7.3 - Causes of Desertification & Deforestation
Natural causes of desertification
Desertification is the process by which fertile land degrades into desert, often due to a combination of environmental factors. Natural causes play a significant role in this transformation, primarily through changes in climate and soil conditions that reduce the land's ability to support vegetation.
Key natural factors leading to desertification
- Changing rainfall patterns - In recent times, rainfall has become increasingly unpredictable, with some regions experiencing extended drought periods lasting multiple years. This lack of consistent water causes vegetation to wither, exposing bare soil.
- Soil erosion - The loss of topsoil due to wind or water reduces the ground's capacity to anchor plants, further accelerating degradation.
- Intensity of rainfall - When rain does occur, it often comes in short, heavy bursts. Such intense downpours prevent the soil from effectively absorbing and retaining water, leading to reduced water resources.
- Climate change impacts:
- Rising global temperatures exacerbate dryness, lowering rainfall levels and increasing evaporation.
- This results in bare, dry soil and creates a cycle where increased overland water flow washes away soil or lowers the water table.
- The land becomes drier and more prone to becoming a dust bowl.
- Reduced plant growth - With limited water and eroded soil, fewer plants can grow, making farming nearly impossible and pushing the land towards full desertification.
Human causes of desertification
Beyond natural factors, human activities significantly contribute to desertification, often intensifying the pressure on already fragile environments. These actions are driven by the need for resources and space, particularly in developing regions.
Main human activities contributing to desertification
- Population growth - A rapidly increasing population demands more food production, placing greater strain on the land to cultivate crops and sustain livestock.
- Migration pressures - As desertification affects certain areas, communities move to new locations in search of water and arable land, increasing environmental stress in those new regions.
- Overgrazing - Excessive numbers of livestock, such as goats and cattle, graze on vegetation, particularly around water sources in desert margins, stripping the land of plant cover and leaving soil vulnerable.
- Over-cultivation - Continuous farming on marginal lands depletes soil nutrients, rendering it infertile and unable to support crops over time.
- Deforestation - Cutting down trees for fuel, fencing, or building materials removes root systems that hold soil in place, leading to erosion and further land degradation.
- Conflict and war:
- In regions like sub-Saharan Africa, years of civil unrest have led to the deliberate destruction of crops and livestock.
- This results in famine and widespread loss of life, which worsens environmental damage.
Global impact and vulnerable regions of desertification
Desertification is a global issue affecting millions of people, with certain areas facing greater risks due to their environmental and socio-economic conditions.
Scale and critical areas of desertification
- Global reach - Around one-fifth of the world's population, across over 55 countries, lives with the consequences of desertification, struggling with reduced arable land and water scarcity.
- The Sahel region:
- Located south of the Sahara Desert in Africa, the Sahel stretches across the continent and is one of the most vulnerable areas.
- As part of sub-Saharan Africa, the poorest region globally, it faces severe challenges from both natural drought and human-induced degradation.
- This makes desertification a critical threat to livelihoods.
Reasons for deforestation in tropical rainforests
Deforestation, particularly in tropical rainforests, occurs due to a variety of activities aimed at exploiting forest resources or clearing land for other uses. These actions result in significant loss of biodiversity and environmental damage.
Primary causes of rainforest deforestation
- Commercial logging and timber extraction (accounting for roughly a quarter globally):
- Selective logging targets valuable trees, but their felling damages surrounding vegetation.
- Clear-felling, where entire areas are cut for pulp, causes even greater destruction.
- Agriculture (responsible for over 30% globally):
- Vast forest areas are cleared for plantations growing single crops like rubber or coffee.
- Land is converted to grassland for cattle grazing, often for a few years before new areas are cleared.
- Mining activities - Large tracts of forest are removed for open-cast mining of minerals such as iron, gold, and copper, disrupting ecosystems.
- Hydroelectric power (HEP) projects - Damming rivers for energy production floods extensive forest areas, submerging ecosystems under water.
- Land for subsistence farmers - Forests are cleared to provide land for farmers to grow food and use timber as fuel, also reducing overcrowding in other regions.
- Road construction:
- Roads are built through rainforests to transport minerals, timber, cattle, and crops.
- This facilitates further settlement and farming by new arrivals, which leads to additional clearance.
Economic and social drivers behind deforestation
Governments and communities in developing countries often support or encourage deforestation due to pressing economic needs and population pressures. These drivers reflect a complex balance between immediate benefits and long-term environmental costs.
Factors encouraging deforestation
- Revenue generation - Selling timber, minerals, and medicinal resources derived from forests provides income to pay off national debts and fund development projects in countries like Brazil and Malaysia.
- Population demands - Rapidly growing populations require more land for housing and food production, pushing governments to clear forests to meet these needs.
- Unregulated practices - In many cases, logging and land clearance occur illegally or without proper oversight, exacerbating the rate of deforestation as control measures are absent or ineffective.
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