As mayors of many of the world’s great cities, and on behalf of the hundreds of millions of citizens that we represent, we urge you –– G20 Heads of State –– to deliver on your commitments to tackle climate change, one of the world’s most pressing issues.

Given the US intention to withdraw from the Paris Agreement, the resolve of the other 19 leaders at the upcoming G20 Summit to safeguard the future of our planet is more important than ever. Local leaders around the world stand together with you, redoubling our commitment to bold action on climate change, working with business leaders and citizens worldwide. We are inspired by the courage of more than 300 Climate Mayors from cities across the United States who have committed in the past weeks to adopt, honor and uphold the Paris Agreement. Hundreds of US cities, universities, and businesses have declared “We Are Still In” and committed to pursue ambitious climate goals, and to ensure that the US remains a global leader in reducing emissions. This group is now working on the creation of “America’s pledge”, an unprecedented effort to aggregate carbon reductions by cities, regions and businesses to ensure that the US achieves its Paris Agreement pledge.

To deliver on the goals of the Paris Agreement requires unprecedented action: urgent reforms are needed in energy, transport, food and waste – driving investment in low carbon economies that will create jobs and improve public health. Research by C40 Cities demonstrates that major progress towards these goals needs to be underway by 2020, by which time global emissions need to have peaked.

In our cities, we are already implementing the policies and projects needed to deliver on the ambition of the Paris Agreement. As mayors, we are committing to bold emission reductions plans, tackling air pollution and investing in sustainable infrastructure that makes our cities resilient to the effects of climate change. We are taking these measures because creating smart cities offers unprecedented opportunities. Research by New Climate Economy revealed that creating compact and connected cities, built around mass public transport would save more than $3 trillion in infrastructure investments over the next 15 years. These cities will also be more economically dynamic, healthier, equitable and have lower emissions.

We must all work together to save our planet. As cities roll out fleets of electric busses and our citizens choose to leave their polluting cars for electric vehicles, nations must speed up the process of ensuring 100% of electricity is produced from renewable sources. As mayors and businesses bring forward plans for sustainable infrastructure in our cities, national governments should ensure that financing is available for cities from international climate funds and development banks. As autonomous vehicles arrive in our cities, we must work together to create a regulatory system that ensures this shift will help cut emissions rather than add to them.

You have the privilege of leadership at a unique moment in history to help realize the potential of the Paris Agreement. The cities of the world and their citizens have a shared vision for a just and sustainable future –– one that will make our communities cleaner, healthier, happier and more prosperous. Together with business leaders we have already decided on a climate-safe future of opportunity, optimism and innovation –– there is no alternative.

As C40 mayors we will continue to lead on climate action in the most important cities of the world, standing for our people, the planet and global prosperity. Today, we seek to strengthen a pragmatic and positive alliance with you, in the service of our citizens. We look forward to working with you. Don’t miss this opportunity to deliver new hope for tomorrow.


Anne Hidalgo, Mayor of Paris and Chair of C40

Ahmed Aboutaleb, Mayor of Rotterdam

Elisabeth Ackermann, President of the Executive Council of the Canton of Basel-Stadt

Steve Adler, Mayor of Austin

Wasim Akhtar, Mayor of Karachi

Muriel Bowser, Mayor of Washington D.C.

Manuela Carmena, Mayor of Madrid

Herbert Constantine M. Bautista, Mayor of Quezon City

Ada Colau, Mayor of Barcelona

Denis Coderre, Mayor of Montréal

Marcelo Crivella, Mayor of Rio de Janeiro

Robert Doyle, Lord Mayor of Melbourne

Rahm Emanuel, Mayor of Chicago

Helen Fernandez, Mayor of Caracas

Phil Goff, Mayor of Auckland

Rafael Greca, Mayor of Curitiba

Hanna Gronkiewicz-Waltz, Mayor of Warsaw

Fumiko Hayashi, Mayor of Yokohama

Frank Jensen, Lord Mayor of Copenhagen

Raymond Johansen, Governing Mayor of Oslo

Georgios Kaminis, Mayor of Athens

Mohammad Sayeed Khokon, Mayor of Dhaka South

Yuriko Koike, Governor of Tokyo

Eberhard van der Laan, Mayor of Amsterdam

Horacio Rodríguez Larreta, Mayor of Buenos Aires

Ed Lee, Mayor of San Francisco

Patricia de Lille, Mayor of Cape Town

Miguel Ángel Mancera, Mayor of Mexico City

Clover Moore, Lord Mayor of Sydney

Michael Müller, Mayor of Berlin

Ed Murray, Mayor of Seattle

Antônio Carlos Peixoto de Magalhães Neto, Mayor of Salvador

Claudio Orrego, Governor of Santiago

Enrique Peñalosa, Mayor of Bogotá

Mauricio Rodas, Mayor of Quito

Gregor Robertson, Mayor of Vancouver

Giuseppe Sala, Mayor of Milan

Yousef Al Shawarbeh, Mayor of Amman

Mohammed Adjei Sowah, Mayor of Accra

John Tory, Mayor of Toronto

Karin Wanngård, Mayor of Stockholm

Martin J. Walsh, Mayor of Boston

Ted Wheeler, Mayor of Portland

Kam Sing Wong, Secretary for the Environment of Hong Kong Special Administrative Region Government

Park Won Soon, Mayor of Seoul

Prof. Dr. Eckart Würzner, Lord Mayor of Heidelberg

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