President Donald Trump mocked teenage Swedish climate activist Greta Thunberg on Monday evening, after she sent leftists swooning with her tearful, accusatory speech at the United Nations earlier in the day in New York.

Thunberg, who came to the U.S. on a “zero-emissions” sailboat owned by the royal family of Monaco, said, in part (via NPR):

My message is that we’ll be watching you. This is all wrong. I shouldn’t be up here. I should be back in school on the other side of the ocean. Yet you all come to us young people for hope. How dare you! You have stolen my dreams and my childhood with your empty words. And yet I’m one of the lucky ones. People are suffering. People are dying. Entire ecosystems are collapsing. We are in the beginning of a mass extinction, and all you can talk about is money and fairy tales of eternal economic growth. How dare you! … You are failing us. But the young people are starting to understand your betrayal. The eyes of all future generations are upon you. And if you choose to fail us, I say: We will never forgive you.

At one point, Thunberg and Trump crossed paths, when the president made an unexpected visit to the UN’s climate meeting.

Greta Thunberg’s glare at Donald Trump is giving me the energy to get through this Monday pic.twitter.com/xdM0rdI2ln — Sam Stryker (@sbstryker) September 23, 2019

The left hailed Thunberg as a hero, using her speech to attack the president, who famously pulled the U.S. out of the Paris Climate Accords in 2017. Several of Trump’s would-be rivals in the 2020 election praised her speech.

In response, Trump offered one of his signature tweets:

She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see! https://t.co/1tQG6QcVKO — Donald J. Trump (@realDonaldTrump) September 24, 2019

As bestselling author — and Breitbart News entertainment editor — Jerome Hudson notes in his book, 50 Things They Don’t Want You to Know, the U.S. has lowered emissions while growing its economy through the use of fracking — a practice that most of the Democratic candidates want to stop.

Thunberg did not endorse nuclear power — a zero-emissions technology — or any other solutions.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He earned an A.B. in Social Studies and Environmental Science and Public Policy from Harvard College, and a J.D. from Harvard Law School. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.