappointed Minister of Higher Education and Scientific Research. In 2018, Ibrahima Cissé ran for and won a legislative election in the municipality of Koumassi, and was re-elected in 2023.
On August 12, 2022, by decree, President Alassane Ouattara appointed him Executive Secretary of the Rally of Houphouëtists for Democracy and Peace (RHDP).
By joining C40, the Minister Governor aims to work towards a greener future and continue promoting and supporting the leadership of governors and mayors of African cities.
To this end, he intends to act on several levels:
- Inspire climate leadership in African cities
- Support the definition and implementation of innovative climate actions that impact our communities
- Transform challenges into opportunities for green jobs
- Develop technical and financial mechanisms for Global South Cities to address the urgency of climate change
Mayor Kate Gallego is the second elected female mayor in Phoenix history, and the youngest big city mayor in the United States. She graduated from Harvard University and earned an MBA from the Wharton School of Business at the University of Pennsylvania. Before being elected to Phoenix City Council, Mayor Gallego worked on Economic Development for local utility company, Salt River Project.
Mayor Gallego has focused on three key policy areas during her time in office: diversifying the economy, strengthening infrastructure investment, and working to make Phoenix a leader in sustainability. Her record of proven results includes leading the campaign to pass Phoenix’s citywide transportation plan through 2050, which was the largest local government commitment to transportation infrastructure in the country when it passed in 2015. She has led efforts on criminal justice reform and ensuring equal pay for equal work. Mayor Gallego is passionate about building a Phoenix that works for everyone and increasing the quality of life for all Phoenicians.
Phoenix is the fifth largest city in the United States and is currently the fastest growing city in the country.
Federico Gutiérrez is serving as the Mayor of Medellín for the second time. and his recognition and popularity among the people of Medellín and many Colombians are the result of a life dedicated to public service.
Politics as a way to find solutions to social problems and public service as a tool to help people has been Mayor Gutiérrez’s life project. He has never stopped walking the streets and studying the realities of the city and the country, listening to its citizens, gathering proposals from various social sectors, and thinking about how to contribute to the transformations demanded by today’s Colombia. He wants to continue working for Colombia and its regions to seek peace for families and opportunities for progress for everyone through a governance model based on citizen trust, institutional solidity, and teamwork among the public sector, private sector, academia, and civil society, without class antagonisms or hatred.
Nicholas Reece is the current Lord Mayor of Melbourne, elected as the 105th Lord Mayor in July 2024. He has served as a City Councillor since 2016 and as Deputy Lord Mayor from 2020 to 2024. Reece has a diverse background, having worked as a lawyer, journalist, political strategist, and public servant. He was previously a senior adviser to Prime Ministers Julia Gillard and Kevin Rudd, and Premiers Steve Bracks and John Brumby.
Reece has played a significant role in Melbourne’s post-pandemic recovery, focusing on city-shaping projects such as the Greenline riverfront transformation and the redevelopment of the Queen Victoria Market. He is also deeply involved in social causes, including the Movember Foundation and The Big Issue, where he holds leadership roles. Known for his hands-on approach, Reece is committed to improving the quality of life for all Melburnians through sustainable urban development and community engagement.
H.E. Hon. Sakaja Arthur Johnson was elected the Governor of Nairobi City County, Kenya, in August 2022. Governor Johnson is working to realise a vision of Nairobi as the Green City in the Sun, a nickname derived from the city’s foliage and warm climate.
Johnson’s commitment is to put the city at the frontline for the implementation of the Climate Action Plan (2020-2050) with the support of C40, and focusing on developing a roadmap to get Nairobi to net zero, creating green jobs, and strengthening local resilience.
Johnson previously served as Senator of Nairobi. During his tenure in Parliament, he served as Chairman of the Standing Committee on Labour and Social Welfare and as Vice Chairman of the Standing Committee on National Security, Defence and Foreign Relations. He also served as the chairperson of the Kenya Young Parliamentarians Association.
