NEW YORK - They’re calling it the largest mobilization against climate change in the history of the planet. Hundreds of thousands of demonstrators of all ages and from around the world turned out for the massive People’s Climate March Sunday, filling the streets of midtown Manhattan with demands for global leaders take action to avert catastrophic climate change.

Crowds gathered with banners, flags and floats around Columbus Circle late Sunday morning as music and chants rang out at the start of the march. At exactly 12:58 p.m., demonstrators held a moment of silence in honor of the victims of climate change, followed by a cacophony of noise with drums, cheers and horns to sound the alarm to the crisis.

Organizers estimate that as many as 310,000 demonstrators turned out for the march, though police won’t comment, telling msnbc they don’t release crowd numbers. The crowds were so massive that by mid-afternoon, organizers said they were asking people to disperse and cut the march short by nearly ten street blocks.

“The general public does care, and here we are.” 350.org executive director May Boeve

Many of the protesters at the New York march came from far-flung countries around the globe, including China, India, Senegal, Zimbabwe, Turkey, and South Africa. Kathryn Leuch, an activist from the Philippines, said she was participating in the People’s Climate March because of what global warming could do to her homeland.

“People in the Philippines are part of the most impacted and vulnerable to climate change,” she said. If humanity keeps burning dangerous amounts of carbon, she said, the result could be more extreme weather events on par with Typhoon Haiyan, which killed thousands of thousands of people in the Philippines and the surrounding area in 2013.

Marchers from much closer by also said they had experienced the effects of climate change and pollution firsthand. A group of young environmental activists from Newark, N.J., said they had joined the march because of how industrial waste was already blighting their community.

view photo essay People's Climate March draws massive crowd Protesters from all over the U.S. and the world are converging on Manhattan to demand that global leaders take action to avert catastrophic climate change.

Following the march, activists plan to stage Flood Wall Street, a massive sit-in Monday morning to take the climate crisis to the home of the Occupy Wall Street movement. Eric Verlo, an Occupy Denver activist who came from Colorado to join the march and participate in Flood Wall Street, said the goal is to confront the Financial District with the possibility that rising sea levels could flood Lower Manhattan. The protest will occur without a permit, making arrests likely.

“We’re also hopeful that not, the authorities will get wise and figure out that they can try to minimize the message by not arresting people,” said Verlo. “Because all we want is to get the message out, and we can get the message out either way.”

The march through Manhattan, spanning roughly two miles down to 11th Avenue and 34th Street, adds to nearly 3,000 other climate events across the globe.

“Not only will it be the largest climate march that’s ever happened, but it really represents a new kind of movement that’s much more diverse,” said 350.org executive director May Boeve. “Climate change has been something of a siloed issue for a long time, but I think that’s really changed, and that’s a good thing. More and more people are seeing how climate change affects them.” Close video Largest climate change rally takes over New York City Alex Witt talks to MSNBC Reporter Ned Resnikoff who is following the People’s Climate March in New York, just one of the rallies taking place in 162 countries Sunday. Alex Witt talks to MSNBC Reporter Ned Resnikoff who is following the People’s Climate March in New York, just one of the rallies taking place in 162 countries Sunday. share tweet email Embed

The march takes place just days before the United Nations’ 2014 Climate Summit at its headquarters in Midtown Manhattan. U.N. Secretary General Ban Ki-moon said in a statement Sunday that he hoped leaders would take action and that the march’s message would be reflected at the summit.

“While marching with the people, I felt that I had become a secretary-general of the people,” he said. “There is no Plan B because we do not have a planet B. We have to work and galvanize our action.”

The Riverside Church, which has long been a fixture of social justice activism in New York, is one of the institutions participating in the march. In addition to the dozens of church members who are participating in the rally, Riverside will also host roughly 80 activists from Florida, Colorado and Texas, according to lay leader Beth Ackerman. Explaining the church’s involvement in the march, she described climate change as “the social justice issue of the day.”

“More and more people are seeing how climate change affects them.” 350.org executive director May Boeve

“Island nations who are resource poor are losing their entire homes, and we hope that the UN is going to take their plight very seriously,” she said. “And of course, they weren’t the ones who were burning all the fossil fuels that got us into the climate change problem in the first place.”

Vulnerable populations also exist a little closer to home. The climate march included a substantial contingent of New York residents who live in the Far Rockaway section of Queens, one of the places hardest hit by Hurricane Sandy. One of those marchers was Danielette Horton, a resident of one of the Far Rockaway housing projects in the path of the hurricane.

“The community was devastated. We had to walk around with flashlights because all the lights were gone and there was no food,” she said. “We had to get food from handouts. And it was the first time for people in the area, they had never experienced a storm like that.”

Without decisive action to prevent further climate change and protect Far Rockaway, she predicted that it would not be the last time that she and her neighbors experienced such a storm.

Whatever happens this week, real UN treaties will have to wait a year. Although attendees of Tuesday’s climate summit will discuss the risks of climate change and some possible remedies, the 2015 Climate Change Conference in Paris, France is where leaders are hoping to stamp out a binding agreement. In the meantime, the organizers of the People’s Climate March are hoping their rally will demonstrate that popular momentum is on the side of the ambitious action.

“What we hear when we’re meeting with elected leaders about this issue is that it’s fine that you’re meeting with us, but the general public doesn’t care about this issue,” said Boeve. The march, she said, is about saying, “No, the general public does care, and here we are.”

“The 99 percent, if you will, of people are not in power. They might not have power, they might not have money, but they have a voice,” said Ackerman. “But they won’t have a strong voice unless massive amounts of them get together.”