Today she is speaking at the British Parliament.
Teenage environmental activist Greta Thunberg has urged British politicians to "listen to the science" on climate change.
The 16-year-old told BBC Radio 4's Today programme that she did not expect to change their minds single-handedly, saying: "We need to do that together."
The Swedish teenager, who came to London to speak at the Extinction Rebellion environmental protests, and was due to address activists at Parliament Square later on Tuesday, met Jeremy Corbyn, the Liberal Democrat leader, Vince Cable, Green MP Caroline Lucas and the Westminster leaders of the SNP and Plaid Cymru, Ian Blackford and Liz Saville Roberts.
Thunberg – who praised the work of Extinction Rebellion – said her message for politicians was: "Listen to the science, listen to the scientists. Invite them to talk.
"I am just speaking on behalf of them, I'm trying to say what they've been saying for decades," she said.
“A great number of politicians have told me that panic never leads to anything good, but when your house is on fire, then that does require some level of panic,” she said.
"But when your house is on fire and you want to keep your house from burning to the ground, then that does require some level of panic."
The teenager sparked an international youth movement after she staged a "School Strike for Climate" in front of the Swedish Parliament in August last year. This subsequently kicked off the #FridaysforFuture movement which saw secondary school students the world over lobby for climate action on Fridays.
Since then she has met Pope Francis and addressed the European Parliament. Speaking about her newfound fame, she said: "It's unbelievable, I can't really take it in."
Thunberg, who says she gave up flying in 2015, travelled for two days by train to reach the UK.