Johnson has been nominated among the top 100 Future Leaders: The World’s Most Influential Young People in Government (2018) by Apolitica and awarded Change Maker of the year 2016 at the African Achievers Award, in recognition of his leadership skills and youth empowerment in Kenya. Johnson was elected to represent the 13 C40 cities in Africa.
Giuseppe Sala is the Mayor of Milan. He is C40 Vice Chair for Europe, and chairs the Mayoral Task Force on a Green and Just Recovery.
Throughout his professional life, he has held positions of responsibility in both the private and public sectors, gaining important managerial experience.
He was the Government Commissioner and CEO of the World Expo held in Milan in 2015.
His love for Milan and his willingness to make it a more sustainable, more international and fairer city led him to commit himself to politics.
He was elected Mayor in June 2016 and re-elected in October 2021.
Giuseppe Sala holds a Degree in Economics and Business Administration from Bocconi University.
He is the author of four books, including Milano e il Secolo delle Città (Milan and the Century of Cities) and Lettere dalle città del futuro: Costruiamo oggi il mondo di domani (Letters from the cities of the future: Let’s build today the world of tomorrow).
Oh, who began an unprecedented fourth term as mayor of Seoul in July 2022, is well-known for his environmental leadership. He co-founded the Korea Federation for Environmental Movements and, as a lawyer, helped to establish the right to sunlight for the first time in South Korea’s history.
As mayor, Oh has prioritised inclusive climate action to reach net-zero emissions by 2050, protect the safety of residents from the effects of climate change and improve equity. Among other measures, Oh has championed the Seoul Energy Welfare Civic Fund, which supports energy efficiency improvements among low-income households and other vulnerable populations, and connected young people hit hard by the COVID-19 pandemic to new climate and environmental jobs.
Mayor Oh is committed to tackling air pollution, a major public health threat. In 2007, he developed the Clean Seoul 2010 initiative and in 2022, updated it as part of the Cleaner Seoul 2030, which includes various policy actions to cut air pollution emissions by 50% by 2030. Also high on Oh’s agenda is addressing emissions from waste. Under his leadership, Seoul is working towards a Zero Waste Seoul and striving to increase the plastic recycling rate to 80% by 2026. These efforts led to Seoul’s recycling earning the highest scores on the Global Power City Index ranked by the Mori Memorial Foundation in 2022.
Eduardo Pimentel has been the Mayor of Curitiba, Brazil, since January 1st, 2025, after successfully serving two consecutive terms as Vice Mayor from 2017 to 2024. With a solid background in public administration and business strategy, Mayor Pimentel has placed sustainable development and green innovation at the centre of Curitiba’s governance.
Under his leadership, the city took a historic step by implementing the landmark Climate Law in 2025, legally embedding sustainable targets into the municipal framework. He is actively spearheading major climate adaptation and urban infrastructure projects designed to prevent flooding, alongside a comprehensive tree-planting program that expands the city’s parks and vital green spaces.
A fierce advocate for zero-emission transit, Mayor Pimentel is accelerating the transition towards a carbon-neutral future. Through the Laneshift program, he has rapidly scaled up the electrification of the city’s fleet and successfully launched the first public EV charging station in Southern Brazil.
As a member of the C40 Steering Committee representing Latin America, Mayor Pimentel is a powerful voice for nature-based solutions, citizen-led climate action, and regional cooperation. He is deeply committed to ensuring Curitiba shares its pioneering urban solutions with the C40 network while advocating for bold city diplomacy on the global stage.
Eirik Lae Solberg represents the Conservative Party has been the Governing Mayor of Oslo since fall 2023. Governing Mayor Solberg is strongly committed to Oslo’s adopted climate targets of 95% reduction in direct emissions by 2030, while ensuring that the city preserves nature and is resilient. International cooperation is essential in achieving this target.
Governing Mayor Solberg has an education in economics, political science, and history. Prior to becoming Governing Mayor, Solberg’s career has been dedicated to leading positions in local and national politics and in the private sector.
