Why is a Great Green Wall being built across Africa?

Available for over a year

A 5,000-mile long line of vegetation is being planted between Dakar in west Africa and Djibouti in the east. Monique Barbut of the UN says its main purpose is to improve conditions for millions of people who do not have a secure source of food. (Image: Culturing young Acacia trees in the Kolya Alfa nursery in Senegal, Credit: BBC.)