Schoolchildren who gathered in Ljubljana's city centre were also joined by some adults, who brought their pre-school children to the rally, which started at 11:55 AM to indicate that is high time for action.
Protests were also held in Maribor, Koper, Novo Mesto, Kamnik, Ormož, Slovenske Konjice and Ravne na Koroškem.
Holding the banners saying "We've got no planet B", "You were allowed to dream, we will be living a nightmare", "Climate change is not cool", the protesters in Ljubljana gathered in Congress Square and then chanting and playing music moved around the city centre.
"Thousands of people understand we cannot go on like this. Thousands understand that we cannot live on a desolate planet," said Atila Urbančič of the Youth for Climate Justice movement, which organised the event.
"A change must come from us, youth, because we can no longer rely on the older generation," said activist Reja Debevec, who discussed the issue of climate change with MEPs in Strasbourg this week but was disappointed by the talks.
One of the youngest activist of the movement, Voranc Bricelj, said that young people should make concrete changes in their lives, use public transport more, eat less meat and stop using disposable plastic.
"When they (adults) see we mean it, they will follow suit – parents, teachers and other adults. Thus we'll be able to have several good things that cannot be replaced with money," he said.
Author Andrej Rozman – Roza addressed the rally as a representative of adults. He said that despite enormous technological progress, each new generation was more endangered. "You were born into a world of fraud, which is being justified by all sorts of stories and even laws. Money has become the biggest fraud and it has gone wild," he said.
The event was also supported by climate change expert Lučka Kajfež Bogataj, who attended an international conference in Maribor today. "Finally, the generation that will be most affected by our actions is raising its voice," she said, welcoming the movement.
But she believes one protest will not be enough. "Their success will depend on how persistent they will be and how numerous. A critical mass of the people who want something is very important," she told the STA.
After touring the Ljubljana centre with the protesters, representatives of Youth for Climate Justice presented their demands in person to Prime Minister Marjan Šarec and parliamentary Speaker Dejan Židan.
Their demands include green national budget reform, closure of the Šoštanj coal-fired plant and Velenje coal mine by 2030, and reducing carbon emissions in traffic to by 40% by 2040.
They called for eco-friendly development, new quality jobs, a shift to plant-based foods, and measures to stimulate community-owned power stations, housing co-operatives, community gardens and self-mobility.
"I must say the government is already doing a lot of that, the Ministry of the Environment and Spatial Planning has set out to do that," Šarec told them, inviting the youth "to help so that the measures are taken".
"We're glad you have taken action, warned of the issues and I believe words will be followed up by actions," said Šarec, who met the youth joined by the nominee for the new environment minister, Simon Zajc.
The protest has been supported by the Environment Ministry and the teachers' trade union SVIZ. Schools have indicated they will excuse the absence of student protesters from class.
The Global Climate Strike For Future is being held in more than 1,650 towns in more than 100 countries.