Washington CNN  — 

Treasury Secretary Steven Mnuchin on Thursday dismissed climate activist Greta Thunberg, saying the Swedish teen and Time Person of the Year should first go to college and study economics before she weighs in on US policies and how they relate to the climate crisis.

The remarks came during a press briefing by the secretary during the World Economic Forum in Davos, Switzerland, where the world’s political, business and financial elite turned their attention to the climate crisis and sustainability.

“Greta Thunberg has called for a public and private sector divestment from fossil fuel companies. Does that pose a threat to US economic growth?” a reporter asked Mnuchin.

“Is she the chief economist, or who is she? I’m confused,” the secretary replied. “It’s a joke. After she goes and studies economics in college she can come back and explain that to us.”

Thunberg responded to Mnuchin on Twitter later Thursday.

“My gap year ends in August, but it doesn’t take a college degree in economics to realise that our remaining 1,5° carbon budget and ongoing fossil fuel subsidies and investments don’t add up,” she said. “So either you tell us how to achieve this mitigation or explain to future generations and those already affected by the climate emergency why we should abandon our climate commitments.”

Thunberg has repeatedly criticized top industrial nations for not doing enough to address the crisis. Earlier this week at the conference, Thunberg admonished world leaders for doing “basically nothing” to reduce carbon emissions despite evidence of a looming climate catastrophe.

“Immediately end all fossil fuel subsidies and immediately and completely divest from fossil fuels. We don’t want these things done by 2050, or 2030 or even 2021 – we want this done now,” she said.

Mnuchin’s comments add to mocking remarks President Donald Trump has made toward Thunberg. Last month, he tweeted that Thunberg – who has been open about her diagnosis of Asperger’s, calling it a “superpower” that helps her activism – has “anger management” issues. In September, he called her a “very happy young girl” after she sternly castigated world leaders over the climate crisis.

Trump didn’t address Thunberg by name when he spoke at Davos earlier this week, though he did call for the rejection of “the perennial prophets of doom and their predictions of the apocalypse.”

Asked by a reporter at the conference whether he spoke to other leaders and CEOs about Thunberg and her policies which many of them have supported, Trump said: “No, I didn’t actually. But I would have loved to have seen her speak.” He also said that she should “start working” on other countries that he claimed are contributing more to the climate crisis.

CNN’s Charles Riley, Bianca Britton, Veronica Stracqualursi and Hadas Gold contributed to this report.