Desertification: the scourge of Africa
WITHIN THE LAST DECADE or so, 25 countries in Africa have faced drastic food shortages as a result of the extended drought.
The reduced capacity for food production has brought a population of over 200 million people to the verge of calamity. Some have died of starvation, and among the survivors, especially the children and young people, many will suffer impaired health for the rest of their lives.
The international community brought in emergency aid, both in the form of food supplies and of technical assistance in rehabilitating drought victims. However, the drought hazard in Africa can be expected to continue, recurring at unpredictable intervals. It cannot be overcome by one-time massive injections of emergency aid. A long-range strategy must be developed which is capable of being realized under the given constraints of these impoverished regions through sustainable development of their fragile environment.
The droughts and famines that have swept over Africa in the past and which are likely to strike again are not sudden natural disasters. Nor are they simply caused by lack of rainfall. They are the end-results of a long deterioration in the ability of Africa to feed itself, a decline caused largely by mistakes and mismanagement both inside and outside the continent.
As Lloyd Timberlake, author of Africa in Crisis, puts it, Africa has "taken too much from its land. It has overdrawn its environmental accounts," and the result for much of the continent has been "environmental bankruptcy."
What Timberlake calls "environmental bankruptcy" has come about as a result of an intricate process of land degradation whereby the biological potential of the continent and its ability to support populations is severely diminished. Desertification is the term that has recently been given to this process. Its main causes are drought, desiccation and human activities. Drought is protracted rainfall failure. Its duration is usually short-term, one to two years. In ecological terms, it is a dry period from which an ecosystem often recovers rapidly after the rains return. Desiccation is a process of aridification resulting from a dry period lasting in the order of decades. Human activities include overcultivation, overgrazing, deforestation, poor irrigation practices and any other inappropriate land use and human management of ecosystems.
Nowhere in Africa are the effects of desertification felt as in the arid, semi-arid and sub-humid lands. These drylands lie mostly along the fringes of the two great deserts in the continent the Sahara and the Kalahari where the average annual precipitation is between 100mm and 600mm and where the ecology is largely based on crop and livestock farming activities.
Drylands in Africa, including the hyper-arid deserts, comprise 1,959 million hectares (ha) or 65% of the continent and about one-third of the world's drylands. One-third of this area is hyper-arid deserts (672 million ha). These are uninhabited, except in oases. The remaining two-thirds, or 1,287 million ha, comprise the arid and semi-arid lands (ASAL). Nearly 400 million people (two-thirds of all Africans) live in the latter.
It has been estimated that 34% of the surface area of Africa is under the threat of desertification. This is equivalent to four-fifths of the ASAL areas of Africa. Desertification affects three principal areas of the continent, namely, Mediterranean Africa, the Sudano-Sahelian region and Africa south of the Sudano-Sahelian.
In Sub-Saharan Africa, and in particular the ASAL areas, one of the foremost causes of desertification is drought. Virtually every year there is drought in some part of the ASAL or another. Major droughts, however, regularly affect large portions of these dry lands. Examples include the droughts of 1968-73, 1982-85 and 1990-92. During each of these droughts many countries in the ASAL experienced substantial food shortages. With each drought cycle dryland degradation increases. The Sudano-Sahel region has experienced unpredictable and severe droughts, the most recent of which has lasted almost 20 years. This is desiccation.
The second and perhaps the most important cause of environmental degradation in the ASAL is the rapidly increasing human and animal population pressure, leading to overexploitation of and intensified stresses on the natural resources. The human population in Africa's ASAL has doubled in the past three decades to nearly 400 million and continues to expand at a rate of three percent a year. This means that the ASAL's natural resources must feed an additional 12 million people every year, good weather or bad.
This problem of rapidly increasing population pressures on the fragile and vulnerable soils of Africa's dryland regions translates into overexploitation of water, land, forest and pasture resources through overcultivation, overgrazing, deforestation and poor irrigation practices. The resulting erosion and degradation of productive lands has led to food insecurity.
The extent of desertification as revealed by UNEP's 1991 assessment is alarming. About 73% of the total agriculturally-used dryland in Africa is affected to some degree by various forms of land degradation. About 74% of the continent's rangelands, 61% of the rainfed croplands and 18% of its irrigated lands are already affected by desertification at a moderate or higher degree. This land has lost 25% or more of its fertility and the process is still going on.
The key problem is soil erosion. Soil, the thin layer of top-soil on which our survival depends, is a non-renewable resource. For nature to form a layer of top-soil thick enough to support plant life takes thousands of years. Through human misuse, the layer can be destroyed in a few decades, or in a few years. Once eroded, its loss is permanent. That is desertification.
The continent's precious top-soil is being lost at incredible rates. Experts define that any erosion rate above 50 tons per square kilometre, 0.5 tons per ha, is `unusual'. Others say that 10 tons per ha is barely `acceptable'. In some parts of the Sudano-Sahelian region, soil erosion figures as high as 450 tons per ha per year are not unusual.
In Ethiopia, an estimated one billion tons of top-soil is lost each year, as compared to four billion tons in the United States which has several times Ethiopia's area of cropland. Observers describe hillside fields that have been eroded down to bedrock in the course of a decade or two.
Throughout most of Sub-Saharan Africa the situation is worsening rapidly. Deforestation is accelerating and continued large increases in rural and urban populations are likely to further exacerbate this process over the next few decades.
