Designed for advanced level secondary students, this geography text studies desertification, the encroachment of arable land by desert which threatens an estimated 35% of the Earth's land surface. It explains the causes of desertification, how it can be measured and combatted, and questions whether the situation is actually happening at the scale suggested. The author focuses on questions that have made desertification a major issue, and highlights the difficulties involved in dealing with such a broad-scale physical and social topic. Case study material and exercises are included in the text.