The father of Swedish teenage climate change activist Greta Thunberg has told the BBC he will be happy when she returns to school after her year out campaigning, but despite the attention she received, her activism has made her a happier child and she is "in a good place".

Svante Thunberg was speaking on the BBC Radio 4 news program Today. Every Christmas, a number of high-profile public figures are invited to be guest editors, with one of this year's being the 16-year-old.

He revealed that before she discovered activism, Greta had suffered from depression, stopped going to school and even, in what he called the "ultimate nightmare for a parent", stopped eating.

But being diagnosed with Asperger's syndrome, a form of autism, had given her a new clarity of vision which found its focus in the issue of climate change.

Her lone school strike protest in 2018 has become a global movement, which has seen her nominated for the Nobel Peace Prize, address the United Nations and come in for personal criticism from US President Donald Trump, which she batted off lightheartedly.

"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," said Greta's father.

"She dances around, she laughs a lot, we have a lot of fun－and she's in a very good place."

The levels of abuse she has received because of her public profile are a worry, he admitted. Previously, Greta has spoken of how she is picked on because of "my looks, my clothes, my behavior and my differences", and he said the hate generated by fake news allegations was particularly alarming but she handles it "incredibly well ... quite frankly, I don't know how she does it, but she laughs most of the time. She finds it hilarious".

Thunberg has accompanied his daughter on her global travels this year and said he thought she "really wants to get back to school" and that he looked forward to a "less intense" future.

In another part of the program, Greta interviewed veteran British wildlife broadcaster David Attenborough, who she has hailed as her inspiration, over Skype.

The 93-year-old described her impact as "astonishing". He said: "She has achieved things that many of us who have been working on for 20-odd years have failed to achieve－and that is you have aroused the world."

Earlier this year, in an exclusive interview with China Daily, Attenborough paid tribute to the difference Greta Thunberg had made to public debate.

"At the age of 16, you can't pretend you have the knowledge and science of a lifetime but you can see things very clearly, and young people do see things very clearly. It's their future so they have a better right to a powerful opinion," he said.