Greta and her PR team do not publish details of her carbon footprint, so I don't have exact details her travels but Wikipedia is a fairly reliable source to give some insight.
The word "emergency" occurs once, in phrase "Thunberg does not fly except for emergency cases.(4)" . The link (4) leads to https://time.com/5663534/greta-thunberg-arrives-sail-atlanti... "Climate Activist Greta Thunberg, 16, Arrives in New York After Sailing Across the Atlantic" . I didn't read the whole article, are you saying that article says Thunberg flies?
Sorry, I'm not sure where the wikipedia Editor got that information from. I can change my original comment to "travels with a significant carbon footprint" if you would make you happy? Does the carbon footprint section of wikipedia seem up to your standards?
From what I know about Greta, she is rather careful with such matters. Your comment in general is in effect destroying part of those careful efforts, so I'd be happy if it wouldn't.
"Significant carbon footprint" asks for, significant compared to what? Maybe Greta leaves bigger footprint than the lowest, say, 10% of the Earth population, who don't really have access to modern technologies with that significant footprint. But she surely tries quite a lot given the circumstances where she is, and encourages us to follow. So I'm skeptical about accusations towards her without enough evidence.