Alexandria Ocasio-Cortez said she was ‘inspired’ by the Global Green New Deal, a bold proposal to fight climate change announced today by the C40 group of global mayors.

To kick off their major summit this week the group, which represents more than 90 of the world’s biggest cities, voiced their backing for the plan and said it reaffirmed their “commitment to protecting the environment, strengthening our economy, and building a more equitable future by cutting emissions”.

New York congresswoman Ocasio-Cortez applauded the move, adding: “If we work to join forces globally, we will be able to defeat our greatest threat and realise our greatest opportunity.”

Q&A Which countries contribute most to the climate crisis? Show China produces the most heat-trapping pollution, followed by the US. But historically, the US has contributed more carbon dioxide to the atmosphere than any other nation. The US also has high emissions per capita, compared to other developed countries. And Americans buy products made in China, therefore supporting China's carbon footprint.

Ocasio-Cortez arrived in Copenhagen on Wednesday morning ahead of the seventh World Mayors’ Summit held by the C40 group of leading global cities, where she is scheduled to make a speech on Friday.



She immediately started posting videos of the city to her 4m Instagram followers.

Eric Garcetti, the Los Angeles mayor who is now taking over as chair of C40, told a press conference after the announcement that delivering the Global Green New Deal would be his priority.

“This will be my priority as the new chair, to deliver a Green New Deal in the face of the climate emergency and to make the 2020s the decade of human action,” he said.

“This will be the defining decade not only of our lives, but of life itself for human beings on this planet. I have no doubt that we can and will get it right, because human beings have this stubborn desire to survive.”

Jamie Margolin, Seattle-based high school senior who founded the US green pressure group Zero-Hour, called on the cities to raise their ambitions.

“The Green New Deal is not just about a specific piece of legislation or about a promise a politician makes. It’s about finally ending the fairy tale. With the Green New Deal we are calling to an end the sacrificing of everything to protect that fairytale of eternal economic growth.”



The mayors group, representing more than 90 of the world’s biggest cities, also launched a blistering attack on the failure to agree strong measures to fight the climate crisis at last month’s UN Climate Action Summit, blaming “a small number of powerful governments serving the interests of the fossil fuel industry”.

Mayor of Paris Anne Hidalgo criticised the failure of world leaders to agree on robust measures to counter the climate crisis. Photograph: Thomas Samson/AFP/Getty Images

“World leaders met in New York just last month and once again failed to agree anything close to the level of action necessary to stop the climate crisis,” the group’s chair, Anne Hidalgo, the mayor of Paris, said in a statement.

“Their ineptitude directly threatens all people around the globe as time keeps running against us.”



Mark Watts, the C40 executive director, told the Guardian that the leaders of the US, Brazil, Australia, Russia and Turkey were now “essentially representatives of the fossil fuel industry”, so it was important for “the next most powerful group of politicians”, the mayors of the biggest cities, to step up.



“It makes what we do even more important, because in the context of those really powerful nations not only holding back their own actions but blocking the whole of the United Nations, we’ve got to have momentum coming from somewhere else,” Watts said.

The conference gathers leaders from cities around the world for three days to share ideas on green urban development and how to pressure national leaders to act on the climate crisis.



The conference covers themes such as affordable housing, waste and climate migration. The city of Copenhagen, which has an ambitious plan to become carbon-neutral by 2025, is showcasing efforts such as apartments built with recycled materials and energy-efficient systems.

Greta Thunberg addresses world leaders at the start of the 2019 Climate Action Summit. Photograph: Justin Lane/EPA

As they arrive at the summit’s opening ceremony on Wednesday evening, the mayors and their staff will nonetheless have to pass a “green illusions scanner” erected by the local green pressure group Klima Aktion DK.

Protesters will also carry binoculars to show that city leaders are being watched.



“The entire framework around the C40 has the wrong approach,” said Kirsten Kværnø, one of the organisers. “They’re taking the wrong starting point: that technology and green growth is going to save us from this crisis.”



Hidalgo said ahead of the conference that she supported the disruptive protests launched this week in London, Berlin and elsewhere by the protest group Extinction Rebellion.

“We are facing a climate emergency, and a growing number of people around the world, particularly young people, are treating it as such,” she said.



“We share their concern for the future of humanity, and we must push forward with courage and ambition to change the status quo that has generated this crisis.”



As well as mayors, Watts said this year’s summit would bring together “more of the genuine national leaders of youth climate strikes than ever before”, with youth activists from 30 different countries.

Follow Guardian Cities on Twitter, Facebook and Instagram to join the discussion, catch up on our best stories or sign up for our weekly newsletter