Desertification

Question 1

Desertification

Answer 1

• The persistent degradation of drylands ecosystems by human activities and by climate change

Question 2

Changing extent and distribution of hot deserts over the last 10000 years

Answer 2

• Extent of hot deserts has changed with the climatic change in the glacial and interglacial periods of the Pleistocence
• During the last glacial, the extent of arid areas was vast
• 8000 years ago during the ‘holocene climate optimum’ the extent of hot deserts was confined to relatively small areas, mainly in North Africa and the Middle East
• Present day deserts extend over much larger areas

Question 3

Causes of desertification : Climate change

Answer 3

• Less rainfall (total amounts and reliability, increased trough (frequency and intensity) lead to rivers and water holes drying up, leads to vegetation dies and so decrease in protective vegetation cover so desertification
• Higher temperatures increases evaporation, reduced condensation, leads to less rainfall, vegetation dies and so soil is exposed to wind and rain + decrease in protective vegetation cover leading to desertification

Question 4

Causes of desertification : Change in farming

Answer 4

• Increase in livestock numbers
• Causes overgrazing : Soil depleted of nutrients, land stripped of its protective grasss cover
• So vegetation cannot re-establish itself
• Soil is exposed to wind and rain and increase in evaporation from soil leading to desertification

Question 5

Causes of desertification : Population Growth

Answer 5

• Farmers forced to change traditional methods of land use as more land needed for food crops, leads to overcultivation : reduced soil fertility and soil left exposed, leads to vegetation removed, leads to increase in evaporation from soil and increased risk of soil erosion, leading to desertification
• Increased demand for wood for cooking, heating and building leads to deforestation, vegetation removed and increased risk of soil erosion leading to desertification

Question 6

Areas at risk from desertification

Answer 6

• 1 billion people are at further risk from desertification and 12 million hectares of land annually are lost due to desertification

Question 7

Impacts of desertification on ecosystems

Answer 7

• Reduction in vegetation, leading to reduced habitats and increased competition
• Continual cropping decreases nutrient recycling
• Soil nutrients are lost through wind and water erosion
• Carbon sinks are reduced
• loss of biodiversity
• Food webs become fragile

Question 8

Impacts of desertification on landscape

Answer 8

• Increased erosion
• Increased number of sand dunes
• Increased sedimentation of rivers
• more sand storms
• vegetation damaged by ‘sandblasting’ winds

Question 9

Impacts of desertification on Populations

Answer 9

• Drylands populations are often socially and politically marginalised due to poverty and remoteness
• Forced migration
• Increased male outmigration
• Loss of traditional knowledge and skills
• Reduced availability of fuel wood leads to increased purchase of kerosene, with health issues
• Food shortages
• Reduced income from traditional economy
• Widespread rural poverty

Question 10

Predicted climate change and the potential impact

Answer 10

• Temperatures could increase by 0.3-0.5 degrees, leading to further increases in degraded land and deserts

Question 11

Alternative possible futures for local populations : Desertifcation and the future

Answer 11

• Poverty and poor agricultural practices will continue to be the main cause of desertification
• Relieving the human pressure on ‘at risk’ areas is key
• food insecurity, deforestation and land degradation are linked issues that cause desertification
• Climate is predicted to become not only warmer but also less predictable and more extreme, leading to increases in droughts and floods
• Local populations need direct help in the form of variety of solutions that are proactive, Make use of their local knowledge and improve their resilience

Question 12

Possible measures to prevent future desertification and restore degraded land

Answer 12

• Improve agricultural practices
• Invest in integrated land and water management techniques to protect soils and reduce over grazing
• Support science-driven agriculture through eg drought resistant crops
• Maintain vegetation to protect soils and re-establish soil fertility through the use of organic fertilisers
• Reduce clearance of shrubs and trees by developing non-wood energy supplies, which are naturally available in the drylands ecosystem e.g solar, biogas and wind power