Fox News apologized to 16-year-old climate activist Greta Thunberg on Monday after a conservative pundit called her a "mentally ill Swedish child."

Thunberg, who has Asperger's syndrome, delivered a powerful speech at the United Nations earlier in the day about the impact of climate change on her generation. The speech was then the subject of a segment on Fox News' The Story, featuring reaction from conservative writer and the Daily Wire host Michael Knowles and progressive podcast host Chris Hahn. "The climate hysteria movement is not about science," Knowles said. "If it were about science, it would be led by scientists, rather than by politicians and a mentally ill Swedish child who is being exploited by her parents and by the international left."

Stephanie Keith / Getty Images Greta Thunberg speaks at the Climate Action Summit at the United Nations on Monday.

Hahn told Knowles he should be ashamed. "Relax, skinny boy. I got this," he said as Knowles began to interrupt. "You're attacking a child. You're a grown man." Knowles continued: "She is mentally ill. She has autism. She has obsessive-compulsive disorder. She has selective mutism. She had depression." Fox News apologized for the comments on Monday night and told BuzzFeed News the network had “no plans" for Knowles to appear as a guest on future shows. In addition to on-air appearances, Knowles writes opinion articles on FoxNews.com. "The comment made by Michael Knowles who was a guest on The Story tonight was disgraceful — we apologize to Greta Thunberg and to our viewers,” a Fox News spokesperson said. Scientists, of course, are saying a lot about a climate change, and Thunberg is using her new fame to ask global leaders to listen to them. The teen also recently opened up about her diagnosis in a series of tweets.

When haters go after your looks and differences, it means they have nowhere left to go. And then you know you’re winning! 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. #aspiepower

"I have Aspergers and that means sometimes I'm a bit different from the norm. And — given the right circumstances — being different is a superpower," she wrote. She added that "many ignorant people" see the syndrome as a negative, and she acknowledged she has been limited in the past, particularly before she began her strike from school to bring attention to climate change. "Before I started school striking I had no energy, no friends and I didn't speak to anyone. I just sat alone at home, with an eating disorder," she said. "All of that is gone now, since I have found a meaning, in a world that sometimes seems shallow and meaningless to so many people." Despite the apology from Fox News, Knowles stood by his comments, pointing to the book Thunberg's mother wrote that included the family's experiences with Greta's diagnosis. On Twitter, Knowles shared the Fox News clip and added, "There is nothing shameful about living with mental disorders." But a commenter criticized the idea that people with Asperger's could not be taken seriously for their opinions.

Of course not. But children should never be exploited for political purposes, and mentally ill children are particularly vulnerable. https://t.co/S5ujB0XqTp

"Of course not," Knowles wrote. "But children should never be exploited for political purposes, and mentally ill children are particularly vulnerable." Later in the evening Monday, a Fox News host mocked Thunberg's activism. Laura Ingraham played a clip of Thunberg's speech to the UN on her program, comparing it to the horror film Children of the Corn.

Laura Ingraham compares Greta Thunberg to Children of the Corn