Environmental activist Greta Thunberg said she lacks the power to change US President Donald Trump’s scepticism over global warming as the teenager set sail in a zero-emissions yacht for New York.
The 16-year-old, who inspired strikes around the world in protest at climate change, is travelling to a UN summit next month from Plymouth, southern England.
She said she would continue “to do everything I can” in the fight against global warming despite the many people who claim climate change is not happening.
Asked if she could get Mr Trump to listen to her considering how many world leaders she had met, Ms Thunberg said “no”.
"I'm not that special. I can't convince everyone. Instead of speaking to me and to school striking children and teenagers they should be talking to actual scientists and experts in this area,” she told a press conference before her departure.
Ms Thunberg said her focus was on getting the people in power to react and respond to climate change.
"There's always going to be people who don't understand or accept the united science, and I will just ignore them, as I'm only acting and communicating on the science,” she said.
"I'm just going to do what I want to do and what will have most impact."
Her journey to New York should take around two weeks and she will be accompanied by a filmmaker and her father Svante. Refusing to travel by air, the teenager had never sailed before this week and got seasick on their first journey out of Plymouth on Monday,
The 18-metre yacht is skippered by Pierre Casiraghi, vice president of the Monaco Yacht Club and a member of the principality's ruling family, and German round-the-world sailor Boris Herrmann.