The issue of climate change will be the biggest topic of discussion at this year's United Nations General Assembly. UN secretary general, Antonio Guterres has called for members states to bring forward the most innovative and impactful ideas in combatting climate change. He will preside over the Climate Change Action Summit on Monday. But, there is also a youth-led summit that takes place tomorrow. (Saturday 21/09). Noma Bolani reports from New York...