HSC Geography › Human–Environment Interactions › 12.1

# Teacher Lesson Plan — Natural & Human-Induced Change

NSW Stage 6 Geography (2022) · Land cover change · ~70–80 min (flexible over 1–2 periods)
Teacher copy — includes model answers

## At a glance

### Companion resources

- Student study page
- Revision slides
- Activity handout (student, no answers)

### Big idea

Earth's systems have always changed, but human activity now dominates the rate of change — and natural + human drivers interact and amplify one another.

## Syllabus mapping (NESA Geography 11–12, 2022)

Focus area: Human–Environment Interactions · Content: land cover change — the nature and spatial distribution of natural and human-induced change to Earth's natural systems; evidence and causes of climate change.

### Outcomes addressed

GE-11-01 characteristics & spatial patterns GE-11-02 processes & influences across scales GE-11-03 opportunities/challenges & perspectives GE-11-05 analyses & synthesises sources GE-11-08 mathematical techniques (graph/data) GE-11-09 communicates understanding

Note on outcome codes: the old pipeline lesson used earlier labels (e.g. “GE11-2”). These have been re-mapped to the current 2022 codes above — verify against your school's scope & sequence.

### Key geographical concepts

environment change interconnection scale sustainability

## Lesson sequence & timings

Time | Phase | Teacher / student activity
--- | --- | ---
0–8 | Hook | Project the deck title slide (power station & cleared land). Turn-and-talk: “Is this scene natural or human-made? Both?” Surface the natural/anthropogenic distinction.
8–18 | Explicit teaching | Slides 3–7: two kinds of change, tipping points, deep-time cycles & proxies. Students annotate study-page §1–2.
18–28 | Guided practice | Activity 1 (sort the drivers) + Activity 3 (mechanism chain). Circulate; check the causal chain is complete.
28–40 | Data skill | Slides 9–10 + Activity 2 (read the CO₂ curve). Model reading a value off the axis; link to Skill 7.
40–55 | Analysis | Slides 13–14 + Activity 4 (spatial variation). Emphasise accounting for difference (mechanism, not just “it's hotter”).
55–70 | Evidence & apply | Slide 16 + Activity 5 (Australian evidence file — BoM/CSIRO). Set as directed research or homework.
70–80 | Consolidate | Recap slides; Activity 6 essay plan. Exit ticket: define tipping point in one sentence.

## Activities — model answers

### Activity 1 · Sort the drivers

Model
Natural: volcanic eruption, lightning bushfire, solar cycles, earthquake, Earth's axial tilt. Human-induced: burning coal, clearing forest, car exhaust, overgrazing, aerosol pollution. Both/depends: a lightning bushfire is a natural ignition, but its severity is worsened by human-driven warming and drought — a natural hazard amplified by anthropogenic change. That interaction is the point of the topic.

### Activity 2 · Read the CO₂ curve

Model
(1) ~285–290 ppm in 1850; over 420 ppm now. (2) ~140+ ppm increase from the ~280 ppm pre-industrial baseline. (3) “Steep” / “exponential” / “hockey-stick” — significant because the sharp post-1950 rise coincides with mass fossil-fuel use, pointing to a human driver. (4) Burning fossil fuels and deforestation.

### Activity 3 · Explain the mechanism

Model
Chain: burn fossil fuels → release CO₂ → enhanced greenhouse effect → heat trapped → lower atmosphere warms. One sentence: “Burning coal, oil and gas releases carbon dioxide, which enhances the greenhouse effect by trapping outgoing heat, warming the lower atmosphere.” Double hit: deforestation both releases the carbon stored in trees and removes a carbon sink, so less CO₂ is absorbed — emissions up, absorption down.

### Activity 4 · Spatial variation

Model
Arctic — faster (~4×): ice–albedo feedback (melting bright ice exposes dark, heat-absorbing ocean). Europe — faster (~2×, fastest-warming continent): circulation changes, land warms faster than ocean. India — slower: sulphate aerosols reflect sunlight (a harmful, temporary “mask”). East Antarctica — slower: ozone-hole-strengthened circumpolar winds and cold Southern-Ocean meltwater. Ice–albedo feedback: a self-reinforcing loop where melting ice lowers surface reflectivity, so more heat is absorbed, melting more ice.

### Activity 5 · Australian evidence file

Model (BoM/CSIRO State of the Climate 2022)
Air temperature: +1.47 °C since 1910. Sea-surface temperature: +1.05 °C since 1900. SW WA cool-season (Apr–Oct) rainfall: down ~15% since 1970. Extreme fire weather: increased, fire seasons longer. Accept the current edition's updated figures if students find a newer report — reward correct sourcing.

### Activity 6 · Essay plan

Model plan
Intro: define natural vs anthropogenic change; thesis = they interact, humans now dominate the rate. Body 1: natural drivers (orbital cycles, solar, volcanoes, succession) and timescales. Body 2: human drivers (fossil fuels → CO₂ mechanism; deforestation double-hit). Body 3: interaction/amplification — warming worsens drought/fire; Arctic ice–albedo feedback; tipping points; Australian BoM evidence. Conclusion: the Anthropocene idea — systems can no longer be studied in isolation.

## Key questioning (with answers)

- Q: If climate always changed naturally, how do we know today's change is human-caused?
  A: The rate is far faster than natural cycles; it tracks measured fossil CO₂ (with a distinct isotopic fingerprint); and climate models only reproduce observed warming when human emissions are included.
- Q: Why is the global average “misleading”?
  A: It hides large regional differences — the Arctic warms ~4× faster; some regions are temporarily masked by aerosols. Averages understate local risk.
- Q: Why is ocean acidification separate from warming?
  A: It is a direct chemical result of CO₂ dissolving in seawater and lowering pH — it would happen even without temperature rise, harming shell-builders and reefs.

## Differentiation & assessment

### Support

- Pre-fill one row of each table as a worked model.
- Provide the driver-sort cards cut out for physical sorting.
- Sentence starters for the mechanism chain.

### EAL/D

- Glossary pre-teach: anthropogenic, proxy, albedo, aerosol, tipping point.
- Pair the graph task; allow oral explanation before writing.

### Extension

- Debate: “There is no longer such a thing as a purely natural system.” (Anthropocene).
- Compare two proxy methods for reliability.
- Research the isotopic “fingerprint” evidence for fossil-carbon.

### Assessment / homework

- Complete the Activity 5 evidence file from the current BoM report.
- Write the full extended response planned in Activity 6.

## Useful resources & recent articles

- BoM/CSIRO — State of the Climate (the Australian evidence base; check for the latest edition)
- NOAA — Mauna Loa CO₂ trend (live current CO₂ value for Activity 2)
- NASA — Global temperature vital signs
- WMO — State of the Global Climate (warmest-year confirmations)
- IPCC AR6 (attribution & tipping points)

Live-data reminder: temperature and CO₂ figures move each year. Before teaching, refresh the CO₂ value (NOAA) and the “warmest year” status (WMO/Copernicus) so class data is current.
Rose Bay Secondary College · HSC Geography · Human–Environment Interactions — Teacher plan (12.1) · NESA Stage 6 (2022) · HSC 2026
Aligned to the NESA Geography Stage 6 Syllabus (2022); facts verified to public sources; figures redrawn (no textbook images reproduced).