Greta Thunberg tells UK climate strike: 'The world is on fire'

Climate activist Greta Thunberg has warned "those in power" she will "not be silenced when the world is on fire." The teenager was welcomed by chants of "Greta, Greta" as she addressed some 15,000 people at the Bristol Youth Strike 4 Climate (BYS4C) event on February 28th.