Update, Dec. 12: On Thursday, President Trump mocked Greta Thunberg, and she hit back.

Time on Wednesday named the young climate activist Greta Thunberg as its person of the year, in a nod to the next generation’s surging prominence in worldwide efforts to prevent the worst effects of climate change.

It was an irony, perhaps, that the designation, announced on television and online, is a ritual marketing stunt that is one of the last vestiges of an era when weekly print magazines were a major force in the news cycle.

Speaker Nancy Pelosi, President Trump, the Ukraine whistle-blower and the Hong Kong protesters were all on the shortlist for this year’s selection, according to the anchors of the “Today” show.

“I could never have imagined anything like that happening,” Ms. Thunberg told The Associated Press on Wednesday, adding that she was “surprised” by the news.