Change is coming whether they like it or not.

NEW YORK (AFP) — Masses of children skipped school to join a global strike against climate change that teen activist Greta Thunberg said was “only the beginning,” ahead of a UN youth summit she will participate in Saturday.

Some four million people filled city streets around the world, organizers said, in what was billed as the biggest ever protest against the threat posed to the planet by rising temperatures.

Youngsters and adults alike chanted slogans and waved placards in demonstrations that started in Asia and the Pacific, spread across Africa, Europe and Latin America, before culminating in the United States where Thunberg rallied.

“Change is coming whether they like it or not,” said Thunberg, hitting out at skeptics as she wrapped up the massive day of action in New York, where she said that 250,000 protested.

Strike organizers 350.org said Friday’s rallies were the start of 5,800 protests across 163 countries over the next week.

From Berlin to Boston, Kampala to Kiribati, Seoul to Sao Paulo, protesters brandished signs with slogans including “There is no planet B” and “Make The Earth Great Again.”

In New York’s Battery Park, tens of thousands of supporters gave Thunberg a rockstar reception, chanting her name as she called on leaders to act now to curb gas emissions.

On Saturday, she and 500 other youth environmentalists from around the world will take part in the first-ever Youth Climate Summit.

Then on Monday, UN Secretary General Antonio Guterres has convened a Climate Action Summit where more than 60 world leaders will take to the podium to present greenhouse gas emissions reduction goals.

Events began Friday in the deluge-threatened Pacific Islands of Vanuatu, the Solomons and Kiribati, where children chanted: “We are not sinking, we are fighting.”

The defiance reverberated across the globe as kids closed their textbooks in a collective call to action.

“We are the future and we deserve better,” 12-year-old Lilly Satidtanasarn, known as “Thailand’s Greta” for her campaign against plastic bags in malls, told AFP in Bangkok.

Schoolchildren rallied in India while thousands protested in the Philippines, which experts say faces threats from rising sea levels and increasingly violent storms.