Desertification occurs where semi-arid lands bordering deserts lose vegetation and soil fertility due to drought and human activities. The Sahel region in Africa is highly vulnerable to desertification due to its semi-arid climate and experienced periods of drought in the 1970s that caused widespread impacts. Desertification results from both physical processes like soil erosion from wind and water after vegetation dies as well as human factors such as overgrazing, deforestation, and unsustainable agriculture that degrade the soil.