How will different future development paths influence desertification? Population growth and increased food demand are expected to drive the expansion and intensification of land cultivation in drylands. If no countermeasures are taken, desertification in drylands will threaten future improvements in human well-being and possibly reverse gains in some regions. The different scenarios are based on either increased globalization or increased regionalizationeach combined with either a reactive or proactive way of addressing environmental issues.
See Article History Alternative Title: Declines in productivity may be the result of climate changedeforestationovergrazing, povertypolitical instability, unsustainable irrigation practices, or combinations of these factors.
The concept does not refer to the physical expansion of existing deserts but rather to the various processes that threaten all dryland ecosystemsincluding deserts as well as grasslands and scrublands.
The United Nations Environment Programme UNEP notes that desertification has affected 36 million square km 14 million square miles of land and is a major international concern.
A report by the United Nations University maintains that the lives of to million people are affected by desertification. The report also notes that this phenomenon may cause the displacement of about 50 million people bymaking it one of the most severe environmental challenges facing humanity.
Africa is the continent most affected by desertification, and one of the most obvious natural borders on the landmass is the southern edge of the Sahara desert. The countries that lie on the edge of the Sahara are among the poorest in the world, and they are subject to periodic droughts that devastate their peoples.
African drylands which include the Sahara, the Kalahariand the grasslands of East Africa span 20 million square km about 7.
Some one-fifth of the irrigated cropland, three-fifths of the rain-fed cropland, and three-fourths of the rangeland have been at least moderately harmed by desertification. Causes and consequences of desertification In general, desertification is caused by variations in climate and by unsustainable land-management practices in dryland environments.
By their very nature, arid and semiarid ecosystems are characterized by sparse or variable rainfall. Thus, climatic changes such as those that result in extended droughts can rapidly reduce the biological productivity of those ecosystems.
Such changes may be temporary, lasting only a season, or they may persist over many years and decades.
On the other hand, plants and animals are quick to take advantage of wetter periods, and productivity can rapidly increase during these times. A woman in Nigeria pouring grains of millet into a bowl in the village of Sadongori Kolita, near Maradi.
Low rainfall and locusts caused a food crisis during the summer of The conference explored the causes and contributing factors and also possible local and regional solutions to the phenomenon.
In addition, the delegates considered the varied consequences of desertification, such as crop failures or decreased yields in rain-fed farmland, the loss of perennial plant cover and thus loss of forage for livestockreduced woody biomass and thus scarcity of fuelwood and building materials, a decrease in potable water stocks from reductions in surface water and groundwater flow, increased sand dune intrusion onto croplands and settlements, increased flooding due to rising sedimentation in rivers and lakesand amplified air and water pollution from dust and sedimentation.
Four areas affected by desertification To better understand how climatic changes and human activities contribute to the process of desertification, the consequences listed above can be grouped into four broad areas: Irrigated croplands, whose soils are often degraded by the accumulation of salts.
Rain -fed croplands, which experience unreliable rainfall and wind-driven soil erosion. Grazing lands, which are harmed by overgrazing, soil compactionand erosion. Dry woodlands, which are plagued by the overconsumption of fuelwood.
Over 60 percent of these irrigated areas occur in drylands. Certainly, some dryland areas have been irrigated for millennia, but other areas are more fragile.
Of the irrigated dryland, 30 percent an area roughly the size of Japan is moderately to severely degraded, and this percentage is increasing. There is an important difference between rainwater and the water used for dryland irrigation. Rainwater results from the condensation of water evaporated by sunlight.
Essentially, rainwater is distilled seawater or lake water. In contrast, water used for irrigation is the result of runoff from precipitation.
Runoff percolates through the soil, dissolving and collecting much of the salts it encounters, before finding its way into rivers or aquifers.
When used to irrigate crops, runoff evaporates and leaves behind much of the salts that it collected. Irrigated crops need an average of 80 cm about 30 inches of water annually.
These salts can build up in the soil unless additional water is used to flush them out. This process can rapidly transform productive land into relatively barren salt flats scattered with halophytes plants adapted to high levels of salt in the soil.
Solonchak soil profile from China, showing a surface horizon with high salt accumulation. In Asia, Iraq has lost over 70 percent of its irrigated land to salt accumulation.
In Russia, much of the irrigated land located where the Volga River runs into the Caspian Sea may last only until the middle of the 21st century before the buildup of salts makes it virtually unusable. Such losses are not restricted to developing countries.What are the major causes of desertification?
Desertification is caused by a combination of social, political, economic, and natural factors which vary from region to region. Water erosion and reduced soil conservation in semi-arid Burkina Faso negatively affects ecosystem services. Desertification has played a major part in much of recent human history (last 10, or so years).
It’s contributed to the collapse of many major civilizations and empires — from Carthage, to the Harappan Civilization, to Ancient Greece, to the Roman Empire, to Ancient China, etc.
only is desertification harmful to the earth and its inhabitants, but it is also expensive – each year, the world loses US$42 billion to desertification and its effects. The causes of desertification are both natural and man-made. There is no consensus among researchers as to the specific causes, extent, or degree of desertification.
Contrary to many popular reports, desertification is actually a subtle and complex process of deterioration that may often be reversible. Studies using Landsat data help demonstrate the impact of people and animals on the Earth. However. Causes of Drought Rainfall or Precipitation Deficiency Droughts take place whenever there is prolonged periods of rainfall deficiency for a season or more and usually .
Causes and effects of desertification: Desertification is defined as a process of land degradation in arid, semi-arid and sub-humid areas due to various factors including climatic variations and human activities. Overgrazing is the major cause of desertification worldwide.
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