Explanation:
"The haters are as active as ever", the 16-year-old Swedish climate activist posted on social media on Thursday, "going after me, my looks, my clothes, my behaviour and my differences". Anything, she says, rather than talk about the climate crisis.
It hasn't stopped her from campaigning. On Friday, she led another of her climate strikes, heading up a huge demonstration in Montreal, demanding international aviation does more to cut its carbon footprint.
But she is clearly very annoyed, accusing critics of "crossing every line to avert the focus" with, what she calls, lies and conspiracy theories.
Of course, the attention isn't surprising. Over the past year, Greta Thunberg has arguably done more to galvanise global action on climate than any other single individual.
And there is no question the unnerving power of her rhetoric comes in part from the fact that she is so young.
Thunberg to leaders: 'You've failed us on climate'
UN panel signals red alert on 'Blue Planet'
Climate change 'accelerating', say scientists
Content is not available
A key reason her "How dare you!" message hit home so hard in the UN this week was because she seemed so jarringly out of place in the air-conditioned formality of the UN's New York HQ.
It is unusual for young people to hold the adult world to account so forcefully and so publicly and some people clearly don't like it.
She certainly did that on Monday when she accused world leaders of "stealing my dreams and my childhood", and warned them that "the eyes of all future generations are upon you. And, if you choose to fail us, I say: 'We will never forgive you'".
So, how about her mental health? And, while we're about it, does anyone have the right to comment on it? What's so impressive about Thunberg is how clear-headed she is on the urgent need for action in the light of the science.
Understandably, Thunberg particularly resents her mental capacity being called into question. "Being different is not an illness and the current, best available science is not opinions - it's facts", she said this week.
She acknowledges that she was very unhappy in the past, but says that championing the climate issue has helped lift her out of despair.
"It makes me feel good that I'm not alone in this fight," she told me, "and it feels like my life has some kind of meaning lately and I feel that what I am doing is meaningful."
She's famously described her Asperger's as a "superpower", allowing her to cut through the noise and see to the heart of the issue.
Media caption"You are failing us" - Greta tells world leaders
Dr James Cusack, director of science at the autism charity, Autistica, says she's been a really important role model for others with the condition. "Her brave, clear-minded and science-led approach to activism is inspiring for many people," he says.
And, while Thunberg is sometimes emotional about her cause she says that's because she's appalled and frustrated that the world isn't doing enough to tackle climate change.
She has the full support of her family. Her father, Svante Thunberg, is travelling in America with her - and shared the privations on her transatlantic voyage. Her mother and younger sister, Beata, stayed in Sweden.
She's no plans to stop campaigning any time soon.
These coming months are crucial, she told me, if the world is going to manage to keep the global temperature increase below 1.5 degrees above pre-industrial levels. Emissions have to start reducing before the end of next year, she warns, or we are likely to pass tipping points leading to uncontrolled climate change.
Yet, last year global carbon emissions increased by 2.7%, hitting a record high of 37.1bn tonnes.
Thunberg was upset by the response of the world leaders in the UN HQ this week. They politely applauded her speech but had no new initiatives that would significantly reduce greenhouse gas emissions, and most also failed to acknowledge either her message or the fact that millions of people had taken to the streets to demand action just days before.
So, climate action remains very much a work in progress for Thunberg, despite her critics.
"I guess they must feel threatened by us," she wrote this week. "But the world is waking up."
