Teenage climate activist Greta Thunberg has brushed off criticism and mockery from the US Treasury chief, saying Friday his comments have "of course no effect" on her and fellow campaigners.
The 17-year-old Swedish star's comments marked a final coda to the four-day World Economic Forum summit in Davos, where a major theme was tension between environmental activists who want to protect the Earth and Trump administration officials and business titans who want to exploit its resources for jobs, profits and economic growth.
Many of the 3,000-odd business leaders, government officials, UN representatives, civil society advocates and other elites on hand have found themselves somewhere along the spectrum between the positions staked out by Trump and Thunberg.
She sat in on Trump's speech Tuesday to the forum, but that did little to bridge their ideological differences.
On Friday, Thunberg, who has been battling the flu this week, kept her lucidity and apologised for her "low energy" - a term Trump has often used to mock rivals - as she spoke out again in favour of science and facts, and set off on yet another "Fridays for Future" march through snowy Davos streets.
At a news conference before the march, she acknowledged young climate activists "are being criticised all the time" in comments like those from US Treasury chief Steven Mnuchin.
Mnuchin had a day earlier dismissed Thunberg's suggestion that governments and companies cut back dramatically on fossil fuels with a condescending barb.
"Is she the chief economist? Who is she? I'm confused," he said.
Then, following a brief pause, he said it was "a joke."
"But not in an aggressive way."