And though Thunberg, who arrived in the Big Apple two days ago after a two-week voyage on a sailboat, had little to say during the event on Friday, the other participants were visibly energized by having her among them holding a sign reading "skolstrejk för klimatet" (Swedish for "school strike for climate"), Efe news reported.
A year ago, Thunberg, then 15, began skipping school on Fridays to demonstrate outside Sweden's parliament.
The group chanted slogans such as "System change, not climate change," "Unite behind the science" and "Stop denying, the earth is dying."
Thunberg's example has been emulated by thousands of students worldwide, giving rise to the Fridays for Future movement.
One of the young people Thunberg inspired was Alexandria Villaseñor, a 14-year-old New Yorker who has been protesting outside the UN every Friday starting last December.
"Greta being here in the United States and in America will really galvanize students just because of how much of an inspiration she is," Villaseñor said Friday, thanking Thunberg for making the trip to New York.
"And the climate crisis should not have to be put on my generation's shoulders. It should have been done by world leaders and people in power. They should have chose our future over money," Villaseñor said.
Other speakers called on the international community to act immediately on the climate crisis, blasted US President Donald Trump for his reluctance to acknowledge the problem and urged an end to the use of fossil fuels.
The organisers of Friday's protest announced plans for another demonstration on Sept. 20, just ahead of the Sept. 23 UN Climate Action Summit, where Thunberg is scheduled to speak.
Thunberg refuses to fly because of the emissions associated with air travel and when the UN invited her to address the climate summit, she faced the challenge of getting to New York without flying.
Last month, the owners of the racing yacht Malizia II, which is skippered by Pierre Casiraghi - son of Monaco's Princess Caroline - and German distance sailor Boris Herrmann, offered Thunberg a ride to New York.
The carbon-free vessel, which relies on solar panels and hydro-turbines for auxiliary power and is equipped with sensors that collect data on ocean acidity, sailed from Plymouth, in southern England, on Aug 14, and reached New York on Wednesday.
In the brief news conference she held after disembarking at Manhattan's North Cove Marina, Thunberg described climate change as "the biggest crisis humanity has had to face."
"We need to stand together and take action because otherwise it might be too late. Let's not wait any longer, let's do it now," the young Swede said. "My message to all the activists: Just keep going. I know it may seem impossible at times."
( With inputs from IANS )