About this program
Desertification is caused by a combination of factors that change over time and vary by location. These include indirect factors such as population pressure, socioeconomic and policy factors, and international trade as well as direct factors such as land use patterns and practices and climate-related processes.
Desertification is taking place due to indirect factors driving unsustainable use of scarce natural resources by local land users.This situation may be further exacerbated by global climate change.
Desertification is considered to be the result of management approaches adopted by land users, who are unable to respond adequately to indirect factors like population pressure and globalization and who increase the pressure on the land in unsustainable ways. This leads to decreased land productivity and a downward spiral of worsening degradation and poverty. Where conditions permit, dryland populations can avoid degradation by improving their agricultural practices and enhancing pastoral mobility in a sustainable way. On the whole, the interaction between climatic factors and human responses can create a range of different outcomes. To counter the problems effectively, it is important—but difficult—to distinguish between those resulting from the natural conditions of dryland ecosystems and those caused by unsustainable management practices as well as broader economic and policy factors.
Social, Economic and Policy Factors
Policies leading to unsustainable resource use and lack of supportive infrastructure are major contributors to land degradation.
Conversely, this makes public policies and physical infrastructure useful intervention points. Thus agriculture can play either a positive or a negative role, depending on how it is managed. This in turn depends on the socioeconomic resources available, the policies adopted, and the quality of governance. Local institutions, such as community-based land-use decision-making bodies and social networks, can contribute to preventing desertification by allowing land users to manage and use ecosystem services more effectively through enhanced access to land, capital, labor, and technology.
Policies to replace pastoralism with sedentary cultivation in rangelands can contribute to desertification.
Policies and infrastructure that promote farming in rangelands that cannot sustain viable cropping systems contribute to desertification. The majority of dryland areas (65%) are rangelands that are more suited to sustainable pastoralism than crop production. For example, nomadic pastoralism is a rangeland management practice that over the centuries has proved to be sustainable and suited to the ecosystem carrying capacity. Sedentarization of nomads in marginal drylands and other limitations to their transboundary movement lead to desertification because they reduce people’s ability to adjust their economic activities in the face of stresses such as droughts.
Land tenure practices and policies that encourage land users to overexploit land resources can be important contributors to desertification.
When farmers and herders lose control or long-term security over the land they use, the incentives for maintaining environmentally sustainable practices are lost. Problems of water scarcity, groundwater depletion, soil erosion, and salinization have all been recognized as outcomes of deeper policy and institutional failures. Security of tenure does not necessarily imply private property rights; many long-established collective and community-based management practices have operated quite effectively. In successful communal systems, greater transparency and fairness in the allocation of resources to all stakeholders is essential. Private land tenure systems in drylands have been less successful in ensuring that pastoralists have access to various ecosystem services such as provisioning of water and pasture.
Many ongoing processes of globalization amplify or attenuate the driving forces of desertification by removing regional barriers, weakening local connections, and increasing the interdependence among people and between nations.
Globalization can either contribute to or help prevent desertification, but it creates stronger links between local, national, sub-regional, regional, and global factors related to desertification. Studies have shown that trade liberalization, macroeconomic reforms, and a focus on raising production for exports can lead to desertification. In other cases, enlarged markets can also contribute to successful agricultural improvements. For example, a large share of the European Union flower markets is supplied with imports from dryland countries (such as Kenya and Israel).
Global trade regimes and linked government policies influence food production and consumption patterns significantly and affect directly or indirectly the resilience of dryland ecosystems.
Improved access to agricultural inputs (like fertilizers, pesticides, and farm machinery) and export markets typically boosts productivity. Opportunities to gain access to international markets are conditioned by international trade and food safety regulations and by a variety of tariff and nontariff barriers. Selective production and export subsidies, including those embodied in the European Union’s Common Agricultural Policy and the U.S. farm bill, stimulate overproduction of many food crops in those countries. Such distortions to international food markets drive down prices and have often seriously undermined the livelihoods of food producers in many poorer countries. In 2002, industrial countries spent more than $300 billion on their agricultural sectors—about six times the amount allocated to foreign assistance. Conversely, removal of international trade barriers without moderating national policies may also encourage unsustainable agricultural practices.
Land Use Patterns and Practices
Land use changes are responses to changes in the provision of ecosystem services, and they also cause changes in this provision.
Historically, dryland livelihoods have been based on a mixture of hunting, gathering, cropping, and animal husbandry. This mixture varied in composition with time, place, and culture. The harsh and unpredictable climate combined with changing socioeconomic and political factors has forced dryland inhabitants to be flexible in land use. Population pressure, how-ever, has led to a growing tension between two main land uses: pastoral rangeland and cultivated land use. In some areas, this led to intercultural conflicts and desertification as herders and farmers claim access to and use of the same land. In other cases, it led to synergistic interaction and integration between the two land uses, with herders cultivating more land, farmers holding more livestock, and an increased exchange of services between the two groups. The synergistic behavior among pastoralists and farmers is driven by both governmental policies and favorable market opportunities; the two groups cooperate when it is in their own vested interests.
Irrigation has led to increased cultivation and food production in drylands, but in many cases this has been unsustainable without extensive public capital investment.
Large-scale irrigation has also resulted in many environmental problems—such as waterlogging and salinization, water pollution, eutrophication, and unsustainable exploitation of groundwater aquifers—that degrade the drylands’ service provisioning. In such irrigation approaches, rivers are often disconnected from their floodplains and other inland water habitats, and groundwater recharge has been reduced. These human-induced changes have in turn had an impact on the migratory patterns of fish species and the species composition of riparian habitat, opened up paths for exotic species, changed coastal ecosystems, and contributed to an overall loss of freshwater biodiversity and inland fishery resources. On the whole, there is a decline in biodiversity and services provided by inland water systems in drylands, which further exacerbates desertification.
Frequent and intensive fires can be an important contributor to desertification, whereas controlled fires play an important role in the management of dryland pastoral and cropping systems.
In both cases, the use of fire promotes the service of nutrient cycling and makes nutrients stored in the vegetation available for forage and crop production. For example, dryland pastoralists use controlled fire to improve forage quality, and dryland farmers use fire to clear new land for cultivation. Conversely, fires can be an important cause of desertification in some regions when they affect natural vegetation. Excessive intensity and frequency can lead to irreversible changes in ecological processes and, ultimately, to desertification. The consequences of such changes include the loss of soil organic matter, erosion, loss of biodiversity, and habitat changes for many plant and animal species.
Climate change is linked to desertification and the impacts of climate change vary according to region and the management approach adopted.
Climate change is expected to affect the global hydrological cycle and local precipitation trends. The local manifestation of these global climate changes is strongly location-dependent. It is likely that extreme events will further intensify, bringing more floods and more droughts.