by Henrylito D. Tacio
“Across the planet, poverty, unsustainable land management and climate change are turning drylands into deserts, and desertification in turn exacerbates and leads to poverty,” commented former United Nations Secretary-General Kofi Annan during the World Environment Day two years ago.
Across Asia, desertification is evident in many different forms. Out of a total land area of 4.3 billion hectares, Asia contains some 1.7 billion hectares of arid, semi-arid, and dry sub-humid land reaching from the Mediterranean coast to the shores of the Pacific. “Vast expanse of these areas is affected by desertification,” deplores the Manila-based Asian Development Bank.
Desertification became well known in the 1930’s, when parts of the Great Plains in the United States turned into the “Dust Bowl” as a result of drought and poor practices in farming, although the term itself was not used until almost 1950. During the dust bowl period, millions of people were forced to abandon their farms and livelihoods.
“One of the most serious global environmental problems” is how the Kenya-based United Nations Environment Program (UNEP) calls desertification. “Desertification is destroying the food producing capacity of vast tracts of dryland in every continent of the world,” it explains. “Many millions of people living in 110 countries would suffer from its effects.”
Desertification is defined by the UN Convention to Combat Desertification (UNCCD) as “land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities.” Land degradation in drylands is defined as the reduction or loss of the biological or economic productivity of drylands.
Drylands, which are characterized by “low rainfall” and “high rates of evaporation,” occupy 41 percent of the world’s land area and are home to more than two billion people. “Half of all people living in poverty live in drylands,” UNEP states. “They depend heavily on environmental services for their basic needs.”
Between 10 and 20 percent of drylands are already degraded, according to the UNEP estimates. “The problem is acute in developing countries, where dryland degradation is a serious obstacle to eradicating extreme poverty and hunger, and is jeopardizing efforts to ensure environmental sustainability,” Annan commented. In Asia, about 1 million hectares are subject to desertification.
The total land area affected by desertification is estimated as between 6 and 12 million square kilometers. That is almost the size of Brazil, Canada and China combined – which is about between 8 and 10 million square kilometers.
Drylands contain 43 percent of the world’s cultivated land. “Land degradation causes an estimated loss of US$42 billion a year from agricultural production,” UNEP said in a statement. Nearly one-third of the world’s cropland has been abandoned in the past 40 years because erosion has made it unproductive. “Each year an additional 20 million hectares of agricultural land becomes too degraded for crop production or is lost to urban sprawl,” Annan added.
To some degree, desertification is found on 30 percent of irrigated lands, 47 percent of rain-fed agricultural lands, and 73 percent of rangelands. “Annually, an estimated 1.5 to 2.5 million hectares of irrigated land, 3.5 to 4 million hectares of rain-fed agricultural land, and about 35 million hectares of rangeland lose all or part of their productivity due to land degradation,” UNEP said.
A paper circulated by the London-based Panos Institute identifies four primary causes of desertification: overcultivation, overgrazing, deforestation and poor irrigation practices. Alan Grainer, author of Desertification, says that the four aforementioned causes are influenced by three contributing factors: population changes, climatic changes, and changing social and economic conditions.
Population growth, after all, makes desertification more acute. Climatic changes like drought triggers off a crisis, but does not itself cause desertification, which usually arises as a result of a combination of two or more of the primary causes acting together.
The Panos paper gives some insights:
Overcultivation. This results in part from a growing population requiring more food. Another key factor is demand for foreign exchange, particularly to repay debts, forcing an increase in cash crops. Some authorities claimed that the large-scale development of peanuts in West Africa in the 1960s might have contributed to the Sahel disasters of the 1970s.
“Overcultivation creates a number of conditions which can trigger desertification: declining soil fertility and declining crop yield; crusting of exposed topsoil by rain and sun; increase surface runoff, erosion of soil by water and gullying; blowing away of exposed topsoil by wind; encroachment of sand dunes on arable land; and destruction of crops by dust-bearing winds,” the Panos paper explains.
Overgrazing. The 1968-73 Sahel disaster has also been traced to overgrazing. It is the direct result of the growing human population; there are more mouths to feed and more land is devoted to food crops. Thus, the size of herds increases while pasture area decreases.
Overgrazing causes desertification through a decline in the annual production of pasture vegetation and a decrease in palatable grass species, particularly perennials, which are also good at holding the soil together. Soil compaction, as a result of trampling by stock near waterholes and overgrazing pastures, also triggers desertification.
Irrigation. This is often seen as the answer to food shortages in arid areas, and it has increased the production of cereals and root crops in most parts of the world. But if not properly designed and maintained, irrigation can turn land into desert.
Salinization and alkalinization occur when poor irrigation practices waterlog the soil and allow salts to come to the surface or be carried in by the water when the lack of drainage fails to leach them away. Salinization also occurs around river estuaries when overuse of wells lowers the water table and allows coastal salt and brackish water to infiltrate. A major problem in Bangladesh is caused by a backflow of salt water into river systems, which cover about 38 per cent of the country, where 33 percent of the population lives.
Economic and human impact
Economic, political or social pressures cause practices which lead to land degradation. Most authorities believe that there is a link between underdevelopment and desertification. Non-governmental organizations have argued persuasively that the land use practices, which cause desertification “may be motivated by a whole chain of economic practices which result in poor prices for agricultural and livestock products or political compulsions like debt, which force a country to promote adverse land use practices in order to earn foreign exchange.”
“The consequences of desertification and drought include food insecurity, famine, and poverty,” UNEP pointed out. “The ensuing social, economic, and political tensions can create conflicts, cause more impoverishment and further increase land degradation. Growing desertification worldwide threatens to increase by millions the number of poor forced to see new homes and livelihoods.”
While desertification is hard to reverse, Annan believed it can be prevented. “Protecting and restoring drylands will not relieve the growing burden on the world’s urban areas, it will contribute to a more peaceful and secure world,” the former UN official said. — ###