Teen climate change activist Greta Thunberg often brings out the worst in her adult critics. When she visited the U.S. in September of last year, Fox News's Laura Ingraham compared her to the murderous pre-teens in Children of the Corn. Former Trump adviser Sebastian Gorka called her brainwashed and said her parents should be brought up on child abuse charges. Right-wing Daily Wire podcaster Michael Knowles said she was "mentally ill." And Donald Trump himself has frequently mocked her on Twitter, most recently tweeting, in typical Trumpian projection, that she "must work on her Anger Management problem."

Given his boss's approach, it's not surprising that 57-year-old treasury secretary Steve Mnuchin would resort to ad hominem attacks on the young activist. This week, Mnuchin and Thunberg are both at the World Economic Forum in Davos, Switzerland, and a reporter asked the secretary about how combatting climate change would affect the U.S. economy. The exchange, according to the Washington Post, went:

Reporter: "Greta Thunberg has called for public and private sector divestment from fossil fuel companies. Does that pose a threat to this U.S. economic growth that you guys are talking about?"

Mnuchin: "Is she the chief economist or who is she? I’m confused."

Reporter: "Greta Thunberg."

Mnuchin: "It’s a joke!" [some laughter follows.] "After she goes and studies economics in college she can go back and explain that to us."

Thunberg responded soon after on Twitter:

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. 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.

The Post followed up with an actual economist, the extremely credentialed Gernot Wagner who has a master’s degree in economics from Stanford University, a master’s in political economy and government from Harvard, and a PhD in political economy and government also from Harvard. Wagner sides with Thunberg, saying that economics is exactly where one front of the fight against climate change needs to play out. "It’s Economics 101 that tells us that when there is a difference between private costs and costs to society, that difference ought to be included in one’s decision-making. And when I say ought, of course the private individual won’t; it’s up to somebody in a position of power—let’s say the secretary of Treasury—to want to guide economic policy in the right direction."

For his own education, Mnuchin attended Yale University, where, presumably, he learned the basic economics that helped him earn the nickname "Foreclosure King." According to David Dayen, a reporter for The Intercept, a 2013 memo from top prosecutors to California's attorney general accused OneWest Bank, where Mnuchin was CEO and chairman as well as a partial owner, of repeatedly breaking foreclosure laws, claiming that the bank "rushed delinquent homeowners out of their homes by violating notice and waiting period statutes, illegally backdated key documents, and effectively gamed foreclosure auctions." An audit found that OneWest also violated the Service Members Civil Relief Act by initiating foreclosures on the homes of the families of 54 active duty service members. The bank also attempted to foreclose on the home of a 90-year-old woman for being 27 cents behind on a payment.

Mnuchin, who's worth an estimated $400 million according to Forbes, has also repeatedly insisted that tax cuts pay for themselves, a claim which has yet to bear out. Despite this, Mnuchin also announced at Davos that the Trump administration working on a second round of massive tax cuts.