HSC Geography › Human–Environment Interactions › 13.2

# Teacher Lesson Plan — Causes of Climate Change

NSW Stage 6 Geography (2022) · Climate change · ~70 min
Teacher copy — includes model answers

## At a glance

### Companion resources

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

### Big idea

Natural causes (orbital cycles, volcanoes) can't explain the recent, rapid warming; human disruption of the carbon cycle and the enhanced greenhouse effect can — and the 800,000-year CO₂ record clinches it.

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

Focus area: Human–Environment Interactions · Content: climate change — the environmental (natural) and human causes of climate change.

### Outcomes addressed

GE-11-02 processes & influences across scales GE-11-01 characteristics & patterns GE-11-05 analyses sources GE-11-08 mathematical techniques GE-11-09 communicates

Outcome codes: source used GE-12-x; re-mapped to GE-11-x (Year 11 Preliminary). Verify against your scope & sequence.

### Key concepts

environment change interconnection scale

## Lesson sequence & timings

Time | Phase | Teacher / student activity
--- | --- | ---
0–8 | Hook | Deck title (volcano vs industry). “Which of these is driving today's warming?” Activity 1 (sort causes).
8–22 | Rule out nature | Slides 5–8: ice-age cycles & Pinatubo. Activity 2 (rule out) + Activity 3 (Pinatubo data).
22–38 | Carbon cycle | Slide 10 + Activity 4 (label the cycle). Emphasise net rise from fossil fuels + deforestation.
38–50 | Greenhouse | Slide 12: natural vs enhanced greenhouse. Address the misconception that “greenhouse effect” is inherently bad.
50–62 | The clincher | Slide 14 + Activity 5 (800,000-yr graph). This is the killer evidence.
62–70 | Consolidate | Activity 6 essay plan. Exit ticket: one reason nature can't explain today's warming.

## Activities — model answers

### Activity 1 · Sort the causes

Model
Natural: orbital cycles, volcanic eruptions, solar output, ocean circulation. Human: burning coal, deforestation, enhanced greenhouse effect, fossil-fuel transport.

### Activity 2 · Rule out natural

Model
Orbital cycles: far too slow and out of step with the orbital schedule. Volcanoes: cause short-term cooling, and their CO₂ is far less than human emissions. Solar output: has been roughly flat/slightly declining while temperatures rose — so it can't be the driver.

### Activity 3 · Pinatubo

Model
~20 million tonnes of SO₂; cooled Earth ~0.5 °C for 1–2 years. Cooling, because SO₂ and ash reflect sunlight. Volcanic CO₂ is a small fraction of human emissions, so it can't drive sustained warming.

### Activity 4 · Carbon cycle

Model
Photosynthesis; sink; fossil fuels; deforestation; net rise. Summary: humans add carbon (fossil fuels) faster than the sinks can remove it, and deforestation shrinks the sinks — so atmospheric CO₂ climbs.

### Activity 5 · 800,000-year graph

Model
Naturally CO₂ stayed below ~300 ppm; today it is over 420 ppm, spiking after ~1950. It's strong evidence because current CO₂ is outside the entire natural range of 800,000 years and the spike aligns with industrialisation — natural cycles can't produce it.

### Activity 6 · Essay plan

Model plan
Intro: define natural vs human causes. Rule out nature (cycles too slow; volcanoes cool & emit little CO₂; flat solar). Human causes: carbon-cycle disruption + enhanced greenhouse. Clincher: 800,000-yr CO₂ record. Conclusion: the evidence points clearly to a human cause.

## Key questioning (with answers)

- Q: “The climate has always changed — so why blame humans?”
  A: True, but the rate and size of today's change is unlike the natural record and matches industrialisation; natural drivers are ruled out by timing, direction and magnitude.
- Q: Isn't the greenhouse effect natural?
  A: Yes — and essential (keeps Earth ~33 °C warmer). The problem is the human enhancement of it.
- Q: Why is the 800,000-year graph so powerful?
  A: It shows CO₂ today is beyond anything in the natural range across many ice-age cycles — a level nature hasn't produced.

## Differentiation & assessment

### Support

- Provide cause cards to physically sort (Activity 1).
- Sentence frames for “rule out” explanations.

### EAL/D

- Pre-teach: orbital, sulphur dioxide, sink, sequester, enhanced.

### Extension

- Research the solar-output evidence (why the sun isn't the cause).
- Compare methane vs CO₂ as greenhouse gases.

### Assessment / homework

- Write the Activity 6 extended response in full.

## Useful resources & recent articles

- NASA — Evidence & causes
- USGS — volcanic vs human CO₂
- NOAA — CO₂ trend & ice-core record
- IPCC AR6 WG1 (attribution)

Accuracy reminder: Pinatubo cooling is usually cited as ~0.5 °C; volcanic-vs-human CO₂ ratios and current CO₂ update — cite sources.
Rose Bay Secondary College · HSC Geography · Human–Environment Interactions — Teacher plan (13.2) · 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).