For those of you who would like a little more info before you decide whether or not you are going to watch a video, Greta Thunberg is a 15-year-old Swedish schoolgirl who started striking last year (staying away from school to sit outside the Swedish parliament with a sign calling for climate action) to appeal to Swedish politicians to do more for the climate of the Earth. Her ongoing strike has inspired young people in other countries to do the similar things to appeal to politicians to do more to save the climate of the Earth.
In the video posted by Art, she is giving a TED talk.
In Sweden, Greta Thunberg is also famous because her mother, Malena Ernman, is a popular singer.