Climate Action: Greta Thunberg's mission

The Swedish teenage activist Greta Thunberg explains how she aims to get the world's governments gathered for the UN Climate Action Summit in New York to take meaningful action on global warming. Justin Rowlatt speaks to her about her ambitions for her transatlantic trip, and whether one person can really make that much of a difference. In order for her mission to succeed, it will mean rebuilding the global economy from the ground up, including the phasing out of most of the oil and gas industry. John Hofmeister, the former president of Shell's US subsidiary, claims the big oil companies are ready and willing to do their part, if the politicians will only give them the green light. Producer: Laurence Knight (Picture: Greta Thunberg testifies at the US Congress in Washington DC; Credit: Alex Wong/Getty Images)