In the countries involve by desertification problems
seem to never give up: in fact consequences are also very important for people
living there and, what is worst, they persist for many years.
Desertification reduces the land's
resilience to natural
climate variability. Soil, vegetation, freshwater supplies, and other dryland
resources tend to be resilient. They can eventually recover from climatic
disturbances, such as drought, and even from human-induced impacts, such as
overgrazing. When land is degraded, however, this resilience is greatly
weakened.
- This has both physical and socio-economic
consequences.
Soil becomes less productive [ES1] Exposed and eroded topsoil can be
blown away by the wind or washed away by rainstorms. The soil's physical
structure and bio-chemical composition can change for the worse. Gullies and
cracks may appear and vital nutrients can be removed by wind or water. If the
water table rises due to inadequate drainage and poor irrigation practices, the
soil can become waterlogged, and salts may build up.
- Soil looses its ability to support plant growth and
to hold moisture, resulting in increased evaporation and surface run-off.
Vegetation becomes damaged. The loss of vegetation cover is both a consequence
and a cause of land degradation. Vegetation changes because pastures are
overgrazed by too many animals or by inappropriate types.
- Edible plant species can be lost, allowing inedible
species to invade.
Some of the consequences are borne by people living
outside the immediately affected area. Degraded land may cause downstream
flooding, reduced water quality [E1] [E2] [E3] [ES1] [F1], sedimentation in rivers and lakes,
and siltation of reservoirs and navigation channels.
It can also cause dust storms and air pollution
[ES1], resulting in damaged machinery,
reduced visibility and unwanted sediment deposits. The dust can also worsen
health problems, including eye infections, respiratory illnesses,
and allergies.
Food production is undermined. Desertification is considered a major
global environmental issue largely because of the link between dryland
degradation and food production. A nutritionally adequate diet for the world's
growing population implies tripling food production over the next 50 years. This
will be difficult to achieve even under favourable circumstances. If
desertification is not stopped and reversed, food yields in many affected areas
will decline. Productivity is affected by many different factors, such as the
weather, disease and pests, farming methods, and external markets and other
economic forces.
Desertification contributes to
famine. Famine [F1] [ES1] [I1] typically occurs in areas that also suffer from
poverty, civil unrest, or war. The relationship between soil degradation and
crop yields is seldom straightforward. In fact, drought and land degradation
often help to trigger a crisis, which is then made worse by poor food
distribution and the inability to buy what is available.
- Malnutrition, starvation, and ultimately famine may
result.
Desertification has enormous social
costs. There is now
increased awareness of the relationship between desertification, movements of
people, and conflicts. In Africa, many people have become internally displaced
or forced to migrate to other countries due to war, drought, and dryland
degradation. The environmental resources in and around the cities and camps
where these people settle come under severe pressure.
- Difficult living conditions and the loss of cultural
identity undermine social stability.
Desertification is a huge drain on economic
resources. [E1] There is little detailed data on the economic
losses resulting from desertification, although an unpublished World Bank study
suggested that the depletion of natural resources in one Sahelian country was
equivalent to 20% of its annual Gross Domestic Product (GDP). The indirect
economic and social costs suffered outside the affected areas, including the
influx of "environmental refugees" and losses to national food production, may
be much greater.
