Greta Thunberg is to sail across the Atlantic in a high-speed racing yacht next month to attend UN climate summits in the US and Chile as part of a sabbatical year the 16-year-old Swedish climate activist will spend in the US.

“Good news! I’ll be joining the UN Climate Action Summit in New York, COP25 in Santiago … I’ve been offered a ride on the 60ft racing boat Malizia II. We’ll be sailing across the Atlantic Ocean from the UK to NYC in mid August,” Greta tweeted. The journey will take two weeks.

The campaigner, whose solo protest last year sparked the Fridays for Future global school climate strike movement, said in June she would be taking a year off school to attend the summits, on 23 September in New York and 2-13 December in Santiago, which she described as “pretty much where our future will be decided”.

But she said she did not yet know how she was going to get there. “It’s on the other side of the Atlantic Ocean,” she said. “And there are no trains going there. And since I don’t fly, because of the enormous climate impact of aviation, it’s going to be a challenge.”

Profile Who is Greta Thunberg? Show Hide 'Never too small to make a difference' In August 2018 Thunberg began a solo climate protest by striking from school in Sweden when aged 15. She has since been joined by tens of thousands of school and university students in Australia, Belgium, Germany, the United States, Japan and more than a dozen other countries. 'Irresponsible children' Speaking at the United Nations climate conference in December 2018, she berated world leaders for behaving like irresponsible children. And in January 2019 she rounded on the global business elite in Davos: “Some people, some companies, some decision-makers in particular, have known exactly what priceless values they have been sacrificing to continue making unimaginable amounts of money. And I think many of you here today belong to that group of people.” Inspiration Veteran climate campaigners are astonished by what has been achieved in such a short time. Thunberg has described the rapid spread of school strikes for climate around the world as amazing. “It proves you are never too small to make a difference,” she said. Her protests were inspired by US students who staged walk-outs to demand better gun controls in the wake of multiple school shootings. Family Her mother, Malena Ernman, has given up her international career as an opera singer because of the climate effects of aviation. Her father is actor Svante Thunber. Greta has Asperger’s syndrome, which in the past has affected her health, he says. She sees her condition not as a disability but as a gift which has helped open her eyes to the climate crisis. Photograph: Michael Campanella/CampanellaFoto

Owned by a German property developer, Gerhard Senft, based in Brittany and sponsored by the Yacht Club de Monaco, the 18-metre (60ft) yacht is a high-speed planing monohull built for the 2016-17 single-handed, non-stop round-the-world Vendée Globe race. The club said on its Facebook page it was “honoured to be able to sail Greta Thunberg emission-free over the Atlantic”.

Facebook Twitter Pinterest The Malizia in Saint-Tropez Photograph: Arnold Jerocki/Getty Images

The yacht is fitted with solar panels and underwater turbines to generate zero-carbon electricity. Greta will be accompanied on the voyage by Malizia II’s skipper Boris Hermann, her father Svante, Pierre Casiraghi, the grandson of Monaco’s late Prince Rainier III and the actor Grace Kelly, and a film-maker.

Greta told the Associated Press before the announcement that she had not wanted to travel to the US by cruise ship because of their notoriously high emissions, while the Atlantic could be dangerous for sailing boats in August because of the high risk of hurricanes.

“Taking a boat to North America is basically impossible,” she said. “I have had countless people helping me, trying to contact different boats.”

In a joint Guardian interview with the US congresswoman Alexandria Ocasio-Cortez in June, Greta said of her planned visit to the UN climate summit: “I don’t fly for climate reasons so it’s not 100% yet, but we are figuring it out. It’s very hard, but I think it should be possible.”

Referring to her congressional district, Ocasio-Cortez said: “If you land in New York, we will give you a Queens welcome!”

After New York, where she will take part in several meetings and protests, Greta aims to travel by train and bus to the annual UN climate conference in Chile with stops in Canada, Mexico and other countries.

The activist, the daughter of an actor and an opera singer, has spoken to policymakers at last year’s UN climate conference in Poland, to business leaders at the World Economic Forum in Davos, and politicians including the French and British parliaments. She has also met Pope Francis.

Greta, who has encountered fierce criticism from climate deniers and some politicians, told AP she was not sure how her message would go down in the US, where Donald Trump leads broad opposition to the radical measures scientists say are required to limit global warming.

She said meeting the US president would probably be “just a waste of time”, adding: “I have nothing to say to him. He obviously doesn’t listen to the science and the scientists. So why should I, a child with no proper education, be able to convince him?”

This weekend, British Vogue said that Meghan, Duchess of Sussex, would be guest editor of its September issue and had chosen Greta as one of 15 women it described as the “trailblazing changemakers” who would feature on the cover.