Teenage climate activist Greta Thunberg has brushed off a critic who told her to go and study economics.
US finance chief Steve Mnuchin dismissed the Swede's call for governments and companies to cut back on fossil fuel use.
"Is she the chief economist? Who is she? I'm confused," he said. Then following a brief pause, he said it was "a joke".
"After she goes and studies economics in college, she can come back and explain that to us,'' he concluded.
Thunberg, 17, speaking at the World Economic Forum (WEF) in Davos on Friday, dismissed Mnuchin's barb saying it had no effect on her.
"We are constantly criticised in this way," she said. "If we were careful we could not do what we do. We put ourselves in the spotlight."
Watch Greta Thunberg's press conference at Davos
``"The situation is not being treated like the crisis it is," Thunberg added.
"Before we came here, we had a few demands. Obviously, those demands have been completely ignored."
Thunberg, who was selected as Time's Person of the Year for 2019, has returned to Davos, Switzerland, this week to press her call for businesses, world leaders and others to take action in the face of scientific evidence showing that temperatures on Earth are rising.
She spoke to reporters along with four other young climate activists, before they set off through the streets of Davos for the latest weekly ``Fridays for Future'' campaign that she launched.
At the news conference, Thunberg sought to share the spotlight, deferring to her fellow activists: Vanessa Nakate of Uganda, Loukina Tille of Switzerland, Luisa Neubauer of Germany, and Isabelle Axelsson of Sweden.
They said they'd noticed a "discourse change" at the WEF.
"This is, of course, good, but we've never striked for discourse change," said Neubauer. "From the first day onward, we've striked for actual climate action."
Asked about the statements targeting her from an American minister on Thursday, Greta Thunberg said they had "no effect" on her.
"This obviously has no effect. We are constantly criticized in this way. If we were careful we could not do what we do. We put ourselves in the spotlight," said the activist.
The young activists also criticised the media, saying they were focusing too much on climate activists instead of the climate crisis.
"At the moment there is an insane focus on climate activists, on people. [...] The media really need to actually start speaking about what is needed to be done, not only sensational headlines," said Axelsson.
After the press conference, the activists were set to join the Friday for Future protest in Davos.