After hitching a ride from the US three weeks ago, Greta Thunberg has arrived in Europe in time for the UN climate conference, COP25.

The climate activist docked in Lisbon on Tuesday, telling cheering crowds on arrival that the journey “energised” her in the fight against the climate crisis. After a few days in Portugal, the 16-year-old will head to Madrid for the conference, which was originally set to take place in Chile.

“We’ve all been on quite an adventure,” Thunberg told reporters. “It feels good to be back.” The teen travelled with her father, an Australian family, and a professional sailor on a yacht powered by solar panels and hydro-generators. “I am not travelling like this because I want everyone to do so,” the teen explained. “I’m doing this to send the message that it is impossible to live sustainably today, and that needs to change.”

After spending three weeks at sea, Thunberg was pleased to be back on land, writing on Twitter: “Change of scenery! I probably look a bit drunk, stumbling around the beautiful streets of Lisboa (sic) on my sea legs… Now I will spend a couple of days climbing up from the rock I’ve been living under the last three weeks, trying to catch up with the world.”

The activist initially arrived in the US after setting sail in August, and joined global climate strikes in New York, as well as giving a passionate speech at the UN climate summit in September. After feuding with Donald Trump, declining an environmental prize, and meeting Leonardo DiCaprio, Thunberg had to urgently seek transport back to Europe after COP25 was relocated from Chile.

Having faced unwarranted criticism from right-wing figures during her time in the US, the teenager addressed their comments as she docked in Lisbon. “I think people are underestimating the force of angry kids,” she said. “If they want us to stop being angry, then maybe they should stop making us angry.”