Environmental degradation is an essential cause of decreasing agricultural production. Threats to the environment in developing countries in particular are very serious and are mounting. Genetic resources - which should be preserved as sources of future diversity and improvement - are shrinking because of pollution, deforestation, and the neglect of traditional species of crops and livestock. Soil degradation is a major hazard, and the the consequences of soil degradation are drastic: declining productivity of the land, sometimes leading to total loss of productivity, in many cases reversible only at very high cost.
The yields of many African countries are lower today than in 1950, primarily due to erosion. A collaborative study by the United Nations Environment Programme (UNEP) and FAO found that 35% of the land area of North Africa was at risk from water erosion, 17% from wind erosion and 8% from salinization. Comparable figures for the Near East were 22% for water, 12% for wind and 1.4% for salinization. More than one third of the area of developing regions is either existing desert (8 million square kilometres) or at risk of becoming so (37.6 million square kilometres).