At the same conference this week, Thunberg and Trump gave what The Washington Post described as "a head-on collision of worldviews"

Though President Donald Trump has mocked teenage climate activist Greta Thunberg before, he did not mention her by name in a speech Tuesday that nonetheless implied she was a “prophet of doom” — with her reportedly in the audience.

Both Trump, 73, and 17-year-old Thunberg, made speeches Tuesday at the World Economic Forum in Davos, Switzerland. Each year, a (sometimes controversial) group of business and political leaders gathers there to discuss the world’s major issues.

Climate change was among those issues this year, where Thunberg and Trump gave what The Washington Post described as “a head-on collision of worldviews.”

Thunberg was in attendance for Trump’s speech, according to the BBC.

In his Tuesday speech, according to the Post, the president touted the economy: “America is thriving; America is flourishing, and, yes, America is winning again like never before.” But he dismissed fears about the perils of man-made climate change. (And he did not mention his ongoing impeachment trial in the Senate.)

Trump referred to activists such as Thunberg, without naming her specifically, as “these alarmists [who] always demand the same thing — absolute power to dominate, transform and control every aspect of our lives.”

He called them “heirs of yesterday’s foolish fortune tellers,” the BBC reported.

Trump and Greta Thunberg
From left: President Donald Trump and Greta Thunberg
| Credit: Markus Schreiber/AP/Shutterstock; GIAN EHRENZELLER/EPA-EFE/Shutterstock

The international scientific community has for years agreed that humans are responsible for worsening climate change and that the continued heating of the earth will have devastating — perhaps existential — consequences.

Numerous countries, including the U.S., have worked to change some of the underlying environmental dynamics, including curbing carbon emissions. But President Trump, long a climate change skeptic, said after he took office that the U.S. would leave the Paris climate agreement, one such international effort, insisting it was a “bad deal.”

“We will never let radical socialists destroy our economy, wreck our country or eradicate our liberty,” he said in Davos on Tuesday, according to the Post.

Speaking not long after Trump, Thunberg was equally direct.

“Our house is still on fire,” she said, according to The New York Times. “Your inaction is fueling the flames by the hour.”

Urgent, even cutting, Thunberg told her audience, “I wonder, what will you tell your children was the reason to fail and leave them facing the climate chaos you knowingly brought upon them?”

“Let’s be clear. We don’t need a ‘low carbon economy.’ We don’t need to ‘lower emissions,’ ” she said. “Our emissions have to stop.”

Trump is no stranger to criticizing Thunberg. And Thunberg is very familiar with clapping back at him, in her way.

In December, the president tweeted angrily about Thunberg being named TIME’s “Person of the Year.”

“So ridiculous,” he wrote. “Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!”

Before too long, Thunberg had a new Twitter bio: “A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend.”

Thunberg responded similarly after Trump’s dig at her in September, when he tweeted, sarcastically, “She seems like a very happy young girl looking forward to a bright and wonderful future.”

Thousands Of Americans Across The Country Participate In Global Climate Strike
Greta Thunberg
| Credit: Drew Angerer/Getty
Time person of the year: Greta Thunberg
Greta Thunberg

A teen who has become one of the global faces of the importance and — in her words — woeful inadequacy of the world’s response to climate change, Thunberg made international headlines throughout 2019, capped by her TIME honor.

In 2018, she began “striking” from school to raise awareness about climate change. That has inspired numerous other such protests.

Thunberg has not been shy about her feelings on Trump’s politics. She went viral for an icy stare she seemed to level his way when he crossed paths with her at the United Nations in September.

“I don’t see what I could tell him that he hasn’t already heard,” she said on Ellen DeGeneres’ show in November, “and I just think it would be a waste of time, really.”

On Tuesday in Davos, however, she said, “This is not about right or left. We couldn’t care less about your party politics,” she said. “From a sustainability perspective, the right, the left as well as the center have all failed. No political ideology or economic structure has been able to tackle the climate and environmental emergency.”