Desertification process (AOS-2)

Question 1

the spatial distribution of global land cover (define desertification)

Answer 1

desertification is the process by which fertile land becomes desert, typically as a result of drought, deforestation, or inappropriate agriculture

Question 2

spatial distribution of desertification during the LGM

Answer 2

• 20,000 years ago
  
  • Global mean temperature cooled by ~8◦C
  • Tropical land temperature cooled by ~2.6◦C
  • Sea level was 125 metres lower than present
• High latitude regions were drier than today, causing drought and desertification

Question 3

spatial distribution of desertification during the HCO

Answer 3

• 8,000 years ago
  
  • Increases of up to 4◦C near the North Pole
  • Sea levels rose by ~3 metres
• The Sahara desert was dotted with numerous lakes due to higher rainfall

Question 4

African Humid Period

Answer 4

• Occurred between 14,800 and 5,500 years ago
• Conditions in the Sahara were dominated by a strong North African Monsoon, resulting in larger annual rainfall totals compared to today’s conditions

Question 5

the distribution of desertification of a global scale

Answer 5

• 40% of the world is classified as dryland
• Drylands support 1/3 of the world’s population and 50% of the world’s livestock
• Desertification borders desert and dryland regions, making them more vulnerable to the process

Question 6

the nature of desertification as processes

Answer 6

• Desertification involves the reduced productivity of dryland regions, reduced land cover and increased erosion
  
  • Occurs at the margins of dryland areas (drylands are areas with growing seasons less than 179 days)
  • 12 million hectares of land per year are decertified
  • In 1991, a study suggested that 15% of the planet’s land was degraded
• 24% of land worldwide has been degraded because of human activity

Question 7

natural processes desertification

Answer 7

• Loss of vegetation cover: wood is a resource, grazing animals deplete vegetation, trees considered as competition to crops
  
  • Drought: if prolonged, it can cause desertification
  • Climate change: changing rainfall patterns, temperature stress on vegetation, soil erosions. Positive feedback of reduced vegetation cover increasing localised temperatures
• Excessive water: when added to soils it can cause rise in water tables and bring salts to the surface (salinity). Vegetation dies off and soil is degraded

Question 8

human processes desertification

Answer 8

• Population growth: the increase in people increases pressure on dryland areas as they will require more agricultural land to mitigate food insecurity
  
  • Poverty: in some areas people have no choice but to overcrop, overgraze and reduce the time soil has to recover between crops
  • Conflict: conflict can create a movement of refugees into degraded areas
• Governments: need to provide basic human needs so environmental needs get little attention for example, there are restrictions of nomadic farming which is a traditional farming method that moves grazing to match rainfall patterns and pasture (this restrictions leads to overgrazing)