Greta Thunberg Is Taking a Holiday Break. ‘You Need to Take Rest.’

LONDON — Greta Thunberg says she needs a break.

The seemingly tireless 16-year-old climate activist — who has sailed across the Atlantic twice as she has become the most prominent face in the movement to fight global warming, and lectured the world’s leaders that they were not doing enough to address the problem — recently told reporters in Spain:

“I will be home for Christmas and then I will take a holiday break because you need to take rest. Otherwise you cannot do this all the time.”

The activist, who last week was named by Time magazine as its person of the year, has faced attacks from the far right, as well as from the president of the United States and other adults who find her intense and her message that the world is facing a crisis unsettling. Now others have weighed in, including a German railway company.

President Trump, who was Time magazine’s person of the year in 2016, called this year’s choice “ridiculous” on Twitter. He urged Ms. Thunberg to “work on her anger management problem” and to “chill.”

The Trump campaign also distributed a Photoshopped image of the Time cover with the president’s head superimposed on the teenager’s body.

Earlier in the week, Jair Bolsonaro, Brazil’s far-right president, referred to her as a “brat,” Reuters reported.

Ms. Thunberg also came under criticism last week when she joined thousands of students in the north Italian city of Turin on Friday to pressure the government to take action on carbon emissions. She had just been in Madrid for a United Nations climate conference.

While addressing the climate protest, Ms. Thunberg called on crowds to “put leaders against the wall,” according to the BBC.

Critics scolded that she was advocating violence, leading her to apologize and explain that the true meaning of her words had been lost in translation.

On Saturday, she said that she was “against any form of violence,” and that her remark had been nothing more than an unfortunate translation of an expression meaning “to hold someone accountable” in her native Swedish.

Then on Sunday, she posted a photo on Twitter that showed her sitting next to her packed suitcases on the floor of a German train that she described as “overcrowded.”

The German railway company appeared to take umbrage, first thanking her on Twitter “for supporting us railroad workers in the fight against climate change!” but adding, “It would have been even nicer if you had also reported how friendly and competent you were looked after by our team at your seat in first class.”

In a follow-up tweet, she explained that the train she had taken from Basel, a city in northwestern Switzerland, had been “taken out of traffic.”

“So we sat on the floor on 2 different trains,” she said, adding that she got a seat after Göttingen, a German town. “Overcrowded trains is a great sign because it means the demand for train travel is high!” she wrote.

Refusing to fly because of the outsize greenhouse gas emissions from aviation, she traveled across the Atlantic on an emissions-free yacht to make a fiery speech at the United Nations Climate Action Summit in New York in September this year.

Then in November she set sail from Hampton, Va., to Spain for the 25th United Nations Climate Change conference.

This month, the Oscar-nominated director Darren Aronofsky called her “the icon the planet desperately needs” in an Op-Ed article for The New York Times.

After Mr. Trump’s mocking tweet this week, Ms. Thunberg changed her Twitter bio to identify herself as: “A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend.”

Prominent figures also came to her defense.

“What kind of president bullies a teenager?” Joseph R. Biden Jr., the former vice president and a Democratic presidential hopeful, wrote on Twitter on Thursday. He added that the president “could learn a few things from Greta on what it means to be a leader.”

Michelle Obama, the former first lady, also weighed in, telling Ms. Thunberg to not let “anyone dim her light.”

“Ignore the doubters and know that millions of people are cheering you on,” she wrote.