Few climate adaption projects can match the sheer ambition — or unfullfilled promise — of Africa’s “Great Green Wall.”
The United Nations-backed initiative, launched in 2007, aims to plant a 5,000-mile belt of trees across Africa’s Sahel region from Senegal in the west to Djibouti in the east.
If successful, the human-constructed forest would sprawl across 603,000 square miles…
