NEW YORK - Massive amounts of people flooded the streets of lower Manhattan on Friday for a youth-led climate strike, calling for leaders to take immediate action.

"I see beautiful nature right now. I want this to still be here. I don't want this to all be polluted," a young student said at the rally at The Battery.

The strike was part of a global movement with young people in more than 150 countries participating.

In the city, crowds gathered in Foley Square in Manhattan before marching down to Battery Park for the main rally.

Several celebrities, including Jaden and Willow Smith, were in attendance, as was 16-year-old Swedish climate activist Greta Thunberg.

"This is an emergency. Our house is on fire," Thunberg said. "And it's not just the young people's house. We all live here. It affects all of us."

People at the rally said they were advocating for their future.

"It definitely feels empowering to know that like it's not just me who feels that this is a problem," said one person at the rally.

"I want to have a future. I feel like I deserve the right to grow old and have children and grow up in a world where, you know, I'm not dying because of a bunch of people's opinions on what is and isn't, I don't know, good to invest in," said another person rallying.

Some perched in trees at The Battery, others on shoulders, to hear her throw the gauntlet at world leaders descending on the city to attend the climate action summit at the United Nations next week.

Thunberg: They have a chance to take leadership, they have a chance to actually hear us. Do you think they hear us?

Crowd: No!

Thunberg: We will make them hear us.

A number of people we talked to said it was not lost on them that they got such a picture-perfect day for a rally to save the Earth. It added a sense of urgency:

"Everyone's in this," a rallying student said. "Other people need to change so they can help the world and the world can stay here for millions and millions of years."

There was also admonishment, and hope.

"I'm just really happy that we're making history today, and people from all around the world are coming together for a common cause," an older student said.

And this isn't the end: this climate strike kicks off a week of events focused on being heard about working to save the world.