Desertification

1. What is desertification?

Present-day Drylands

Desertification refers to the persistent degradation of dryland ecosystems by climatic variations and human activities. It occurs on all continents (except Antarctica) and affects the livelihoods of millions of people, including a large proportion of the poor in drylands.

The U.N. Convention to Combat Desertification (UNCCD) defines it as “land degradation in arid, semiarid and dry subhumid areas resulting from various factors, including climatic variations and human activities.” Land degradation is in turn defined as the reduction or loss of the biological or economic productivity of drylands.

In 2000, drylands, which occupy 41% of Earth’s land area, were home to a third of the human population, or 2 billion people.

Ecosystem services are the benefits obtained by people from ecosystems, for instance crops, forage and wood. In drylands, water scarcity limits the production of such services provided by ecosystems. Persistent, substantial reduction in the provision of ecosystem services as a result of water scarcity, intensive use of services, and climate change is a much greater threat in drylands than in non-dryland systems. Areas most vulnerable to desertification are the sub-Saharan and Central Asian drylands.

Desertification occurs as a result of a long-term failure to balance human demand for ecosystem services and the amount the ecosystem can supply. The pressure is increasing on dryland ecosystems for providing services such as food, forage, fuel, building materials, and water which is needed for humans, livestock, irrigation, and sanitation. This increase is attributed to a combination of human factors (such as population pressure and land use patterns) and climatic factors (such as droughts). While the global and regional interplay of these factors is complex, it is possible to understand it at the local scale.

Some 10 to 20% of drylands are already degraded, and, if no countermeasures are taken, desertification will threaten future improvements in human well-being and possibly even reverse gains in some regions. Therefore, desertification is one of the greatest environmental challenges today and a major barrier to meeting basic human needs in drylands. More...