Global protests against climate change in up to 5,000 cities, towns and villages have drawn huge crowds demanding politicians prioritise green issues.
In New York, 16-year-old environmental activist Greta Thunberg spoke at a rally as more than a quarter of a million people turned out to protest against government inaction on climate change.
“Change is coming whether they like it or not,” she said.
“We will do everything in our power to stop this crisis from getting worse, even if it means skipping school or work, because this is more important,” she said, addressing hundreds of fellow school-age protesters.
“We demand a safe future. Is that really to much to ask?”
Before addressing the crowds, the teenage environmental activist told reporters in New York that she hoped Friday's massive worldwide climate strikes would mark a turning point in persuading leaders to take decisive action on global warming.
The 16-year-old described the numbers of people who took to the streets as "unbelievable".
"You see the pictures of all these people. You can't believe what you are seeing," she said during an interview, as thousands of protesters started marching in the US financial capital.
"This is not just because of me," said the Swede, who has spurred teenagers and students around the world, mainly Europe, to strike from school every Friday under the rallying cry "Fridays for future."
"This is because thousands of local organisers who have spent I don't know how many hours. They worked very hard. I'm eternally grateful for what they are doing.
"I hope this will be another social tipping point that we show how many people are engaged, how many people are putting pressure on leaders, especially before this UN climate action summit," she added, referring to Monday's carbon emissions meeting.
The UN summit on Monday will bring together world leaders to discuss climate change mitigation strategies, such as transitioning to renewable energy sources from fossil fuels.
Thousands of schoolchildren as young as eight years old in London walked towards Britain's parliament, just one of 400 marches in the UK alone.
Speaking to The National, a group of university students said the pressing climate issue forced them to attend a protest for the first time.
"We’re hoping to show solidarity, that we care, and we want to change. There is value behind the numbers. The more people that show up… that is where we can make a difference and change the system," said Anais, a 20-year-old student at Imperial College London.
Teenagers at the London march said they felt "so pessimistic" about the future and hoped for a "sustainable future". Parents with young toddlers and the elderly were also among the vocal crowd, many of whom took musical instruments to drum up noise.
Earlier on Friday, more than 300,000 people turned up on the streets of Australian cities on Friday in climate change rallies, the biggest protest seen in the country since the Iraq War.
Organisers School Strike 4 Climate said in a statement 265,000 protesters turned out at demonstrations in seven Australian cities alone. The largest crowd was an estimated 100,000 in Melbourne and 80,000 in Sydney.
Protests in Melbourne and Sydney kicked off a day of global student strikes sweeping the world on Friday.
People took to the streets in Dhaka, Bangladesh, on Friday morning urging government action. Low-lying Bangladesh is one of the most vulnerable countries at risk from rising sea levels.
In neighbouring India, schoolchildren marched outside government buildings while in Taiwan, students and teachers gathered in the capital, Taipei, to launch a petition called “Fridays for the future”, echoing a call sparked by teenage climate activist Greta Thunberg.
Some held signs which read "it’s getting hot in here" and "don’t drop it like it’s hot" - a reference to popular songs.
Climate strikes spread as far as the Solomon Islands in the Pacific Ocean, where schoolchildren rallied on the beach waving banners.
No protests were authorised in China, the world’s biggest source of greenhouse gas emissions, but Zheng Xiaowen of the China Youth Climate Action Network said Chinese youth would take action one way or another.
"Chinese youth have their own methods," she said.
"We also pay attention the climate and we are also thinking deeply, interacting, taking action, and so many people are very conscientious on this issue."
In Africa, strikes are currently taking place in Kenya’s capital Nairobi, and across Ghana and Uganda.
Europe followed, with schoolchildren descending in Paris, Madrid, Berlin and Turin as well as other protests seen in provincial towns as well as major cities.
Turin is one of the most polluted cities in Europe despite the country’s greenhouse gas emissions falling over the last ten years. Italy was criticised this year by the European Climate Foundation for failing to provide an adequate plan to further reduce emissions and dependency on fossil fuels, though activists say they are optimistic that the new left-leaning coalition could prioritise climate policy.
German Chancellor Angela Merkel and her coalition partners in government agreed a watershed moment of climate policy Friday with the introduction of a price on carbon emissions in the transport and heating sector to ensure the country reaches its emissions reduction goals. Germany says all proceeds from co2 pricing will be reinvested in climate protection or given back to citizens in the form of financial relief.
The UN summit on Monday will bring together world leaders to discuss climate change mitigation strategies, such as transitioning to renewable energy sources from fossil fuels.
