DESERTIFICATION

1. DESERTIFICATION TANYA, YEAR 11, GEOGRAPHY

2. WHAT IS DESERTIFICATION? • Desertification is the deterioration of land in arid and dry sub-humid areas, resulting primarily from man-made activities and influenced by climatic variations. • It is principally caused by overgrazing, over drafting of groundwater and diversion of water from rivers for human consumption and industrial use, all of these processes fundamentally driven by overpopulation.

3. Lake Chad in a 2001 satellite image, with the actual lake in blue. The lake has shrunk by 95% since the 1960s.

4. IMPACTS • A major impact of desertification is biodiversity loss and loss of productive capacity, for example, by transition from land dominated by shrublands to non-native grasslands. • In the semi-arid regions of southern California, many coastal sage scrub and chaparral ecosystems have been replaced by non-native, invasive grasses due to the shortening of fire return intervals. This can create a monoculture of that cannot support the wide range of animals once found in the original ecosystems. • In Madagascar’s central highland plateau, 10% of the entire country has been lost to desertification due to slash and burn agriculture by indigenousness people. • In Africa, if current trends of soil degradation continue, the continent will be able to feed only 25% of its population by 2005, according to UNU’s Ghana-based Institure for Natural Resources in Africa. • Globally, desertification claims Nebraska-sized area of productive capacity each year.

5. Overgrazing and to a lesser extent drought in the 1930s transformed parts of the Great Plains in the United States into the “Dust Bowl”. During that time, a considerable fraction of the plains population abandoned their homes to escape the unproductive lands. Improved agricultural and water management have prevented a disaster of the earlier magnitude from recurring. Desertification is widespread in many areas of the People’s Republic of China. The population of rural areas have increased since 1949 for economical reasons as more people have settled there. While there has been an increase in livestock, the land available for grazing has decreased. Also the importing of European cattle such as Friesian and Simmental, which have higher food intakes, has made things worse. Another example of desertification occurring is in the Sahel. The chief cause of desertification in the Sahel is slash-and-burn farming practiced by an expanding human population. The Sahara is expanding south at a rate of up to 48 kilometers per year.

6. Human overpopulation is leading to destruction is leading to destruction of tropical wet forests and tropical dry forests, due to widening practices of slash-and-burn and other methods of subsistence farming necessitated by famines in lesser developed countries. A sequel to the deforestation is typically large scale erosion, loss of soil nutrients and sometimes total deforestation. Examples of this extreme outcome can be seen on Madagascar’s central highland plateau, where about seven percent of the country’s total land mass has become barren, sterile land. Overgrazing has made the Rio Peurco Basin of central New Mexico one of the most eroded river basins of the western United States and has increased the high sediment content of the river. Overgrazing is also contributing to desertification in some parts of Chile, Ethiopia, Morocco and other countries. Overgrazing is also an issue with some regions of South Africa such as the Waterberg Massif, although restoration of native habitat and game has been pursued vigorously since +- 1980. Ghana and Nigeria currently experience desertification; in the latter, desertification overtakes about 1,355 square miles (3,510km2) of land per year. The Central Asian countries, Kazakhstan, Kyrgyzstan, Mongolia, Tajikistan, Turkmenistan, and Uzbekistan, are also affected. More than 80% of Afghanistan’s and Pakistan’s land could be subject to soil erosion and desertification. In Kazakhstan, nearly half of the cropland has been abandoned since 1980. In 1980. In Iran, sand storms were said to have buried 124 villages in Sistan and Baluchestan Province in 2002, and they had to be abandoned. In Latin America, Mexico and Brazil are affected by desertification.

8. MITIGATION CONCEPTS Sand fences can be used to control drifting of soil and sand and soil erosion.A recent development is the Seawater Greenhouse and Seawater Forest. This proposal is to construct these devices on coastal deserts in order to create freshwater and grow food.A similar approach is the Desert Rose concept.These approaches are of widespread applicability, since the relative costs of pumping large quantities of seawater inland are low.Another related concept is ADRECS – a system for rapidly delivering soil stabilisation and re forestation techniques coupled with renewable energy generation.

9. DESERTIFICATION AND POVERTY • Numerous authors underline the strong link between desertification and poverty. The proportion of poor people among population is noticeably higher in dryland zones, especially among rural populations. This solution increases yet further as a function of land degradation because of the reduction in productivity, the precariousness of living conditions and difficulty of access to resources and opportunities. • A downward spiral is created in many undeveloped countries by overgrazing, land exhaustion in many undeveloped countries by the marginally productive world regions due to overpopulation pressures to exploit marginal drylands for farming. Decision-makers are understandably averse to invest in arid zones with low potential. This absence of investment contributes to the marginalization of these zones. When unfavourable agro-climatic conditions are combined with an absence of infrastructure and access to markets, as well as poorly-adapted production techniques and an underfield and undereducated population, most such zones are excluded from development.

10. SOURCES http://www.greenfacts.org/en/desertification/index.htm http://en.wikipedia.org/wiki/Desertification http://en.wikipedia.org/wiki/Dust_Bowl