Greta Thunberg was among four young climate activists to criticise the elites gathered at the World Economic Forum for not doing enough to deal with the climate emergency and warned them time was running out.
At a panel in the Swiss ski resort of Davos, the four said they hoped their generation had found its voice and can work with those in power to bring about the necessary change to limit climate change.
Yet Greta said not enough has been done.
"We need to start listening to the science, and treat this crisis with the importance it deserves," said the 17-year-old, just as US President Donald Trump was arriving in Davos and was due to give a speech.
Climate activist Greta Thunberg has told the world's political and business leaders that the movement sparked by her school strike is only the beginning in the fight against global warming, and said much more has to be done.
Mr Trump has pulled the US out of the Paris accord to limit climate change and has traded barbs with Greta on social media.
"Without treating it as a real crisis we cannot solve it," Greta said.
The Swedish teenager came to fame by staging a regular strike at her school, sparking a global movement that eventually earned her 'Time' magazine's 2019 Person of the Year award.
She said that people are more aware about climate issues now.
"It feels like the climate and environment is a hot topic now, thanks to young people pushing," the campaigner said.
Speaking in the afternoon, she brushed aside Mr Trump's announcement that the US would join the economic forum's initiative to plant one trillion trees across the globe to help capture carbon dioxide from Earth's atmosphere.
"Planting trees is good of course, but it's nowhere near enough.
"It cannot replace mitigation," she added, referring to efforts to drastically cut emissions in the near term.
Greta accused leaders of "cheating and fiddling around with numbers" with talk of cutting emissions to 'net zero' - that is, emitting no more carbon than is absorbed by the planet or technical means - by 2050.
While there has been widespread criticism both inside and outside the United States over Mr Trump's decision to pull the US out of the 2015 Paris climate accord, Greta said the rest of the world, too, was effectively missing the targets set down in that agreement.
She dismissed the notion that climate change is a partisan issue, insisting that "this isn't about right or left".
Responding to those who have accused her of doom-mongering, she said her message was simply based on scientific facts, not irrational fears.
"My generation will not give up without a fight," she said.
The others that were on the panel were just as forceful and passionate about the effects of global warming and how they, as young people, need to play a central role in raising awareness and insist on change.
"The older generation has a lot of experience, but we have ideas, we have energy, and we have solutions," said Natasha Wang Mwansa, an 18-year-old activist from Zambia who campaigns for girls' and women's rights.
Salvador Gomez-Colon, who raised funds and awareness after Hurricane Maria devastated his native Puerto Rico in 2017, said young activists are doing more than just talking.
"We're not waiting five, 10, 20 years to take the action we want to see," he said.
"We're not the future of the world, we're the present, we're acting now. We're not waiting any longer."
Greta said the time for action was now, that being at the top of the agenda meant nothing if the world doesn't get to grips with the climate emergency.
"I am not the person who can complain about not being heard. I'm being heard all the time," she said.
"But in general the science and the voice of young people is not in the centre of the conversation."
Autumn Peltier, the chief water commissioner for the Anishinabek Nation of indigenous people in Canada, said plaudits are not what they are looking for at the World Economic Forum.
"I don't want your awards. If you are going to award me, award me with helping to find solutions and helping to make change," said the 15-year-old.