The first internationally recognized definition of the term desertification is due the UNCOD (United Nations Conference on Desertification), in 1977, which stated it was “the diminution or destruction of the biological potential of land, and can lead ultimately to desert-like conditions”

The UNCCD (United Nation Convention to Combat Desertification), approved in Paris on the 17th June 1994 has more accurately defined desertification as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities.

 

 

Land degradation, according to the same Convention, means “reduction or loss, in arid, semi-arid and dry sub-humid areas, of the biological or economic productivity and complexity of rainfed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as: soil erosion caused by wind and/or water; deterioration of the physical, chemical and biological or economic properties of soil; and long-term loss of natural vegetation”.
So, desertification does not necessarily means the expansion of deserts (which is in fact called desertization), but land degradation in specific climatic and human conditions. In the last decades the international community has recognized desertification as one of the major economic, social and environmental troubles affecting most countries in the world. In fact, desertification leads to the loss of soil fertility and, by consequence, of the capability for an ecosystem, especially in desert and semi-desert condition, to produce services. After the Convention on Biological Diversity (June 1992), and especially the Millenium Ecosystems Assessment commissioned by the Secretary-General of the United Nations Kofi Annan in 2000, the ecosystem services have been considered as a concern for human well-being especially for the well-being of the poorest Countries. The ecosystem services generally consist of the following aspects:
•    Provisioning: food, water, fiber and fuel
•    Regulating: climate, water quality, disease
•    Cultural: spiritual, aesthetic, recreation
•    Supporting: primary production, soil formation

Unfortunately, despite the efforts made at international level to combat desertification, the United Nations Environment Programme (UNEP) concluded in 1991 that the problem of land degradation in arid, semi-arid and dry sub-humid areas had intensified, although there were "local examples of success". The Global World Atlas of Desertification (1992) has summarized the state of scientific knowledge on the drylands of the globe representing, in graphical form, the United Nations Environment Program's quantification of the global extent and severity of desertification.

The UNCCD came into being in December 1996, 90 days after the fiftieth Country had signed it.  The first Conference of the Parties was kept in October 1997 in Rome. At the 1st June 2004, the signing Countries of the Convention were 191.