Desertification

The degradation of land in arid areas by which fertile land becomes desert like

• 75 billion tonnes of soil eroded annually

Human Causes:

• Overgrazing
  • Reduces vegetation > soil erosion (due to lack of plant roots)
  • Trampling by animals > compressed & breaks down structure of soil > erosion more likely
• Overcultivation:
  • Reduces soil productivity > without plants > soil is easily eroded
• Irrigation:
  • Depletes surface water and may involve unsustainable pumping of aquifers. As water levels are lowered, water availability for plants decreases, leading to soil erosion.
  • Surface irrigation= large amounts of water added to soil quickly, washing topsoil away
  • Too much water to irrigate crops = excess sink into soil and raise groundwater levels.
    • If aquifer saline, may bring high conc. of salt close to the surface, increasing salinity

Impacts of Desertification

• Landscapes: The ground surface becomes more prone to erosion because:
  • Vegetation slows wind speed, so reducing vegetation cover increases wind speed.
  • Moisture evaporates from soil more quickly when it isn’t sheltered by plants, so it dries out.
  • Plant roots that help to bind the sediment together are lost.
  • Higher wind speeds = more mobile sediment can also = more sand to be blown into an area
• Ecosystems:
  • Land less fertile, less plant life > reduces amount of organic matter that is put into the soil > further reducing vegetation growth. Less vegetation > less animal supported > – biodiversity
  • Distribution of species. Plant & animal may die out or migrate to less degraded areas.
  • Releases carbon stored in soil into atmosphere > climate change > widespread impact
• Populations:
  • Reduction in the fertility of land > decline in agricultural productivity= migrate from the area >
    • Often people migrate from rural to urban areas > may lead to overcrowding.
  • Human health in other ways, e.g. dust from soil erosion can = respiratory diseases

Future Climate Change Impact:

• Semi-arid areas to become hotter and drier- More extreme weather events, such as heat waves
• Global temperatures are expected to rise up to 6 degrees between 2015 and 2100.

Future for Locals: uncertainty surround the potential strategies

• Depends mitigation of impacts of and prevent more land from being degraded.

Futures for Desertification:

• Desertification may continue:
  • If action isn’t taken to reduce desertification, or if strategies aren’t funded or managed
  • Decrease in agricultural yields > increase malnutrition and famine = hinder development
  • May be conflict within and between countries as food and water becomes more scarce
• Humans may stop or reverse desertification:
  • LOCAL: People plant vegetation to bind the soil and act as windbreaks. Farmers can carry out crop rotation to allow the soil to recover, and improve irrigation systems.
  • GLOBAL: responses to climate change could have a major effect. However, this would require major commitment and cooperation around the globe.
• Humans may reduce the impacts of desertification:
  • Local populations may change their lifestyles in order to adapt and reduce its impacts.
  • g. local farmers could change their farming methods E.g. keeping small livestock such as goats and chickens, which would be less affected by desertification than crops
  • Improvements in agricultural technology = increase food they produce per hectare