When Greta Thunberg testified before Congress last fall, the teenaged climate activist pointedly offered no words of her own. Just a copy of the latest report of the Intergovernmental Panel on Climate Change.

“I don’t want you to listen to me,” she said. “I want you to listen to the scientists.”

President Donald Trump, on the other hand, who has been forced repeatedly in recent weeks to address climate change despite his administration’s resolve to ignore it, has had plenty to say. But the more he’s talked, the less clear it’s been to many people whether he knows enough about the science to deny it. 

“It’s a very serious subject,” he said in response to one reporter’s climate question, adding that he had a book about it that he’s going to read. The book: Donald J. Trump: Environmental Hero, written by one of Trump’s business consultants. 

Trump seemed no more schooled in the fundamentals by the time he faced-off this week with Thunberg at the World Economic Forum in Davos, which this year was more focused on climate than the annual conclave has ever been in the past.  

While Thunberg delved into fine points like the pitfalls of “carbon neutrality” and the need for technologies that can scale, Trump did not get into specifics. 

“We must reject the perennial prophets of doom and their predictions of the apocalypse,” Trump said. “They are the heirs of yesterday’s foolish fortune-tellers—and I have them and you have them, and we all have them, and they want to see us do badly, but we don’t let that happen.” 

The dueling statements by the resolute young activist and the president of the United States were quickly cast by the media as a David and Goliath dust-up—a kind of reality show version of the wider debate over climate change. And while in political stature, Thunberg might have been David, like the Biblical hero she clearly outmatched Goliath, if the measure was knowledge about climate change.

Chief executives of the world’s largest oil companies who attended Davos did not join in Trump’s dismissal of climate concerns.They reportedly were busy huddling in a closed-door meeting at the Swiss resort, discussing how to respond to the increasing pressure they are feeling from climate activists and their own investors.

It’s been clear for some time that Trump also is feeling that pressure. Last year, after Republican polling showed his relentless rollback of environmental protection was a political vulnerability, especially with young GOP voters, the White House sought to stage events to showcase its environmental accomplishments. And Trump has repeatedly boasted that, “We had record numbers come out very recently” on clean air and clean water, despite recent research finding  that deadly air pollution in the U.S. is rising for the first time since 2009. 

At Davos, Trump announced that the U.S. would join the One Trillion Trees initiative, infusing his announcement with an appeal to his evangelical base. “We’re committed to conserving the majesty of God’s creation and the natural beauty of our world,” he said.

But the announcement was untethered to the real-world dwindling of the world’s most important forests, and to facts like the logging his own administration has opened up in the Tongass, or the accelerating destruction in Brazil. 

Again, it was Thunberg who, without mentioning Trump by name, provided perspective.

“We are not telling you to ‘offset your emissions’ by just paying someone else to plant trees in places like Africa while at the same time forests like the Amazon are being slaughtered at an infinitely higher rate,” she said. “Planting trees is good, of course, but it’s nowhere near enough of what is needed and it cannot replace real mitigation and rewilding nature.”

Asked to respond to Thunberg, Trump parried with a question. “How old is she?” he asked.