Teenage activist Greta Thunberg gave an impassioned speech at the United Nations Monday urging world leaders to do more to combat climate change and repeatedly asked, "How dare you?"
President Donald Trump responded to coverage of her address with a mocking tweet.
Thunberg had said: "We are in the beginning of a mass extinction and yet all you can talk about is money. You are failing us."
She excoriated world leaders for having "stolen my dreams and my childhood with your empty words."
Trump shared a video of the Swedish 16-year-old's address and wrote: "She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!"
Trump had spent only a few minutes at the climate summit, a centerpiece of this year's U.N. General Assembly schedule.
Thunberg arrived to U.S. last month on a yacht equipped with solar panels and underwater turbines after having set sail by England on a two-week voyage to attend the summit. She participated Friday in a global youth climate strike, the latest show of force from a movement she started with lone protests in front of her country's parliament about a year and a half ago.
Clips of her speech went viral on social media, along with a GIF that showed her appearing to glare at Trump when he dropped in on the summit.
Trump wasn't the only critic who ridiculed her efforts on Monday.
The Daily Wire’s Michael Knowles on Fox News accused Thunberg of being "mentally ill" and "exploited by her parents and the international left." Fox News later apologized for what the network called Knowles' "disgraceful" comments, NBC News reported.
Thunberg, who has Asperger's syndrome, has responded to previous criticism of her appearance and mannerisms.
"I have Aspergers and that means I’m sometimes a bit different from the norm. And - given the right circumstances- being different is a superpower," she wrote on Twitter last month.
On Tuesday morning, her Twitter account had a new bio. It read: "A very happy young girl looking forward to a bright and wonderful future."