Nigeria's election includes three main presidential candidates.

On Saturday, voters in Nigeria will decide who will succeed President Muhammadu Buhari as the leader of Africa’s most populous country and largest economy. While eighteen candidates are running, there are three top contenders, all of whom are wealthy, card-carrying members of the political establishment.

In Africa, the Great Green Wall aimed at combating Sahel desertification and climate change is largely considered a failure.

In 2007, the African Union launched the Great Green Wall project, an attempt to combat expanding desertification in the Sahel by planting a barrier of trees 10 miles wide across 4,500 miles by 2030. But the wall has so far produced disappointing results and shows the complexities of implementing a grand continent-wide scheme.

In Nigeria, politics and security is in crisis after the eight years of President Buhari.

This weekend’s African Union leaders’ summit in Addis Ababa, Ethiopia, will be Nigerian President Muhammadu Buhari final one ahead of his departure from office in May. Haunting Buhari’s final AU summit, and his last months in office, is a grim reality: Nigeria’s continued decline as a continental power.