The causes of desertificationDesertification is the degradation of drylands. It involves the loss of biological

The causes of desertification

Desertification is the degradation of drylands. It involves the loss of biological or economic productivity and complexity in croplands, pastures, and woodlands. It is due mainly to climate variability and unsustainable human activities. The most commonly cited forms of unsustainable land use are overcultivation, overgrazing, deforestation, and poor irrigation practices. Seventy percent of the world’s drylands (excluding hyper-arid deserts), or some 3,600 million hectares, are degraded. While drought is often associated with land degradation, it is a natural phenomenon that occurs when rainfall is significantly below normal recorded levels for a long time.

Drylands respond quickly to climatic fluctuations. By definition, drylands have limited freshwater supplies. Precipitation can vary greatly during the year. In addition to this seasonal variability, wide fluctuations occur over years and decades, frequently leading to drought. Over the ages, dryland ecology has become attuned to this variability in moisture; plants and animals can respond to it rapidly. For example, satellite imagery has shown that the vegetation boundary south of the Sahara can move by up to 200 km when a wet year is followed by a dry one, and vice versa.

People must also adjust to these natural fluctuations. The biological and economic resources of drylands, notably soil quality, freshwater supplies, vegetation, and crops, are easily damaged. People have learned to protect these resources with age-old strategies such as shifting agriculture and nomadic herding. However, in recent decades these strategies have become less practical due to changing economic and political circumstances, population growth, and a trend towards more settled communities. When land managers cannot or do not respond flexibly to climate variations, desertification is the result.

The relatively low priority given to environmental protection often leads to poor land management decisions. The overuse of land may result from specific economic conditions or from inappropriate land laws or customs. In many cases, unregulated access to land resources may lead some individuals to maximize their own gains by overexploiting the land at the expense of the community as a whole. Poor people, particularly poor women, often lack access to the best land, depending instead on the most fragile areas and resources. Their poverty may give them little alternative but to extract what they can from the scarce resources available to them, even though this degrades the land.

International economic forces can encourage people to overexploit their land. International trade patterns can lead to the short-term exploitation of local resources for export, leaving little profit at the community level for managing or restoring the land. Similarly, the development of an economy based on cash crops, or the imposition of taxes, can distort local markets and promote overexploitation of the land.

Ignorance, errors, and natural and man-made disasters can also contribute to land degradation. Ignorance of the natural environment played an important role in the US during the infamous Dust Bowl of the 1930s; among other errors, during a time of drought Midwestern farmers used ploughs better suited for the more temperate latitudes of Western Europe. In recent decades, similar mistakes in the choice of policies or technologies have led to land degradation in many countries, both developed and developing. Disasters such as wars and national emergencies also destroy productive land by displacing its managers or causing heavy concentrations of migrants to overburden an area. Natural disasters such as floods and droughts can have a similar effect.

What role do increasing populations and population densities play? It is tempting to conclude that an expanding human population is the ultimate driving force behind desertification. More people in an area inevitably exert a greater pressure on that area’s resources; sometimes this pressure is indirect, as when growing urban populations place demands on food production in uncrowded rural areas. But the causes of desertification are complex, and the relationship between two variables such as population and desertification is not clear-cut. For example, a decline in population can result in desertification since there may no longer be enough people to manage the land adequately. Many hillside terraces in Yemen have fallen into disrepair with the exodus of labour to neighbouring oil-rich countries. Examples can also be cited of areas that support large concentrations of people without much degradation, such as around the city of Kano in Nigeria.

The consequences of desertification

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.

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The consequences of desertification

Soil becomes less productive. 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. When soil is trampled and compacted by cattle, it can lose 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. Loose soil can sandblast plants, bury them, or leave their roots dangerously exposed. When pastures are overgrazed by too many animals, or by inappropriate types, edible plant species may 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, sedimentation in rivers and lakes, and siltation of reservoirs and navigation channels. It can also cause dust storms and air pollution, resulting in damaged machinery, reduced visibility, unwanted sediment deposits, and mental stress. Wind-blown dust can also worsen health problems, including eye infections, respiratory illnesses, and allergies. Dramatic increases in the frequency of dust storms were recorded during the Dust Bowl years in the US, in the Virgin Lands scheme area in the former USSR in the 1950s, and in the African Sahel during the 1970s and 1980s.

