The leaders of the world's 19 largest economies and two international bodies gathered in Rio de Janeiro in Brazil for the G20 summit, the last meeting before South Africa assumes the presidency. Talks on global challenges like poverty, hunger and climate change are being complicated by the spectre of the incoming US president's isolationist foreign policy plans and his opposition to many of the summit's aims. Ernest Ntimbane spoke to University of Johannesburg's International Relations expert - Ndzalama Mathebula