A day after youth-led global climate strikes, several hundred young activists including Greta Thunberg gathered for a climate summit at the United Nations, hitting out at older generations for doing too little to curb carbon emissions.
The UN has invited 500 young activists and entrepreneurs to take part in the meeting, the first of its kind, though some were unable to attend after being denied US visas, a point raised by the organisers.
It comes days before a climate action summit which UN chief Antonio Guterres has called to seek greater commitments from world leaders on reducing their greenhouse gas emissions in line with the Paris accord to avert runaway global warming.
The tone for today's event was set by an impassioned speech by young Argentine activist Bruno Rodriguez, 19, who led school strikes in his native country.
"The climate and ecological crisis is the political crisis of our time, it is the economic crisis of our time, and it is the cultural crisis of our time," he said, watched by Mr Guterres, who was billed as the "keynote listener."
"Many times, we hear that our generation is going to be the one in charge of dealing with the problems that current leaders have created, and we will not wait passively to become that future: the time is now for us to be leaders."
Ms Thunberg, whose protests outside Sweden's parliament last year sparked the global youth movement, spoke first but briefly, saying she wanted to give more time to the others.
"We showed we are united and young people are unstoppable," said the 16-year-old, who will also address Monday's summit.
Yesterday, masses of children skipped school to join global strikes that Ms Thunberg said were "only the beginning" of the movement.
Some four million people filled city streets around the world, organisers 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.
Strike organisers 350.org said yesterday's rallies were the start of 5,800 protests across 163 countries over the next week.
'Change is coming'
The corridors of the UN were filled today with young people in formal suits and ties, dresses, and traditional wear from their home countries, and others wearing simple t-shirts and jeans.
"When you walk around this building, you see a bunch of old, mainly men wearing suits and big ties," Yusuf Omar, 30, who is a journalist originally from Britain, told AFP. "It's great to be brought to the table (and) that we are now helping to make decisions."
"This is the change, and it's coming," added Lalita P-Junggee, a green entrepreneur from Mauritius, who turns billboards and textile waste into fashionable bags.
Beyond expressing their discontent, the day involves sessions promoting solutions, with innovators proposing their ideas to judging panels from leading global companies.
There are also workshops on digital activism, including a class on how to make videos that go viral.
A landmark UN report to be unveiled next week will warn global warming and pollution are ravaging Earth's oceans and icy regions in ways that could unleash misery on a global scale.
But Mr Guterres struck a more optimistic note today, telling the young leaders: "There is a change in momentum.
"This changing momentum was due to your initiative and to the courage, with which you have started these movements."