Greta Thunberg is an impressive individual. Just 16 years old, she has been nominated for the Nobel peace prize after sparking environmental protests around the planet. There is a glorious simplicity to her arguments that makes them hard to refute. What, she asked, was the point of pupils like her learning anything if politicians ignored the glaring facts on climate change? So she sat down outside the Swedish parliament with a hand-painted banner declaring a school strike – and eight months later, is a global icon who has helped to fire up a resurgent green movement.

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Thunberg’s parents say their daughter, once painfully introverted, was always a bit different to other children. Four years ago, she was diagnosed with Asperger’s, on the autism spectrum, which helps explain her remorseless focus on the core issue of climate change after overcoming depression. “Being different is a gift,” she told Nick Robinson when interviewed on Radio 4’s Today programme. “It makes me see things from outside the box. I don’t easily fall for lies, I can see through things. If I would’ve been like everyone else, I wouldn’t have started this school strike for instance.”

She admitted her passion was partly down to viewing the world in stark terms. The result of her simplistic approach, fuelled by her condition, is that she has presented this issue with more clarity and competence than almost any adult activist or politician in recent years. And there is something rather beautiful in hearing this teenager demonstrate by her actions how society is stronger when it embraces difference – a message that seems so pertinent to our troubled age. Indeed, this aspect of her stance as a now-public figure on the autism spectrum is arguably as important as her bold stand on climate change, given many prevailing attitudes.

Play Video 1:44 Greta Thunberg tells MPs: 'Our future was sold' – video

For we live in a society that, far from respecting difference, often seems to fear or ignore those that stand apart from the crowd. Look at how people with autism and learning disabilities are routinely abused, bullied, excluded from school, swept aside in the jobs market and shunted into the worst housing in the toughest parts of town. Hundreds suffer avoidable deaths in the National Health Service each year due to a lack of training for, or indifference of, medical staff, reflecting the insidious discrimination that corrodes our culture. Note how there is almost no debate over the ethics and implications of a dawning new age of eugenics, despite scientific advances that threaten to eliminate conditions such as Down’s Syndrome.

I have spoken to scores of families of girls with autism like Thunberg. Instead of being feted, these teenagers often end up locked in secure psychiatric units where they are forcibly drugged and violently restrained by adults. Some are shut in solitary confinement, even fed through hatches or with food dumped on the floor like dogs. One mother told me of how her daughter also became impassioned over injustice, focusing on human rights issues with a moral clarity and vigour that drove away friends and freaked out their parents. As her anxieties intensified in adolescence there was inadequate support. She ended up in both NHS- and privately run hellholes, learning self-harm from other patients, secluded and frequently restrained.

Autism is not always a gift. But we need to get beyond labels to see individuals, ensuring everyone has a chance to enjoy as meaningful an existence as possible. Celebrate difference, encourage strength, support weaknesses. For many people with this condition, life can be a constant challenge – yet blinkered attitudes and bigotry means their struggles are made worse. Many end up with criminal records after stresses and meltdowns are misinterpreted and then compounded by being misrepresented. Last month one young woman managed to overturn a conviction for malicious damage and a £1,500 fine after she was arrested, strip-searched and charged with obstruction of a rail carriage for the crime of using a toilet, then panicking when a ticket inspector banged on the door.

There will always be some who sneer and pick on differences. We have seen how Frankie Boyle’s cruel jibes at people with learning disabilities proved no bar to his media career. Perhaps inevitably, given their predictable efforts to be provocative, Spiked published an offensive piece by its editor mocking Thunberg as someone who “looks and sounds like a cult member”, attacking her for “the monotone voice. The look of apocalyptic dread in her eyes.” If only such infantile attention-seekers possessed an ounce of her decency, dignity or maturity. Instead they prefer to mock a courageous teenager with autism speaking in a second language, rather than engage with her arguments.

Thunberg is far from alone in offering lessons on harnessing difference for wider societal benefit. It has been claimed some of the great figures from history were autistic, including Charles Darwin, who transformed our understanding of the planet. Then there is Auticon, an Anglo-German company, which uses the cognitive diversity of staff on the spectrum for data and software development. La Casa de Carlota, a design firm in Barcelona, hires staff with Down’s Syndrome, autism and learning disabilities alongside other designers to utilise their unique approach to creativity.

Yet this teenager’s voice is vital at a time when people with autism are being locked up in costly secure hospitals that only worsen their condition simply for the “offence” of being different, while citizens with learning disabilities clog up prisons and remain banished to the fringes of society. She reminds us not only of the urgent need to confront climate change, but also to tackle the intolerant attitudes that still dismiss far too many people for nonconformity and thinking outside the box.

• Ian Birrell is a former deputy editor of the Independent