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. Malnutrition, starvation, and ultimately famine may result. The relationship between soil degradation and crop yields, however, is seldom straightforward. 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 typically occurs in areas that also suffer from poverty, civil unrest, or war. 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.

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 further undermine social stability.

Desertification is a huge drain on economic resources. 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). At the global level, it is estimated that the annual income foregone in the areas immediately affected by desertification amounts to approximately US$ 42 billion each year. 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.

Action programmes for combating desertification

The Convention to Combat Desertification is being implemented through national action programmes (NAP). Developed country Parties and affected country Parties are expected to consult on their respective roles in supporting these programmes, which can result in a more holistic, integrated and participatory management of natural resources in drylands ecosystems. Once significant effort has been made to design a framework programme, international solidarity might facilitate the launching of specific projects and activities under the agreed policies, in an effective manner and without creating excessive transactional burden. Because programmes need to be adapted to particular regional circumstances, most of the specific requirements are described in the five regional implementation annexes for Africa, Asia, Latin America and the Caribbean, the northern Mediterranean and Central and Eastern Europe. As at August 2005, 77 National Action Programmes (NAPs) had been prepared and adopted. These instruments are considered to be core references for an ongoing process of planning for poverty reduction and the sustainable development of drylands.

Efforts to combat desertification should be fully integrated into other development programme frameworks. Reversing land degradation and alleviating poverty go hand in hand. Both involve improving food security, educating and training people, strengthening the capacity of local communities, and mobilizing non-governmental organizations. Similarly, because desertification affects and is affected by environmental concerns such as loss of biological diversity and climate change, NAPs need to have a great potential to promote synergies with other programmes dealing with such issues. However, improved data at the country level and stronger recognition of the NAPs have yet to manifest this potential fully through concrete initiatives. Parties have suggested the holding of national workshops involving the three conventions‘ focal points in order to facilitate further the implementation of joint work programmes.

Programmes outline long-term strategies and are formulated with the active participation of local communities. These are essential for providing ownership and continuity for long-term programming. The participatory process enables governments to coordinate and administer their resources more effectively while addressing the underlying socio-economic causes of desertification. These approaches pay particular attention to preventive measures and encourage a sense of commitment to sustainable practices by the very people who most depend upon the land. The programmes should be sufficiently flexible to accommodate new initiatives and local adaptations as circumstances change. In many instances, the strengthening of the capacities of key actors at the local level has proved successful in identifying and addressing challenges linked to decision making for natural resources management. The lack of a strong civil society presence in other affected states, however, continues to be a drawback in ensuring people‘s participation in the mainstream policy formulation and implementation process.

NAPs also specify the practical steps and measures to be taken as well as the commitments made by national governments to provide an “enabling environment”. Specific measures to improve the economic environment could include creating financial instruments suited to local needs or the introduction of drought-resistant crops. Other measures could include promoting research activities, drought contingency plans, and improved early warning systems. National governments, for their part, can make commitments to remove obstacles and provide support by enacting new laws or strengthening existing legislation and adopting policies that encourage sustainable development, such as the replacement of fuelwood by other energy sources. Part of the national budget must be clearly earmarked for efforts to combat desertification and drought according to national conditions and capabilities, but the NAPs are also expected to mobilize substantial financial resources from external sources. Lack of predictable programme resources and funding has slowed and impeded the implementation of NAPs. As Parties are now moving from the phase of programme preparation to that of implementation, the establishment of a country-driven mechanism to mobilize international support to the NAP in affected country Parties is urgently called for.

Subregional and regional action programmes (SRAPs and RAPs)can help to harmonize and strengthen national programmes. These are designed through consultations among the affected countries of each region (such as Africa) and sub-region (such as West Africa). In addition to boosting the efficiency of national programmes, SRAPs and RAPs can promote joint programmes for the sustainable management of shared rivers and other cross-boundary ecosystems. The thematic programme networks which often constitute the main elements of RAPs generate spin-off effects on activities taking place at the national level, such as water management, agroforestry and monitoring, and forge each country‘s scientific and technical capacities. They may help in disseminating the knowledge of appropriate technologies and good practices. As at August 2005, 9 subregional and 3 regional action programmes had been launched.

