Environmentalists Wish Greta Thunberg 'Bon Voyage' as She Sails Back from U.S. to Europe: 'Safe Travels'

Teenage environmentalist Greta Thunberg is hitching a ride on a catamaran to cross the Atlantic Ocean which she hopes will arrive in Spain in time for a United Nations global climate meeting.

The 16-year-old Swede has drawn crowds wherever she has gone in North America after her impassioned address at the United Nations Climate Action Summit in September.

Shunning air travel because of its high levels of emissions, she had intended to cross overland to Chile where the U.N. conference was originally going to be held, before it was shifted to Madrid due to anti-government protests in Santiago.

In response to her appeal to head back to Europe, Australian couple Riley Whitelum and Elayna Carausu, who have a large following on YouTube, had offered Thunberg a place aboard their 48-foot catamaran called La Vagabonde, which is powered by solar panels and hydro-generators.

Thunberg wrote on Instagram: "So happy to say that I'll hopefully make it to COP25 in Madrid. I've been offered a ride from Virginia on the 48ft catamaran La Vagabonde."

Her travels across North America have been given a rousing welcome and her send-off has been equally as warm. Environmentalist and founder of 350.org Bill McKibben tweeted to his 324,000 followers: "Bon voyage @GretaThunberg—what a pleasure it has been to have you on this continent! And what great organizing you've done!"

Meanwhile, climate activist Jamie Margolin tweeted to her 25,000 followers: "It was wonderful having you in the United States @GretaThunberg, safe travels to Spain and beyond."

On the return voyage to Europe, Thunberg will be joined by a British professional sailor, Nikki Henderson and her father, Svante as well as the Australian couple's 11-month-old son, according to The New York Times.

"We just said yes straight away because we just did a big 10-day sail and we loved it so much and we're pretty keen for another adventure like this," Carausu told CNN.

Carasu said that Thunberg has been helping them get the vessel ready for the 3,200 nautical mile trip, telling CNN: "She looks like a little girl but her personality—she's really independent, she knows what she wants and she's really sweet and really helpful."

Thunberg's fame has grown quickly in the U.S. where a collection of her speeches has been released in an anthology by Penguin Press.

Her face has also been painted on a mural on the side of a building in San Francisco. A meme of her giving a cold stare to President Donald Trump, who had mocked her, went viral.

She also appeared on The Daily Show, rode a bike with Arnold Schwarzenegger and protested with Sioux leaders in North Dakota.

"Traveling around is very fun and I'm very privileged to have the opportunity to do so, but it would be nice to get back to my routines again," Thunberg told The Times.