Meet the co-chairs

In their roles as elected co-chairs, Mayor Aki-Sawyerr and Mayor Khan bring a diversity of perspectives to inform C40’s direction as a network of global mayors. This is crucial to effectively address the distinctive challenges that cities encounter due to their diverse social, political, and economic contexts, as well as the unique climate risks they confront.

Click below to learn about their history as mayors:

C40 Co-Chair and Mayor of Freetown, Sierra Leone

Yvonne Aki-Sawyerr OBE was Mayor of Freetown from May 2018 to February 2023 and was recently 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.

C40 Co-Chair and Mayor of London, United Kingdom
Mayor Sadiq Khan

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.

Co-chair priorities

Mayor Khan, who was first elected C40 chair in 2021, has consistently prioritised support for cities in the Global South, which are often most acutely affected by the climate crisis. As chair, he has overseen:

  • Two-thirds of the C40 budget being dedicated to accelerating climate action in low and middle-income countries.
  • Expanded C40’s air quality work, engaging more cities in low and middle-income countries, including the launch of Breathe Cities, a US$ 30 million clean air partnership between Bloomberg Philanthropies, the Clean Air Fund, and C40 Cities.
  • Launched C40’s Inclusive Climate Action Fund, which provides resources to cities to pilot and drive forward fair and inclusive climate action.
  • At the C40 World Mayors Summit in Buenos Aires, united C40 mayors to drive the creation of 50 million good, green jobs by 2030.

Mayor Aki-Sawyerr, who was elected C40 Co-Chair in November 2023, has been a vocal supporter of the Global Green New Deal and a keen advocate of youth engagement to advance climate action in cities.

As co-chair, Mayor Aki-Sawyerr is committed to:

  • Advancing multilateral action, ensuring that all levels of government work together to accelerate climate action and increase financing for it, particularly in low and middle-income countries.
  • Expanding the influence of city leaders beyond the C40 network by providing tools and resources to smaller cities.
  • Actively engaging youth for a more sustainable future.

Role history

The C40 co-chairs elevate climate ambitions around the world and highlight the importance of cities in tackling the climate crisis.

To champion inclusive global leadership in climate action, in 2023, C40 announced its new co-chair model, which requires one mayor each from the Global North and South sits at the core of C40’s leadership. The model aims to ensure the unique challenges cities encounter due to their diverse social, political, and economic contexts, as well as the varied climate risks they confront, are central to C40’s decision-making.

Prior to this, the role of C40 chair was a rotating position held by one mayor at a time. Current and past C40 chairs include:

  • Yvonne Aki-Sawyerr, Mayor of Freetown (2023–present)
  • Sadiq Khan, Mayor of London (2021–present; now co-chair)
  • Eric Garcetti, Mayor of Los Angeles (2019–2021)
  • Anne Hidalgo, Mayor of Paris (2016–2019)
  • Eduardo Paes, Mayor of Rio de Janeiro (2013–2016)
  • Michael R. Bloomberg, Mayor of New York City (2010–2013)
  • David Miller, Mayor of Toronto (2008–2010)
  • Ken Livingstone, Mayor of London (2005–2008)