The Great Green Wall

The Great Green Wall is a plan to hold back the expansion of the Sahara with an 8000 km natural wonder of the world across the width of Africa. It would be the largest living structure on the planet.

In Burkina Faso, a landlocked country between Mali and Ghana, a hot dry wind from the Sahara blows. The north of the country is in the Sahel, the borderland of the Sahara. Its temperatures range up to 47°C and it gets less than 600mm of rainfall a year. There, Ecosia, the eco-friendly search engine, has planted nearly 17m trees over 12,400 hectares.

Chad has planted 1.1m seedlings, and its nickname “the dead heart of Africa” could be made obsolete. Africa’s second largest wetland, 17,806 square km Lake Chad, was once 330,000 square km in the Chad Basin, which does not drain to the sea. Increasing water shortages contribute to the rise of Boko Haram in the region. Part of it is Sahel acacia savannah, which once supported vast migrating herds of grazing mammals.

Mauritania was part of the original Panafrican Agency of the Great Green Wall in 2007. The UN Convention to Combat Desertification proposed 1.65 million hectares of forest there. In January 2021 its president, Mohamed Cheikh El-Ghazouani, who is the chair of PAGGW, welcomed the UN’s Accelerator programme, a new $14bn scheme. It is estimated that $33bn investment is needed to complete the wall.

Though 80% or more of planted trees in the Sahara die, in Niger, farmers used water harvesting techniques to protect trees that seeded naturally on their farms. Rather than planting a forest on the edge of a desert, the project transformed to develop indigenous land use techniques. Hundreds of thousands of farmers made the land productive for food and fuel for 3m people. French imperialism had imposed French techniques, to clear land for agriculture and keep crops separate from trees, damaging the ecology. The trees improve the soil. Twelve million acres in Niger were restored for farming.

South Sudan is south of the area of the Wall, which passes through Sudan. In South Sudan, the breakdown of agriculture foments conflict. It is covered in tropical forest, swamps and grassland, 3° north of the Equator.

Western Sahara is occupied by Morocco after liberation from Spanish rule in 1975. It has no permanent streams, and in summer reaches 45°C. Yet its north-west, with the temperature moderated by the Atlantic Ocean, has Acacia dry woodlands and succulent thickets.

Global Citizen gives a good introduction. The wall aims to

• improve soil quality for farmers, which would allow crops to better withstand hostile conditions;
• create wildlife corridors that revitalize ecosystems and become hubs of tourism;
• restore sources of water to combat drought;
• generate millions of green economy jobs;
• establish a carbon sink to fight climate change;
• break the vicious cycles of migration that are draining societies of youth;
• boost economies;
• and ease the conditions that lead to violence.

Kew Gardens are involved in Burkina Faso, Mali and Niger, planting one million seedlings over four years, collecting and storing species and investigating which survive best.

Here is the project website.