Definition- Desertification is not the natural expansion of existing deserts but the degradation of land in arid, semi arid, and dry sub-humid areas. It is a gradual process of soil productivity loss and the thinning out of the vegetative cover because of human acitivites and climatic variations such as prolonged droughts and floods. What is alarming is that though the land’s topsoil, if mistreated, can be blown and washed away in a few seasons, it takes centuries to build up. Among human causal factors are over cultivation. Overgrazing, deforestation, and poor irrigation practices. Such over exploitation is generally caused by economic and social pressure ignorance, war and drought.
Desertification a Global Problem– Desertification is a worldwide problem directly affecting 250 million people and a third of the earth’s land surface or over 4 billion people who depend on land for most of their needs and usually the world’s poorest in over one hundred countries are threatened.
Though Desertification affects Africa the most, where two- thirds of the continent is desert or drylands, it is not a problem confined to drylands in Africa. Over 30 % of the land in the United States is affected by desertification. One quarter of Latin America and the Caribbean is deserts and drylands. In Spain, one fifth of the land is at risk of turning into deserts. The growing severity of the threat in the Northern Hemisphere is also illustrated by severe droughts in the United States and water scarcity in southern Europe. In China, since the 1950s, sand drifts and expanding deserts have taken a toll of nearly 700,000 hectares of cultivated land, 2.35 million hectares of rangeland, 6.4 million hectares of forests, woodlands and shrub lands. Worldwide some 70 % of the 5.2 billion hectares drylands used for agriculture are already degraded and threatened by desertification.
Causes of Desertification- Desertification comes mainly from variations in climate and human activities, but many other causes can interact to create conditions, likely to lead to Desertification. These include the movement of refugees during periods of conflict, inappropriate land use or environmental management, specific socio-economic and political factors.
Climatic variations- high temperatures lasting for months create droughts that prevent the vegetation from growing.
Human Activities- leading to Desertification are mainly related to agriculture:
Overgrazing removes the vegetation cover that protects it from erosion.
Over cultivation exhausts the soil deforestation destroys the trees that bind the land to the soil. Wood is the principal source of domestic energy for lighting and cooking in many arid areas.
Poor irrigation practices raise salinity, and sometimes fry the rivers that feed large lakes: the Aral Sea and Lake Chad have shrunk dramatically in this way.
Impact of Desertification
Desertification affects all aspects of life, highlighting how much environment and livelihoods are interlinked.
Environmental Impacts- because of the vegetation loss, Desertification makes areas more flood prone. It also cause the salt level in soil to rise, results in deteriorating quality of water, and silting of rivers, streams and reservoirs.
Economic Impacts- Desertification has huge economic consequences- the World Bank estimates that at the global level, the annual income foregone in the areas affected by desertification are forced to move elsewhere to find other means of livelihood. Usually they migrate towards urban areas or go abroad. Mass migration is a major consequence of desertification.
Restore and fertilise the land- A simple and cheap way to fertilise the land is to prepare compost, that will become humus and will regenerate the soil with organic matter.
Combat the effects of the wind- by constructing barriers and stabilising sand dunes with local plant species.
Trees play several roles: they help fix the soil, act as wind breakers, enhance soil fertility, and help absorb water during heavy rainfall. Because the burning of land and forests increases dangerous greenhouse gases, afforestation-planting new trees- can he;p reduce the negative impacts of resulting climate change.