In Pictures and Video: What 'Biggest Day of Climate Action in Planetary History' Looks Like as Over 4 Million Strike Worldwide

Check back for more additions and updates as the #ClimateStrike continues on Friday...

Kicking off what organizers say will be the largest mass climate demonstration in history, millions of young people and their adult allies flooded the streets around the world Friday to take part in the Global Climate Strike and pressure world leaders to confront the ecological crisis with bold and urgent action.

According to 350.org, over 4 million people took part in the collective demonstrations worldwide.

"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," said May Boeve, executive director of 350.org, in a statement.  "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."

An estimated 400,000 people gathered in Australia alone as hundreds of thousands of others rallied across India, Germany, Austria, Indonesia, Kenya, Pakistan, the U.K., and other nations.

"We have no choice but to act when the alternative is to sit and watch our world burn. We have no choice but to act when the alternative is extinction."
—Vic Barrett

"We're here to reclaim our right to live, our right to breathe, our right to exist," said youth climate activist Aman Sharma, who gathered with thousands in Dehli.

Demonstrations are expected to take place in over 130 nations on Friday, with more than 800 strikes planned in the United States. "I think it's pretty clear this will be the biggest day of climate action in planetary history," said 350.org founder Bill McKibben on Friday as images and videos began to pour in on social media.

The strikes, led by youth climate activists, have drawn enthusiastic support from diverse segments of society, including teachers, scientists, tech workers, labor unions, and lawmakers.

Vic Barrett, a 20-year-old plaintiff in the Juliana v. United States climate lawsuit against the American government, wrote in an op-ed for The Guardian Friday that he is taking part in the Global Climate Strike because "this decade is our last chance to stop the destruction of our people and our planet."

"We have no choice but to act when the alternative is to sit and watch our world burn," wrote Barrett. "We have no choice but to act when the alternative is extinction."

On social media, #ClimateStrike photos and videos were flooding platforms like Twitter with an on-the-ground look from cities and countries from around the world.

[See videos here.]

Freiburg, Germany:

Sydney, Australia:

Tokyo, Japan:

Nariño, Colombia:

Quezon City, Philippines:

Paris, France:

Lahore, Pakistan:

Dublin, Ireland:

New Delhi, India:

Woerdern, Austria:

Funafuti, Tuvalu:

São Paulo, Brazil:

Cape Town, South Africa:

New York City:

San Francisco, California:

Philadelphia, Pennsylvania:

London, England:

Stratford-Upon-Avon, England:

Katmandou, Nepal:

Ceará State, Brazil:

Antarctica:

And in photos from around the world, the size of the demonstrations and the passion of those striking was palpable.

In Germany:

Baden-Wuerttemberg, Freiburg: According to police, more than 20,000 people are standing on the square of the old synagogue and demonstrating. The demonstrators follow the call of the movement Fridays for Future and want to fight for more climate protection. They want to support the calls for strikes and protests all over the world. (Photo: Patrick Seeger/dpa/Getty Images)

Participants in the Fridays For Future movement protest during a nationwide climate change action day in on September 20, 2019 in Frankfurt, Germany. (Photo: Thomas Lohnes/Getty Images)

In Indonesia:

 A group of Indonesians hold placards as they take part in a global climate change campaign in Surabaya on September 20, 2019. (Photo: Juni Kriswanto/AFP/Getty Images)

In Kenya:

Environmental activists march carrying placards as they take part in a protest calling for action on climate change, in Nairobi on September 20, 2019. (Photo: Simon Maina/AFP/Getty Images)

Children across Asia and the Pacific kicked off what are set to be the largest global climate protests in history on September 20, 2019, demanding adults act now to stop environmental disaster. (Photo: Simon Maina/AFP/Getty Images)

In India:

College students hold posters while participating in a 'Fridays for Future' climate strike to protest against governments' inaction towards climate breakdown and environmental pollution in Mumbai on September 20, 2019. (Photo by Indranil Mukherjee/AFP/Getty Images) 

In Scotland:

 campaigners protest during a climate change action day on September 20, 2019 in Edinburgh, Scotland. Protests are taking place today worldwide, with campaigners demanding that governments and corporations take steps towards lowering CO2 emissions and combating the warming of the Earth's temperatures. (Photo by Jeff J Mitchell/Getty Images)

In Turkey:

Thousands of Turkish students, holding banners and posters take part in the global climate strike held to draw the attention of global climate change, on September 20, 2019 in Ankara, Turkey. (Photo: Esra Hacioglu/Anadolu Agency/Getty Images) 

In England:

Environmental activists rally during the UK Student Climate Network's Global Climate Strike protest action in central London, on September 20, 2019. - Millions of people are taking to the streets across the world in what could be the largest climate protest in history. (Photo: Ben STANSALL/AFP/Getty Images) 

Check back for more additions and updates as the #ClimateStrike continues on Friday...

[Top photo: Thousands of demonstrators gather at the Jungfernstieg in Hamburg. (Photo: Axel Heimken/Picture Alliance via Getty Images)]