Greta Thunberg has met with world leaders, had an audience with the pope and made an impassioned plea to the United Nations. She's done it all in the public eye, facing down trolls and sounding off against politicians, an impressive feat for any teenager.

The 16-year-old has reached millions with her message about the need for urgent action on climate change. She's also inspired people with her public acknowledgement that she's on the autism spectrum.

She calls her autism her "superpower." She has a clear message: she succeeds not in spite of her disability, but because of it.

It's a voice that's refreshing for Anne Borden King and her son Baxter, 9, who are both autistic. They travelled from Toronto to Montreal on Friday to march in the country's largest climate strike.

Empowering for others on the spectrum

The way Thunberg frames her diagnosis as an advantage instead of an obstacle is empowering, says Anne Borden King.

"I think that a lot of the time that we look at how autism is portrayed, it's often portrayed as kind of a burden. As a sadness. And autistic people are often made to be very sort of two-dimensional in media," she says. "And to see someone that big and outright in the media and really a three-dimensional person is incredible."

Watch: Greta Thunberg explains how autism helps her environmental mission

Climate activist Greta Thunberg says the fact she’s on the autism spectrum helps in her blunt criticism of governments' efforts around the world to slow climate change. 4:34

Thunberg tags Instagram posts #aspiepower and writes that "being different is not an illness and the current, best available, science is not opinions — it's facts."

"For those of us who are on the spectrum, almost everything is black or white," she said at a TEDx Talk in Stockholm in November 2018.

To Thunberg, climate change is a black and white issue: It's bad and it needs to be stopped now.

It's that outlook, the singular focus, that makes Greta's message so powerful, says Steve Silberman, a science writer and author of the book NeuroTribes: The Legacy of Autism and the Future of Neurodiversity.

Willingness to speak 'blunt truth'

Thunberg's effectiveness is not about a girl succeeding despite the obstacle of being different, says Silberman.

"I feel like in this case her inability to abide hypocrisy and her willingness to speak the blunt truth and say 'I don't care about being popular' was her using her autism in the best possible way to save the planet."

Anne Borden King and Baxter, 9, travelled from Toronto to Montreal on Friday to march in the country’s largest climate strike. (Evan Mitsui/CBC)

People with autism are often literal thinkers and it's the simplicity and purity of Thunberg's message that is resonating so widely, because it doesn't waver. That appeals to everyone, especially younger people who tend to see the world in less nuanced ways.

But it doesn't mean it is easy. There are aspects of being on the spectrum that might mean extra challenges for the teenage climate activist, Borden King says.

"I mean travelling across the ocean for two weeks on a speeding boat, landing in New York City and just hitting the ground running, it's a lot for anyone," she says. "But then when you add in that there will be sensory issues and then it takes more work, that's an extra amount of energy that she needs to put into it."

People with autism can be extremely sensitive to sensory overload. Noise and being around big groups of people can be especially difficult for people on the spectrum, due to neurological differences in the autistic brain.

Many crave routine and quiet, and are most comfortable when they know what is going to happen next, says Silberman.

Autism is a spectrum, so there are a wide range of ways people with autism see and react to things.

Silberman points out "any statement about all autistic people is apt to be wrong and there are going to be exceptions."

But he says it's a very consistent trait that "autistic people are almost viscerally bothered by hypocrisy and lies."

Critics feed on her difference

Being public about being on the spectrum has also meant additional fuel for those who disagree with her message — everyone from online trolls to high profile politicians, including the president of the United States Donald Trump and People's Party of Canada leader Maxime Bernier.

The bullying is now relying on ableism, says Silberman. When critics talk about Thunberg's "robotic voice or wooden affect," they are trying to invalidate her message using her disability.

It's something Silberman says he thinks she has overcome by speaking the truth in the most simple of terms.

"Greta's consistency, her reliance on the science, her rationality, her stunning maturity. I mean she looks like an adult compared to the people who were attacking her, who look like children, basically," he says.

Borden King and Baxter are both autistic. The pair, shown here working on a poster for the climate strike, find Thunberg's perspective on autism empowering. (Ioanna Roumeliotis/CBC)

For Baxter King, age nine, Thunberg is a role model because of her message, but also because they have much in common.

"She's autistic and I'm autistic so we're sort of, almost, kind of, related to each other."

"I've never heard of anyone being autistic who's famous," he says.

"Yeah, it's pretty cool."

WATCH - From The National, Greta Thunberg's climate marches draw protesters from across the generations: