DAVOS, Switzerland — Greta Thunberg, the 17-year-old Swedish climate activist, spent this week inside the halls of power at the World Economic Forum, addressing the titans of global business and politics, huddling with a few of them for closed-door sessions and being publicly belittled by officials from the United States government.
On Friday, as the five-day conclave came to a close, she returned to her original domain: a protest outdoors. Shoulder to shoulder with her youth activist peers, Ms. Thunberg marched along the narrow road that winds through this village in the Swiss Alps, holding her signature handmade black-and-white sign that read, in her native Swedish, “school strike for the climate.”
Speaking to reporters just before the march set off, Ms. Thunberg and four youth activists from Europe and Africa rebuked business and government leaders at the World Economic Forum for not taking climate action and warned that they would continue to press them to stop investing in fossil fuels. Those demands, Ms. Thunberg noted, “have been completely ignored.”
Asked about a suggestion by Treasury Secretary Steven Mnuchin that she learn economics in college before calling for divestment, Ms. Thunberg brushed off such criticisms as irrelevant. “If we care about that, we wouldn’t be able to do what we do,” she said.
In her addresses at Davos, Ms. Thunberg has repeatedly cited scientific consensus that the world as a whole is burning through what scientists call the carbon budget, which is the cumulative amount of carbon dioxide that can amass in the atmosphere over a period of time to keep temperatures within certain thresholds. Earlier this week, as the annual conference opened, concentrations of carbon dioxide in the atmosphere hit a record.
This year, the business titans who attended the conference seemed to have awakened to the threats that accelerating global warming poses to society — and their own company bottom lines. Many investors and executives who for decades had brushed off scientific warnings about climate change this week rallied around the need to address its risks, though few provided details on exactly how, and how quickly, they would transition away from an economy based on fossil fuels.
Vanessa Nakate, 23, a climate campaigner from Uganda who joined the news conference with Ms. Thunberg, said it wasn’t enough that the business elite was paying attention to activists like her. “They’re listening to us. If they don’t act it’s because they’re ignoring it.”
“We got the feeling W.E.F. was locked in a bubble of positivity,” said Loukina Tille, 18, from Switzerland, referring to the forum by its initials.
Luisa Neubauer, 23, from Germany, said that while the “discourse” at Davos demonstrated a new enthusiasm among company bosses to rein in the emissions of planet-warming gases, that would not deter the youth climate movement from pressing specific companies to get out of fossil fuels.
“We will hold each of those speakers accountable,” she said. “It is their money that is fueling this crisis.”
One measure of their effect on this high-level gathering was the kind of attention they received from the officials in attendance. President Trump earlier in the week obliquely referred to them as “the heirs of yesterday’s foolish fortune tellers.” Chancellor Angela Merkel of Germany urged world leaders on Thursday to “take the impatience of young people positively and constructively.”
Andrew Steer, president of the World Resources Institute, said the youth movement had acted as “a very valuable nudge” to business and political leaders to transition away from a global economy driven by fossil fuels.
No one can come to Davos anymore and not understand climate science, he said. “You look stupid, frankly,” he said. “You can no longer ignore it. That’s the breakthrough.”
Ms. Thunberg, a soft-spoken young woman who discusses openly her struggles with a neurobiological condition called Asperger’s syndrome, has emerged as an unlikely moral authority figure on the need to avert the worst effects of climate change. And she has also sought to shift the attention away from her as an individual.
That was on full display Friday as she pressed reporters to seek answers from the other speakers on the stage with her and tried to stay in the background during the march and rally outside.
The march began just before midday, with blazing snow white mountains as the backdrop. Dozens of mostly young people walked up the road that winds through the ski resort town. Most of the storefronts had turned into pop-up company pavilions, including the various banks and technology companies that invest in and work with fossil fuel companies.
“What happens in the Arctic doesn’t stay in the Arctic,” read a sign that Alexandria Villasenor, a teen climate activist from Davis, Calif., held up.
“Planet over Profit,” read another sign.
They marched slowly to the end of the road and stopped at a small park.
“Power to the people,” they chanted.
And then, “The oceans are rising, and are we.”
Behind them stood a storefront that BlackRock, the world’s largest institutional investor, had taken over for the week. Its chief executive, Larry Fink, said last week that it would place climate change at the center of its investment strategy. This week, he walked around the conference wearing a wool scarf featuring a striped design that represents decades of warming temperatures globally.
Marc Santora contributed reporting from London.