The big idea: Desertification is the degradation of land in arid and semi-arid regions until it becomes desert-like.
What happens to the land
- The soil loses fertility.
- Vegetation dies back.
- The land can no longer support farming or grazing.
What it is not: It is not the natural spread of an existing desert. It happens at the dryland margins (e.g. the Sahel, just south of the Sahara) where a fragile environment is pushed over the edge by climate and human pressure working together.
What examiners want: This is a managing micro: examiners want the causes, the consequences, and how successfully they can be managed.
Key terms
- Desertification — land degradation in dryland margins that turns productive land desert-like.
- Arid / semi-arid — very dry / fairly dry climates where rainfall is low and unreliable.
- Land degradation — a long-term loss of soil fertility and vegetation cover.
- Overgrazing — keeping more animals than the land can support, stripping vegetation faster than it regrows.
- Salinisation — salt building up in the soil (often from poor irrigation), poisoning crops.
- Vulnerable land — dryland that is at risk of tipping into desertification.
Physical AND human causes: Desertification has a physical trigger (drought, falling and erratic rainfall, climate change) and a human accelerator (overgrazing, over-cultivation, deforestation, poor irrigation, conflict).
The two work together: a drought weakens the land, then human pressure tips it over. Strong answers always weave both together.
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How this is tested: A choropleth map or table of land at risk of desertification is a classic data stimulus in this option.
The two short command terms
- Identify the country (or region) with the most vulnerable land in a given category.
- Estimate what proportion of a country's land is at risk.
Read carefully: Read the key or the right column carefully and quote the units.
Read the key first. Which regions are darkest (most at risk) and lightest (least at risk)?
Interactive diagram
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Using the map above, identify the region with the highest share of land at risk, and estimate the share at risk in Central Asia.
Model answer plan
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Land area vulnerable to desertification in selected Asian countries (thousand km2)
| Country | Drylands / plains | Mountainous land | Total land area |
|---|---|---|---|
| Pakistan | 300 | 180 | 880 |
| Iran | 1,050 | 120 | 1,650 |
| Philippines | 22 | 8 | 300 |
| Mongolia | 1,200 | 90 | 1,560 |
Estimate = a quick percentage: To estimate a proportion, divide the vulnerable area by the total land area and turn it into a rough percentage. You do not need to be exact — a sensible figure within a tolerance band earns the mark.
Using the table above: (a) identify the country with the greatest area of mountainous land vulnerable to desertification; (b) estimate the proportion of the Philippines' total land area that is vulnerable.
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Examiners reward the mechanism — how a cause strips the land and speeds degradation. Name the cause, then trace the chain to bare, eroded soil.
Causes of desertification and how they work
| Cause | How it degrades the land |
|---|---|
| Overgrazing | Too many animals strip vegetation faster than it regrows -> bare soil is compacted and eroded by wind and rain |
| Over-cultivation | Continuous cropping exhausts soil nutrients -> the soil loses structure and blows or washes away |
| Deforestation / fuelwood | Cutting trees for fuel removes roots that bind soil and shade that keeps it moist -> erosion speeds up |
| Poor irrigation | Over-watering in dry heat leaves salt behind (salinisation) -> the poisoned soil can no longer grow crops |
| Drought & climate change | Falling, erratic rainfall and higher temperatures kill vegetation and dry the soil -> wind erosion follows |
| Population pressure / conflict | More people and instability force land to be over-used and divert care away from it -> faster degradation |
Answering an 'Explain' [3] on a cause
- Name the cause and show you understand it (e.g. overgrazing = vegetation removed faster than it regrows).
- Develop the chain — exposed soil is compacted, then eroded by wind and rain.
- Reach the outcome — the land becomes bare, infertile and unusable. 1 mark for the link + up to 2 for development.
Explain how overgrazing speeds up the process of desertification.
Model answer plan
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Always reach 'bare, eroded soil': Don't stop at 'too many animals'. Carry the chain to the end: overgrazing -> vegetation stripped -> soil exposed -> compacted and eroded -> land degraded. The development marks live in that chain.
Conflict as a hidden driver: Armed conflict accelerates desertification too. In parts of the Sahel (e.g. around Lake Chad), fighting diverts labour and money away from land care, forces people to crowd onto fragile land, and lets terraces and water systems fall into disrepair — so soil quality declines and farming collapses faster than it otherwise would.
Managing the causes and consequences: Management works on two fronts: the causes and the consequences.
Tackle the causes
- Better grazing rules
- Planting drought-resistant crops and trees
- Soil-conservation terraces
- Efficient drip irrigation
- Large schemes like the African Great Green Wall and China's Loess Plateau restoration
Tackle the consequences
- Food aid
- Alternative livelihoods
- Relocating people off the worst land
The hard part: The biggest cause — climate change — is global and beyond any one country's control, while local schemes are cheap but small.
Explain how armed conflict can increase the rate of desertification in a dryland region.
Model answer plan
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How this is tested — the [10] essay: Paper 1 Option C ends with a 10-mark essay, marked on markbands.
Three recurring versions on desertification
- Examine why it is accelerating (physical AND human causes)
- To what extent its causes can be managed
- Examine how to manage the causes and the consequences
Top band needs
- Accurate terms
- Named real drylands (Sahel, Great Green Wall, Loess Plateau, the Dust Bowl)
- A weighing of causes/strategies and scales
- A clear judgement
To what extent can the causes of desertification be successfully managed?
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.