As a member of the C40 Steering Committee, representing the innovator cities, Governing Mayor Solberg will be a strong voice for using climate governance tools such as climate budgeting and public procurement to accelerate climate action. Oslo is committed to sharing solutions with other C40 cities and to advocating for city leadership at national and international levels.
Mr Tse Chin-wan is the Secretary for Environment and Ecology of Hong Kong, China. Mr Tse joined the former Environmental Protection Agency of Hong Kong in 1985, which was subsequently reorganised in 1986 to become the current Environmental Protection Department (EPD). Throughout his service with EPD, he took up a wide range of duties at professional and senior managerial levels. He was appointed as a Deputy Director of Environmental Protection in 2013 and subsequently as the Under Secretary for the Environment in August 2017.
Mr Tse possesses a broad spectrum of experience in various areas of environmental protection, including law enforcement, computer modelling, environmental impact assessment and cross-boundary cooperation with the Mainland. During his tenure as the Under Secretary for the Environment, he helped spearhead the formulation of policies on air quality, waste management, climate actions and conservation.
Sisse Marie Welling (1986) is Lord Mayor of Copenhagen since January 2026, elected as a representative of the Green Left (Socialistisk Folkeparti). She is the first non–Social Democrat to hold the position in more than 100 years, supported by a broad coalition of parties.
As vice-chair of the C40 Steering Committee, the Lord Mayor will be a strong voice for sustainable urban development with a focus on sustainable and affordable housing and urban nature – all aimed at supporting and fostering a liveable, affordable, and healthy city. A city that thrives with green spaces, harbour baths, and strong everyday conditions for residents, not at least children. In Copenhagen, climate action is integrated across sectors – from how people move around the city and how homes are heated, to how neighbourhoods are planned and how the city adapts to changing weather.
Lord Mayor Welling was elected to the Copenhagen City Council (Borgerrepræsentationen) at the age of 23, and has been active in city politics for more than 15 years. Before becoming Lord Mayor, she served as Mayor of Health and Care from 2018 to 2025. She became politically active at 14 in Green Left Youth and holds a Master’s degree in history from the University of Copenhagen. She lives on Amager in Copenhagen with her husband, Bo, and their two children.
Mayor Michelle Wu is working to make Boston a home for everyone.
From climate resiliency and transportation, to public health and community safety, Mayor Wu has established Boston as a global leader in delivering solutions to the biggest challenges families are facing.
She has divested City funds from fossil fuels and ended their use in all new City construction and major renovations; saved residents and businesses more than $230 million in energy costs through Boston’s Community Choice Electricity Program; secured funding for thousands of new jobs to protect Boston’s coastline; and doubled the number of trees planted on Boston’s streets every year.
Mayor Wu has boosted public transit ridership in the city through fare-free Boston bus lines; installed more speed humps to protect pedestrians and neighbors on residential streets in the last two years than in the previous six combined; secured a board seat granting Boston a voice in governing the MBTA; and deployed new technology to optimize traffic signals and reduce congestion on Boston’s roads.
Building on the success of her BPS Sundays Pilot program, Mayor Wu worked to make nine of Boston’s leading museums and cultural institutions free to all school-aged children in the city. As a Boston Public Schools mom, she has expanded early college and career programs to more high school students than ever before; invested in the District’s first long-term vision for facilities informed by clear data and community standards; and delivered more resources for academics, arts, and student athletics across our neighborhoods.
Mayor Wu’s administration has cut the ribbon on 20 new or newly-renovated public parks; supported more than 90 new small businesses in revitalizing formerly vacant neighborhood retail spaces, creating more than 800 new jobs; filled more than 18,000 potholes; and helped nearly 700 families become first-time homeowners through City of Boston programs.
Mayor Wu is a graduate of Harvard College and Harvard Law School. She began her career in public service interning at City Hall for Mayor Tom Menino and is an alumna of the Rappaport Fellows Program in Law and Public Policy. Mayor Wu lives in Roslindale with her husband Conor and their three children, Blaise, Cass, and Mira.