A leading psychologist has voiced his concern about the mental well-being of autistic teenage climate change activist Greta Thunberg.

Greta made international headlines last week after inspiring millions of people across 150 countries to take to the streets for the Global Strike 4 Climate on Friday.

The 16-year-old schoolgirl from Sweden then made a passionate speech berating world leaders for climate inaction at the UN summit in New York on Tuesday.

But as the teenager continues to divide opinion for her opinions on climate change, one of Australia's most-high profile psychologists has accused the girl of being an 'entitled political pawn' in need of treatment.

Dr Michael Carr-Gregg compared Greta's position in the spotlight to the fame of a child TV star who could 'burn out' after being thrust into the spotlight.

The 16-year-old Swedish environmental activist went head-to-head with President Donald Trump on social media after berating global leaders at the UN summit in New York on Tuesday

'I worry about her going the same as child TV stars, that they just burn out and potentially have a disastrous psychological outcome,' he told 3AW on Wednesday.

'Can I make it clear, I am not a climate change denier. I actually think that we do need to do more about saving the planet.'

Dr Carr-Gregg said he was wary of Greta's Asperger's and history of mental health in his analysis of the teenager, who he believes has a 'sense of entitlement'.

'I am worried that we use a kid like this, who arguably should be getting treatment because she's said she's had anorexia, said she's got Asperger's and said she's battled depression,' he said.

'As a parent, if this was my child, I'm not sure I'd be putting them on the world stage.'

Dr Carr-Gregg said he was worried about Greta's future, her current psychological health and how it would impact other young people.

'It sends a message to other teenagers that they can speak to adults in this very, very dismissive way',' he said.

'She seems to be caught up in a doomsday scenario where she's massively exaggerating the threats posed by climate change and that has a flow-on effect because it causes all this existential anxiety in our children, hence the climate strikes,' he said.

He said kids should be in school but are instead rallying because 'they've been convinced the end of the world is nigh'.

'She's now put herself at the centre of worldwide either Greta-phobia or Greta-mania and I don't think any 16-year-old girl should be,' he said.

Dr Carr-Gregg mentioned the 'Twitter war' between Greta and Donald Trump where the president appeared to mock the teenager.

'She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!,' Mr Trump tweeted following Greta's impassioned speech.

The climate activist swiftly responded by changing her Twitter bio to 'A very happy young girl looking forward to a bright and wonderful future.'

Dr Michael Carr-Gregg compared Greta's position in the spotlight to the fame of a child star who could 'burn out' after being thrust into the spotlight

The Swedish 16-year-old scolded international delegates telling them 'you have stolen my my dreams and my childhood with your empty words' during a speech at the UN headquarters in New York

In her explosive speech, Greta said: 'We are in a mass extinction. And all you can talk about is money and fairytales of eternal economic growth. How dare you!'

The teenager first rose to fame a year ago when she held a one-person climate strike out the front of Swedish parliament.

The School Strike for Climate protests quickly rose to success, with millions of people across the world rallying for action during the most recent demonstrations on Friday.

Dr Carr-Gregg said he didn't think children should be used as 'political props'.

Donald Trump appeared to mock Greta on his Twitter account, so the teenager changed her bio to his insult 'she seems like a very happy young girl looking forward to a bright and wonderful future'

'My criticism isn't so much of her, but her parents and the climate change activists who use her shamelessly and I think that the Left can be somewhat hypocritical at times,' he said.

Dr Carr-Gregg said the rest of world needs to put pressure on China and India - the largest emitters.

'I think she's setting herself up for massive disappointment,' he said. 'It's the rest of the world who needs to be pressuring those countries, not one single 16-year-old girl.'

The psychologist said that because Greta is a 16-year-old female 'no one is allowed to debate' her views.

'We all just have to lie down and accept it,' he said.

Prime Minister Scott Morrison has also come out swinging against Greta's tough stance on global warming, saying 'we've got to let kids be kids'

Prime Minister Scott Morrison has also come out swinging against Greta's stance on global warming, saying 'we've got to let kids be kids.'

He said children need to be protected from 'needless anxiety' and reminded the younger generation that they live in a 'wonderful country and pristine environment.'

'I don't want our children to have anxieties about these issues,' he said.

'They will also have an economy to live in as well.'