Even though it is slow, the pace is picking up and the debate is shifting, 16-year-old Swedish climate activist Greta Thunberg tells a rapturous audience at George Washington University. Thunberg pioneered the Fridays for Future school climate strikes in August last year by staging a solo protest outside the Swedish parliament. The movement has since grown around the world. The next mass protest is on 20 September. 'Activism works', she says, before concluding: 'See you on the street!'