Desertification & the Sahel: Causes & Solutions
What Is Desertification?
Desertification is the process by which fertile land turns into desert. It does not mean sand dunes invading farmland; rather, it means soil losing its productivity until crops will no longer grow. Around 12 million hectares of land are lost to desertification every year — an area about the size of England. The places most at risk are semi-arid regions on the fringes of existing deserts, where rainfall is already low and unreliable.
The Sahel: Africa's Front Line
The Sahel is a band of dry grassland running across Africa just south of the Sahara, from Senegal in the west to Sudan in the east. Around 100 million people live there. Rainfall averages 100–600 mm a year and is highly seasonal — so a single bad rainy season can devastate harvests. The Sahel has been desertifying for decades, and the population has tripled since 1960, increasing pressure on the land.
The Sahel is a semi-arid belt across Africa, south of the Sahara, with 100 million people and 100–600 mm of rain a year. It has been desertifying for decades.
Causes of Desertification
Desertification has several interlocking causes — climate change driving the trend, and human activity making it worse on the ground.
- Climate change. Rising temperatures increase evaporation. Rainfall patterns are shifting; some Sahel regions have seen 25% less rain than in the 1950s.
- Population growth. More people means more food needed, more cattle, more firewood, more pressure on the same land.
- Removal of fuelwood. Trees are felled for cooking and heating fuel. Without their roots, soil washes or blows away.
- Overgrazing. Too many cattle or goats strip vegetation faster than it can regrow.
- Over-cultivation. Farming the same field continuously without rest exhausts the soil's nutrients.
- Soil erosion. When vegetation is gone, wind and rain remove the topsoil, sometimes in a single dust storm.
Desertification is rarely caused by one thing. A drought makes farmers move their cattle further; the cattle overgraze the new area; vegetation thins; the soil loses its grip; the next storm washes the topsoil away; the land can no longer support the cattle, so the farmers move again, repeating the cycle. Each step makes the next one worse. Climate change is now adding background pressure to a system already under strain.
Reducing the Risk
Solutions target both the land and the people who farm it. Strategies fall into four broad groups.
- Water and soil management. Magic stones (lines of stones along contours) trap rainwater and let it soak in. Mulching with crop residues holds moisture in soil. Bunds (low earth banks) slow runoff.
- Tree planting. Roots bind soil. Trees shade crops and reduce evaporation. The most ambitious project is the Great Green Wall (see below).
- Appropriate technology. Locally-made drip-irrigation, fuel-efficient stoves (using less wood) and treadle pumps for water make farming sustainable without expensive equipment.
- Rotation and reduced livestock. Letting fields rest, rotating crops, reducing herd sizes — all give the land a chance to recover.
Desertification can be reduced through water and soil management (mulching, bunds), tree planting (Great Green Wall), appropriate technology (drip irrigation, efficient stoves) and reduced grazing pressure.
The Great Green Wall
The Great Green Wall is a flagship African Union project. The plan: plant a belt of trees and vegetation nearly 8,000 kilometres long right across the Sahel, from Senegal to Djibouti, to halt the southward spread of the Sahara. Launched in 2007, it has been complicated. Some early plantings failed because the wrong species were used. Progress is uneven across the 11 participating countries. By 2024, only around 18% of the planned area had been restored, but the project has shifted approach — now focusing on a 'mosaic' of tree planting, soil restoration and farm land management rather than a single continuous line of forest. It is now estimated that fully delivering the Wall would create 10 million jobs and lock up 250 million tonnes of carbon.
Scale, funding and conflict have all slowed it down. Trees planted in the wrong soil at the wrong time die quickly. Funds promised by donors have not always arrived. Local conflict in Mali, Burkina Faso and Niger has made some areas dangerous to work in. Crucially, the project depends on local farmers, not international planters — and farmers need to see real benefit from the trees (firewood, fodder, soil improvement) to maintain them.