The demands are as diverse as the regions they are coming from, but the ultimate ask is unique: to stop burning fossil fuels and take real actions to overcome the climate crisis.
Over 7,370 websites shut down and around 3,000 companies closed their doors in support of the Global Climate Strikes on Friday.
From Jakarta to New York City, from Karachi to Amman, from Berlin to Kampala, from Istanbul to Quebec, from Guadalajara to Asuncion, in big cities and small villages, millions of people joined hands and gathered their voices in defence of the climate.
There were 40,000 people striking in France; 2,600 in Ukraine; 5,000 in South Africa; 10,000 in Turkey; 5,000 in Japan; 30,000 in Australia; 100,000 in London; 400,000 in Australia; 250,000 in New York City; and 1.4 million in Germany only.
"Today we saw a movement, made up of people from all ages and backgrounds coming together and calling for the end of coal, oil, and gas. No matter what differences we have, we are together now because we are fighting for our future," May Boeve, Executive Executive Director of 350.org said.
"September 20th was a demonstration of intent, of four million people who took time off from work or school to say that they are ready. Ready to move on and make the changes we need for a future free from fossil fuels and based in climate equity and justice. And it was only the beginning."
Friday's demonstrations mark the beginning of a global mobilisation which will span until September 27.
The climate week will surround the UN Climate Summit being held on September 23, which will gather world leaders in an attempt to accelerate the shift away from fossil fuels, to implement the Paris Agreement and meet the climate challenge.
"We strike so that in the UN meeting, when they speak, it is with our beliefs on their tongues. We strike so that when they raise their hands to vote, it is with the weight of our vision hanging from the tips of their fingers," Evan Meneses, 17, school striker from Australia said.
Britain based Christian Aid's youth and campaigns manager, Richard Baker, said: "The youth climate strikes have been nothing short of prophetic. One seemingly defiant act of protest by a 16-year-old girl in Sweden has grown into a thundering movement for change that is sweeping the globe.
"The climate strikers are pointing the way, it's now time world leaders and big business take heed and take action. This week at the crucial summit in New York we need to see countries making new pledges to cut their emissions and stronger commitments to help the poorest communities already suffering from the climate crisis."
( With inputs from IANS )