Svante Thunberg says he was concerned about his daughter’s school strike but that her campaigning had helped her beat depression

Greta Thunberg’s father has opened up about how activism helped his daughter out of depression but still worries about how she will deal with the impact of her international fame.

Speaking to the BBC to mark his daughter’s guest-editing slot on the Today programme, Svante Thunberg revealed he thought it was a “bad idea” for Greta to stage the school strike that catapulted her into the public eye.

The programme also featured a discussion between Greta Thunberg and the veteran naturalist Sir David Attenborough, in which the latter praises the teenager for raising awareness of the climate crisis.

She had “achieved things that many of us who have been working on it for 20-odd years have failed to achieve – that is you have aroused the world”, said Sir David, adding that she was the main reason climate was discussed during the British election campaign.

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Svante Thunberg reveals how activism had changed the outlook of the teenager, who suffered from depression for “three or four years” before she began her school strike protest outside the Swedish parliament. She was now “very happy”, he said.

“She stopped talking ... she stopped going to school,” he said of her illness, adding that it was the the “ultimate nightmare for a parent” when Greta began refusing to eat.

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Svante Thunberg, an actor, said he and his wife, the opera singer Malena Ernman, scaled back their professional lives to spend more time with Greta in order to help her overcome her depression. He became vegan and his wife stopped travelling to concerts by plane.

He said Greta became energised about green issues as the family began talking more about environmental issues. He accompanied her on her tour of the United States and visit to the Madrid climate crisis this year

“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,” Svante Thunberg said. “I have two daughters and to be honest they are all that matters to me. I just want them to be happy.

Facebook Twitter Pinterest Greta Thunberg with BBC Today programme presenter Mishal Husain. Photograph: BBC/PA

“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 was concerned about the negative comments his daughter attracted in the media and online and “all the hate that that generates”. But his daughter dealt with it “incredibly well”.

“Quite frankly, I don’t know how she does it, but she laughs most of the time. She finds it hilarious.”