- I'm here because my whole generation's life depends on it. We have to fight and have no time to lose - we are tired of waiting, says Jamie Margolin, 17, from Seattle.

She is one of the US climate activists who spoke before the Congress in Washington DC with Greta Thunberg this week.

- It's been great to meet Greta. She is such a powerful voice and it feels good to have her solidarity for the fight in the US. Having her next to me in the congress made me feel less alone, says Margolin.

"No planet B"

Almost all young people have their own placards that they raise in the air. The poster carries messages such as "There is no planet B" and "Don't burn our future". In a megaphone, the question is asked: "what do we want?". One speaker answers "climate justice!"

School classes flocked in clusters to the park, where the atmosphere was raised by cries and music from speakers. From the park, participants continued on a two-mile march toward Battery Park on Manhattan's southern promontory.

The streets have been closed to all traffic due to the tens of thousands of protesters.

Elected the school

Saya, 15, from New Jersey has chosen not to go to school today to take part in the demonstration instead.

- We want to raise awareness of the climate crisis, and want the government to act. This is especially important now that the UN Climate Summit is approaching. They need to know that we young people want to see a change.

TT: What did Greta mean to you?

- She really is an icon. Greta has become the front figure for the entire movement and stepped forward when no one else did. She was the stone thrown into the pond - we are the rings on the water, says Saya.

The heat has risen in the morning, the weather game service expects it to be around 27 degrees during the day and many had prepared with caps and water bottles.

The protest is held just hours before the UN Climate Summit begins in New York.