Treasury Secretary Steve Mnuchin on Thursday became the latest member of the Trump administration to mock Greta Thunberg, the 17-year-old activist who has spent her adolescence calling adults to account for their failure to act on climate change.

Asked by a reporter at the World Economic Forum in Davos whether the climate policies Thunberg advocates would hinder US economic growth, Mnuchin answered, “Is she the chief economist, or who is she? I’m confused.”

“It’s a joke,” he went on. “After she goes and studies economics in college she can come back and explain that to us.”

It was one in a long line of belittling comments that politicians and pundits on the right have made about Thunberg in recent months. President Trump has led the charge, sarcastically tweeting in September that Thunberg seemed like “a very happy young girl looking forward to a bright and wonderful future.” In December, after Thunberg was named Time magazine’s Person of the Year for 2019, Trump called the choice “ridiculous” and said the activist should “go to a good old fashioned movie with a friend.”

Others, meanwhile, have questioned Thunberg’s mental health. Conservative commentator Michael Knowles, for example, called Thunberg a “mentally ill Swedish child” on Fox News in September. The comment appeared to refer to the fact that Thunberg has been open about having Asperger’s syndrome, an autism spectrum disorder that is not a mental illness.

Despite her young age, Thunberg is now a major public figure, addressing the United Nations climate conference and appearing frequently on television. So some criticism of her is certainly to be expected. But the attacks on Thunberg by Mnuchin, Trump, and others seem to focus on her identity more than her ideas — the message is that because she is a teenage girl who has Asperger’s, she shouldn’t be speaking on a world stage.

Thunberg and other young activists, however, have argued that the world needs to hear their voices because they are the ones who will be most affected as climate change grows more severe in the coming years. And Thunberg has suggested that perhaps her critics resort to personal attacks because they can no longer deny the science of climate change: “when haters go after your looks and differences,” she tweeted last year, “it means they have nowhere left to go.”

Trump and others have repeatedly mocked Thunberg

Thunberg, who is Swedish, went on a one-woman strike against climate change in August 2018, and gained greater worldwide fame in 2019 when she traveled by boat to New York City to attend the UN climate summit. In her speech before the summit in September, which quickly went viral, she delivered a message to the leaders of the world: “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!”

Trump responded with sarcasm, tweeting, “She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!”

Fox News host Laura Ingraham, meanwhile, juxtaposed Thunberg’s speech with a clip from the 1984 horror film Children of the Corn, joking, “I can’t wait for Stephen King’s sequel, Children of the Climate.”

And Knowles, a conservative podcaster, said in an appearance on Fox News that if the movement for climate action “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.” When challenged, he doubled down, saying Thunberg has “many mental illnesses.”

The mockery continued in December when Thunberg was named Person of the Year.

So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill! https://t.co/M8ZtS8okzE — Donald J. Trump (@realDonaldTrump) December 12, 2019

Once again, Trump appeared to be taking a swipe at her age and gender by saying she should just go to the movies with a friend. He added that she needed help with “Anger Management,” implying that she was having mental or emotional problems rather than a rational response to a climate crisis that threatens her future and those of other young people the world over.

Some people attacking Thunberg on the basis of her mental health seem to be focusing on the fact that she has Asperger’s syndrome. It’s something she’s been open about, tweeting in August that “I have Asperger’s and that means I’m sometimes a bit different from the norm. And — given the right circumstances — being different is a superpower.”

The pattern continued on Thursday, with Mnuchin asking if Thunberg was the “chief economist” and saying she has to go to college before she can talk about climate change. The implication is that Thunberg is too young to have a valid opinion on the climate crisis, even though much of the impact of her activism comes from the fact that her generation will be the ones forced to fight rising sea levels, extreme weather, and wildfires if older generations don’t act.

The attacks aren’t on her speeches — they’re on the person who is speaking

It’s no particular surprise that Trump, members of his administration, and conservatives in the media would disagree with Thunberg on the merits of what she’s saying. After all, the Trump administration pulled out of the Paris climate agreement in 2017, and the president has consistently refused action on the climate. Earlier this month, he admitted that climate change is not a hoax, and pledged to read a book about the environment — a book titled Donald J. Trump: An Environmental Hero.

What’s particularly noteworthy about the attacks, however, is how personal they are, focusing not on the content of Thunberg’s many speeches, but on the fact that a teenage girl is speaking at all.

Mnuchin’s comments stand out because Thunberg has not attempted to weigh in on economic policy. She has merely drawn attention to the science of climate change, which is not, at a basic level, difficult to understand. Thunberg said as much in a response to the treasury secretary, noting that “it doesn’t take a college degree in economics to realise that our remaining 1,5° carbon budget and ongoing fossil fuel subsidies and investments don’t add up.”

My gap year ends in August, but it doesn’t take a college degree in economics to realise that our remaining 1,5° carbon budget and ongoing fossil fuel subsidies and investments don’t add up. 1/3 pic.twitter.com/1virpuOyYG — Greta Thunberg (@GretaThunberg) January 23, 2020

As to why Trump and his allies are so enraged by Thunberg — and so eager to take cheap shots at her rather than debating her ideas — there are a number of possibilities.

Political science and psychology professor Christopher Federico opined on Twitter that perhaps Trump and others “get pissed off when the ‘wrong’ people step out of place and speak too loudly” — that is, they expect a young girl like Thunberg to be quiet and go to the movies.

Jim Sidanius student here. Individuals who are high in social dominance orientation really dig gender and age hierarchy and get pissed off when the 'wrong' people step out of place and speak too loudly. (1/2) https://t.co/kjqBf070vq — Christopher Federico (@ChrisPolPsych) January 23, 2020

It’s certainly possible that Trump feels threatened by the fact that a 17-year-old girl now rivals him by some measures of fame and influence; after all, the president reportedly has a long-standing obsession with being Time’s Person of the Year.

Then there’s Thunberg’s own theory: Her critics are just desperate, with “nowhere left to go” but to attack her personally.

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 pic.twitter.com/A71qVBhWUU — Greta Thunberg (@GretaThunberg) August 31, 2019

Perhaps the evidence of climate change has become so stark that those who oppose action have no choice but to attack the messenger: a teenage girl whose voice, they’ve discovered, is just as loud as theirs.