This factsheet about land degradation was published by UNEP, and provides a helpful overview of the challenge. You can download it by clicking here.
Healthy landscapes are fundamental to the health of life on earth. From food production to quality air and water, nutrient cycling and soil formation, we depend on our land for the very basics of existence. Land degradation and desertification, largely due to deforestation and unsustainable land use, are amongst the most pressing problems facing the world today. UN Environment, working in partnership with the Global Environment Facility (GEF), aims to be part of the solution to this problem. Together, we have worked on more than 160 projects, promoting sustainable land management practices and helping countries around the world to restore degraded land.
Link to the factsheet: https://www.unep.org/resources/factsheet/land-degradation-factsheet