Teenagers on the streets of Paris warned governments on Friday there would be no summer let-up in their efforts to push for stronger action on climate change, as international green campaigners called a global strike for Sept. 20.

"I should be at school, revising for my French baccalaureat - but I'd rather be here, for my future," said Jules, 17, who only wanted to give his first name.

He and five friends decided to skip school despite end-of-year exams creeping up, to participate in what is thought to have been one of the biggest global climate actions by young people yet, mobilizing hundreds of thousands.

Organizers expected strikes and demonstrations to happen in more than 1,600 places in 110 countries - from New Zealand to Syria and Venezuela. By 1900GMT, nearly 2,500 strikes had been registered on the "Fridays for Future" website, with the number likely to rise. The students are following in the footsteps of 16-year-old Greta Thunberg who has been credited with starting the movement.

Forty weeks ago, the Swedish climate activist started skipping school every Friday, to protest climate change outside Stockholm's parliament, inspiring a large global strike on March 15, in which an estimated 1.5 million young people took part.

"I think politicians around the world think the movement will fade and that people will stop striking, especially with the summer break coming up," said Laure Miro, 16, striking for the second time in Paris. "The strikes keep getting bigger, more and more people are getting involved and we are very determined. We're not going to stop here, after all this work," she said. "Greta spoke out, so we could act," she added. School strikers said they would kick-start a week of action, starting on Sept. 20 with a worldwide strike for the climate, ahead of a key summit on climate change organized by the U.N. secretary-general on Sept. 23.

Bill McKibben, a founding member of global climate campaign 350.org, said adults would join the young people by "walking out of our workplaces and homes. We hope to make it a turning point in history," he said in a statement on Friday.

UNIFYING FORCE

Thunberg — who has been nominated for a Nobel Peace Prize is urging governments to declare a climate emergency, as has happened in Britain, Scotland and Ireland, a call echoed by many on European strikes.

Thunberg told thousands of supporters gathered in Stockholm's banking district on Friday that this week's EU election should be focused on tackling climate change.

"But it isn't. Not at all," she said. "If we don't do it at the European Union level, or even on a global scale, it will be pointless," said Anthony Didelet, a 17-year-old student in Paris. "With the European elections coming up (in France), I think this is the time to make ourselves heard."

In Barcelona, more than 200 people - from school pupils to university students and families with young children

braved the rain, shouting slogans such as "Change the system, not the climate" and "No to pollution". Many waved homemade banners written in English, and the march ended outside city hall where a timer with red sand was placed to symbolize how time is running out to act on the "climate emergency" and speakers urged politicians to step up.

"I think that the job of the politicians is to really start making decisions that aren't just centered around money, and centered more around recognizing that this (Earth) is our home and it's everyone's home," Zora Schoner, 20, an American student at Barcelona's Pompeu Fabra University, told the Thomson Reuters Foundation. Her fellow student Julia Lopez Garcia, 18, from La Rioja in Spain, said there was a need to create a movement and "make it alive, and make it so that everyone feels part of it."

Schoner said she hoped climate change could be "a really uniting topic" in a divided world. "I think that if the opportunity was used correctly, it could actually... bring people together and unite a lot of groups," she added.