The 16-year-old first hit the headlines for her solo strike against global warming outside Sweden's parliament last year.
“We can't just continue living as if there was no tomorrow, because there is a tomorrow. That is all we are saying,” Thunberg told Time.
The magazine interviewed Thunberg aboard the sailboat that took her from the United States to Europe after a hectic 11-week North American trip to several US cities and Canada.
Thunberg has taken her disarmingly straightforward message — “listen to the scientists” — to global decision-makers, accusing them of inaction.
The Swedish activist was in Madrid as the award was announced, at a UN climate forum tasked with saving the world from runaway global warming.
“The politics of climate action are as entrenched and complex as the phenomenon itself, and Thunberg has no magic solution,” Time wrote in the interview.
“But she has succeeded in creating a global attitudinal shift, transforming millions of vague, middle-of-the-night anxieties into a worldwide movement calling for urgent change.
“She has offered a moral clarion call to those who are willing to act, and hurled shame on those who are not.”