—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.

'Safe future'

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.

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.

About 200 marched in Ghana's capital Accra, where some 44 percent of the country's population has not heard of climate change, according to a study by Afrobarometer.

"Developing countries like Ghana are the most affected. We don't have the resources to adapt to climate change," said 26-year-old protest organizer Ellen Lindsey Awuku.

In Slovakia, five-year-old Teo asked a crowd of 500 "not to cut down forests, and reduce garbage production, and not to use so many petrol-fuelled cars."

'Day of the Dead'

German Chancellor Angela Merkel used Friday to pledge at least 100 billion euros by 2030 to tackle emissions in the energy and industrial sectors, boost zero tailpipe emission electric vehicles, and get passengers out of planes and onto trains.

Organizers said more than 300,000 children, parents and supporters rallied in Australia alone.

Australia has been struck in recent years by droughts, more intense bushfires, devastating floods and the blanching of the Great Barrier Reef -- phenomena experts have blamed on a changing climate.

The protests also highlighted resistance from climate change skeptics.

Businesses also backed the protests.

Amazon chief Jeff Bezos pledged Thursday to make the US tech giant carbon neutral by 2040 and encouraged other firms to do likewise.

"My main objective is to make as much noise as I can, and to do as much as I can to support as many actors involved in this as I can, especially in relationship with the youth," he said. —AFP