Greta Thunberg’s father said in a new interview that the 16-year-old climate activist from Sweden has become much happier after taking up the environmental cause — but that he worries about all the “hate” she faces.

Actor-turned-producer Svante Thunberg, 50, told the BBC that he and Greta’s mom, opera singer Malena Ernman, at first objected to their shy daughter becoming an eco-warrior.

“Obviously, we thought it was a bad idea, putting herself out there with all the hate on social media,” he said about Greta, who was diagnosed with Asperger’s syndrome — a form of autism — at age 12.

Her parents realized just how much the existential threat of climate change weighed on her when she became depressed at age 11, stopped talking and eating, and also missed school.

After spearheading a global movement demanding that world leaders take action over climate change, Greta has been nominated for this year’s Nobel Peace Prize and also was named Time magazine’s “Person of the Year.”

Greta’s dad spoke during a special edition of the BBC Radio 4 “Today” program, which was guest-edited by the young climate campaigner. The BBC flew presenter Mishal Husain to Stockholm to interview the teenager and her dad.

Thunberg said he and his wife decided to spend more time with Greta and her younger sister, Beata, at their home, where they began discussing and researching climate change.

Greta accused her folks, as “very active” human rights advocates, of being “huge hypocrites,” Thunberg said.

“Greta said, ‘Whose human rights are you standing up for?’ since we were not taking this climate issue seriously,” he told the BBC.

He said Greta ultimately got “energy” when her parents became more environmentally conscious — such as her mother choosing not to travel by air, and her father becoming vegan and joining her on sailing expeditions to UN climate summits.

“I did all these things, I knew they were the right thing to do … but I didn’t do it to save the climate, I did it to save my child,” Thunberg said. “I have two daughters and to be honest, they are all that matter to me. I just want them to be happy.”

Thunberg said his daughter has “changed” and become “very happy” as a result of her activism.

“You think she’s not ordinary now because she’s special, and she’s very famous, and all these things. But to me she’s now an ordinary child — she can do all the things like other people can,” he said.

“She dances around, she laughs a lot, we have a lot of fun — and she’s in a very good place,” he added.

During the program, Greta also spoke via Skype with environmental filmmaker Sir David Attenborough, who told her she had “woken up the world” to climate change.

The broadcaster and naturalist told Greta that she had “achieved things that many of us who have been working on the issue for 20 years have failed to do.”

Attenborough told Greta that it was depressing when governments in the US, Brazil or Australia indicated they were not taking any notice of what should be done.

“It needs a real electric shock — such as you have produced socially — to bring them to their senses, and let’s hope that shock will go on,” Attenborough told her.

The teen, who has become the global face of anti-greenhouse-gas activism, also has found herself in President Trump’s cross hairs.

In September, Trump tweeted at the teen after she gave an impassioned speech to global leaders at the United Nations, saying they had “stolen my dreams and my childhood.”

“She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!” Trump wrote sarcastically of Thunberg in a tweet.

Thunberg fired back by changing her Twitter bio to: “A very happy young girl looking forward to a bright and wonderful future.”

On Monday, she was asked what she would have said to the president, who has questioned climate science, at the UN summit on global warming.

“Honestly, I don’t think I would have said anything because obviously he’s not listening to scientists and experts, so why would he listen to me?” she said. “So I probably wouldn’t have said anything, I wouldn’t have wasted my time.”