Even President Trump managed to avoid laying into the 17-year-old climate activist Greta Thunberg at the World Economic Forum in Switzerland this week. But Treasury Secretary Steven Mnuchin couldn’t resist a swipe, telling reporters in Davos that he won’t take advice from Thunberg until she goes and gets a college degree in economics. Mnuchin was asked whether the U.S. needed to follow Thunberg’s suggestion and immediately divest from fossil fuels. “Is she the chief economist or who is she? I’m confused,” Mnuchin said, before adding it was “a joke. That was funny.” He then went on: “After she goes and studies economics in college, she can come back and explain that to us.” Earlier this week, Thunberg joined 20 other young climate activists at the event and called on all of those attending the forum to stop the “madness” of fossil-fuel extraction.