HSC Geography · Human–Environment Interactions
12.2 Land Cover Change at a Global Scale
Deforestation · desertification · retreating ice · NESA Stage 6 (2022) · Revision deck
By the end you can…
Learning goals
- Define land cover change and its three global forms.
- Explain deforestation's double blow (biodiversity + carbon).
- Describe the desertification cycle (the Sahel).
- Account for retreating ice and why it matters.
- Evaluate the 2022 “30×30” agreement.
Section 1
What is land cover change?
Three global changes
Deforestation
Clearing tropical forest for farming, logging, roads.
Desertification
Dryland degrading to desert-like conditions.
Retreating ice
Glaciers & ice sheets melting at poles & peaks.
Each clusters by climate zone — and each is human–environment interaction at a global scale.
Deforestation: a double blow
Biodiversity loss
Habitats destroyed; species to extinction; ecosystems destabilised.
Carbon released
Stored carbon to the air and a carbon sink destroyed.
Cleared for cattle, soy, palm oil, logging, mining, roads — fastest in the tropics.
Case study: the Amazon
More than half the world's tropical rainforest
~17–20% cleared (mainly cattle & soy); a vast carbon store at risk of a dieback tipping point.
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The response
“30×30” — 2022
Kunming–Montreal Framework (COP15)
- ~196 governments; 23 targets.
- Flagship: protect 30% of land & oceans by 2030.
- Plus: restore ecosystems, cut harmful subsidies.
Evaluate it: near-universal & measurable, but voluntary — funding & enforcement are the test.
The desertification cycle
Affects over 100 countries; the Sahel is the classic case.
Case study: the Sahel
The semi-arid belt south of the Sahara
Drought + overgrazing + fuel-wood + population growth. Response: the Great Green Wall.
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Section 4
Retreating glaciers & ice
Ice in retreat
Kilimanjaro
>80% of ice lost since 1912.
Himalayas
“Third Pole” — rivers for ~2 billion people.
Greenland
Losing mass; raising sea levels.
Ice = freshwater store and sea-level driver — monitored from space (satellite imagery).
Big picture
The Anthropocene
A human-shaped planet
Land cover change is so widespread that human activity is now a planetary geological force — the case for a new epoch, the Anthropocene.
Debate: “There is no longer such a thing as a purely natural system.”
Pull it together
- Land cover change = deforestation, desertification, retreating ice.
- Deforestation = biodiversity loss + carbon double hit (Amazon).
- Desertification = a feedback cycle (the Sahel; Great Green Wall).
- Ice loss threatens freshwater & raises seas (Kilimanjaro, Greenland).
- Global response: 30×30 (2022) — evaluate its effectiveness.
Next: Chapter 13 — Climate Change.