More than 20 million people in North-East Nigeria, South Sudan, Yemen and Somalia are facing famine or a credible risk of famine over the coming six months. Some 1.4 million children are currently at imminent risk of death from malnutrition. To avert a major humanitarian catastrophe the United Nations and its partners must massively scale up efforts now. To do this, humanitarian operations in the four countries require more than US$5.6 billion in 2017, of which at least US$4.4 billion are required urgently.