The exploitation of woodland resources around towns is leading to deforestation, increased soil erosion and sand dune encroachment. The rapidly growing demand for charcoal among urban populations is leading to severe desertification within a 40-50km radius of many large urban centres in eastern Africa and the Sahel. According to some reports, rising charcoal consumption in the Sudanese capital, Khartoum, has caused the area of charcoal production to shift to the south by an average of 15-20km a year. The charcoal supplies for Khartoum now come from as far as 400km away.
The incidence of deforestation resulting from fuelwood requirements and in association with subsistence and commercial farming is spreading throughout the Sudano-Sahel region. The impact of drought, together with steadily increasing population pressure on arable land, has led subsistence farmers to move out of marginal or depleted lands to extend cultivation into forested areas or fragile river basins and mountain zones. The encroachment of cultivation on these vulnerable lands has led to loss of biodiversity and accelerated soil erosion, making the people even more vulnerable to future droughts.
If we look at the countries of eastern and southern Africa, we find basically similar problems: fragile soils being degraded through improper cultivation practices, fuelwood cutting leading to deforestation, and overgrazing destroying the ground cover over large areas.
All of these factors combine to leave the land more vulnerable to drought and soil erosion. As a result, vast tracts of land in Africa's ASAL are being transformed into `dust bowls', losing their productivity and impoverishing their populations.
The consequences of land degradation are already being felt in much of Africa. Accelerating desertification is largely responsible for the fact that many countries in Africa south of the Sahara are losing the capacity to feed themselves. Compounded by the rapid population growth at the rate of three per cent, this is shown by the fact that between 1970 and 1980 per capita food production in Sub-Saharan Africa dropped by 11 per cent. And that was before these countries felt the full impact of the last drought. In effect, desertification is rapidly destroying the natural resource base on which the future of our nations so much depends.
Africa provides increasing evidence for linking the impact of climate and climate change and variability with the incidence of environmental degradation in arid and semi-arid lands.
The recent assessment of desertification and drought by the United Nations Statistical Office (UNSO) shows that the main threats to sustainability in the Sudano-Sahel zone are low and erratic rainfall, coupled with soil erosion by wind, water and the drying up of surface water resources and the depletion of ancient groundwater and salinization of soils. As a result of the extended drought which peaked during the early 1970s and mid 1980s, Lake Chad at its worst point contracted to one-third of its normal size. Several other lakes and rivers throughout the Sudano-Sahel in western and eastern Africa have fallen to record low levels and the land has been severely damaged by erosion. The UNSO report shows that the effects of desiccation on rangeland have been much more serious than those of droughts. Many pastoral communities in the Sudano-Sahel region "have simply ceased to exist as such after the desiccation of the last 20 years."
Africa also provides evidence of the effect of progressive land degradation on local climate, and some recent studies in Botswana shed light on this. At Mahalapye in the east and Ghanzi in the west, rises in mean maximum temperature of the order respectively of 0.3°C and 0.2°C for the initial months preceding the rainy season (August-October) have been observed for the period 1921-1946, and rises of 0.7°Celsius and 1.0°C for the period 1951-70. It is claimed that this sharp rise in temperature coincided with a great increase in grazing pressure. At sites in the Western Kalahari, daily maximum and minimum surface temperatures over bare ground are reported to increase significantly with height above ground level. Cooler temperatures over bare ground were thought to be due to the higher albedo or reflectivity over bare sandy soil rather than over vegetated surface. This thermal depression effect results in a decreased lifting of air necessary for precipitation mechanisms to operate, and may result in local climatic deterioration. Desertification in Africa's ASAL, thus, poses a real danger of a heat inversion developing over several parts of the continent which would lead to a decrease in rainfall.
Finally, in many African countries desertification is creating `environmental refugees'. In increasing numbers, people are forced to abandon their land because it can no longer sustain them and migrate to other regions or to urban slums. This problem of environmental refugees and the widespread socio-political upheavals in many African countries today are a foretaste of what we can expect if we do not halt desertification.
For some time now, governments and non-governmental organizations in the region have been taking measures at local and national levels to combat desertification. The UN Plan of Action to Combat Desertification (PACD) has provided guidelines for many national plans of action. But so far, the efforts of these countries have met with limited success. This limited success in combating desertification has been attributed to lack of funds on the one hand and an inequitable international economic order on the other. While both are key factors, there are other important issues.
Other factors accounting for the limited success are land tenure and property rights, wars and civil strife, and misdirected research priorities.
In its evaluation of the PACD, UNEP found that the main cause of the failure to implement PACD was the failure of African governments and the donor community to make desertification a priority issue. Because of scarce financial resources, and the competing (and often conflicting) demands on them, African countries are unable at present to assign sufficiently high priority to desertification prevention or control, and have only to a limited degree included some measures in their national development plans.
Lack of financial resources from external donors have also created constraints. Like African governments, donors prefer projects that will yield quick visible results that can easily be economically quantified. UNEP also found that several countries suffering from desertification in Africa lack adequate national legislation to stop the human-induced causes of the problem.
Where programmes are developed, they fail because there is little community participation and support. Governments also find it difficult to break through the traditional bureaucratic syndrome of sectoral planning and undertake holistic planning.
Agenda 21, the blueprint for action into the 21st century adopted by the world's governments at the Earth Summit in Rio de Janeiro in June 1992, did map out national strategies for combating desertification:
Will Agenda 21 make governments in Africa and the international community change and take the issue of desertification seriously? It remains to be seen whether Agenda 21 will produce the level of action needed to address dryland problems which its predecessor, the PACD, has abysmally failed to produce and address in Africa.
Professor M B K Darkoh, Geography Department, Kenyatta University, PO Box 43844, Nairobi, Kenya.
Published Issue 8, April 1993