Desertification and land degradation in arid and semi-arid regions

Abstract

Introduction Land degradation occurring in particular climate zones, i.e. arid, semi-arid, and dry sub-humid areas, is defined as desertification by the United Nations Convention to Combat Desertification (UNCCD, 1999). As desertification is widely viewed as one of the leading environmental issues facing the world today, many individual researchers and international organizations have tried to clarify and to update the definition of this term. Among various conceptions, the ones from the United Nations Authority have been most often used. The earlier definition adopted by the United Nations Environment Programme (UNEP, 1990) was practically the same as the one given by Conacher and Conacher (2000), limiting the cause of degradation to human activities. At the UN Conference on Environment and Development in Rio de Janeiro in 1992, both climatic variations and human activities were accepted as factors triggering desertification (Williams and Balling, 1995). Independent of the exact causes of desertification in each individual case, desertification is a distinct geomorphological hazard due to its impacts on landforms and on geomorphological processes. Among various geomorphological hazards, desertification has been given probably the greatest attention by the United Nations. In 1994 the United Nations Convention to Combat Desertification (UNCCD) was adopted. In 1996 the agreement legally entered into force following its 50th ratification. The year 2006, the 10th anniversary since the UNCCD came into effect, was declared by the United Nations as the International Year of Deserts and Desertification.