A comprehensive assessment conducted by the Parties in 2000 and 2001 emphasized the possibility of duplicating best practices and successes. Successful programme activities and outcomes identified were, inter alia, contribution to a more integrated approach linking national development frameworks and drylands conservation, the strengthening of relationships between governments and local communities, especially in larger countries, the decentralized involvement of stakeholders and natural resources end users in the development process for a variety of programmes beyond the Convention, aided by consultative mechanisms at the regional and local levels, the establishment of national information systems on desertification to enhance information flow between all parties involved, and private enterpreunership, social mobilization and the application of appropriate technologies such as drip irrigation, soil conditioning, hydroponic crop production and ecotourism projects.

The Parties identified the integration of sustainable development policies into economic policies as a challenge to be overcome. They highlighted the urgent need for of inter-ministerial cooperation and for the mainstreaming of action programmes into development strategies in order to address the problem in a comprehensive manner and to avoid duplication. Given that the NAPs cut across many development sectors such as agriculture, forestry and water management, the NAPs have, at times, encouraged inter-ministerial cooperation and focused attention on inappropriate land tenure or certain trade practices not conducive to sustainable land use. Furthermore, Parties called for the insertion of Convention-related measures into bilateral and multilateral negotiations.

Desertification is the process which turns productive into non- productive desert as a result of poor land-management. Desertification occurs mainly in semi-arid areas (average annual rainfall less than 600 mm) bordering on deserts. In the Sahel, (the semi-arid area south of the Sahara Desert), for example, the desert moved 100 km southwards between 1950 and 1975.

WHAT CAUSES DESERTIFICATION?
* Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions. Early human pastoralists living in semi-arid areas copied this natural system. They moved their small groups of domestic animals in response to food and water availability. Such regular stock movement prevented overgrazing of the fragile plant cover.

In modern times, the use of fences has prevented domestic and wild animals from moving in response to food availability, and overgrazing has often resulted. However, when used correctly, fencing is a valuable tool of good veld management.

The use of boreholes and windmills also allows livestock to stay all-year round in areas formerly grazed only during the rains when seasonal pans held water. Where not correctly planned and managed, provision of drinking water has contributed to the massive advance of deserts in recent years as animals gather around waterholes and overgraze the area.

* Cultivation of marginal lands, i.e lands on which there is a high risk of crop failure and a very low economic return, for example, some parts of South Africa where maize is grown.

* Destruction of vegetation in arid regions, often for fuelwood.

* Poor grazing management after accidental burning of semi-arid vegetation.

* Incorrect irrigation practices in arid areas can cause salinization, (the build up of salts in the soil) which can prevent plant growth.

When the practices described above coincide with drought, the rate of desertification increases dramatically.

Increasing human population and poverty contribute to desertification as poor people may be forced to overuse their environment in the short term, without the ability to plan for the long term effects of their actions. Where livestock has a social importance beyond food, people might be reluctant to reduce their stock numbers.

WHAT ARE THE EFFECTS OF DESERTIFICATION?
Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and people. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa losing approximately 300-400 million tonnes of topsoil every year. As vegetation cover and soil layer are reduced, rain drop impact and run-off increases.

Water is lost off the land instead of soaking into the soil to provide moisture for plants. Even long-lived plants that would normally survive droughts die. A reduction in plant cover also results in a reduction in the quantity of humus and plant nutrients in the soil, and plant production drops further. As protective plant cover disappears, floods become more frequent and more severe. Desertification is self-reinforcing, i.e. once the process has started, conditions are set for continual deterioration.

HOW CAN DESERTIFICATION BE HALTED?
To halt desertification the number of animals on the land must be reduced, allowing plants to regrow. Soil conditions must be made favourable for plant growth by, for example, mulching. Mulch (a layer of straw, leaves or sawdust covering the soil) reduces evaporation, suppresses weed growth, enriches soil as it rots, and prevents runoff and hence erosion. Reseeding may be necessary in badly degraded areas. Mulching and reseeding are expensive practices.

However, the only realistic large-scale approach is to prevent desertification through good land management in semi-arid areas.