Teacher sheet · Ages 15–16 · about 45–50 minutes
Climate change: the evidence and the numbers
Lesson page: echoesof.science/school/climate/ages-15-16/ · Pupil worksheet: echoesof.science/school/climate/ages-15-16/print/
Learning aims
- Define climate statistically and use Köppen thresholds.
- Explain the greenhouse effect, the main gases and the water-vapour feedback.
- Calculate rates of change from CO₂ and sea-level data and compare baselines.
- Summarise the IPCC's main conclusions and evaluate evidence and uncertainty.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: show two temperature anomalies with different baselines. Why do they differ? |
| 15 min | Read the text; worked examples: CO₂ rate and sea-level rate. |
| 15 min | Data investigation of the CO₂ record. |
| 5 min | Play Where is the evidence? |
| 5 min | Quiz and discussion of uncertainty. |
Materials for the experiment
- Graph paper or a spreadsheet
- Calculator
- The CO₂ values in the lesson text (313 ppm in March 1958; 410 ppm in 2019; 430.2 ppm in May 2025; 432.00 ppm in May 2026)
- Optional: the monthly Mauna Loa data from NOAA or Scripps
Safety: No practical hazards: this is a data investigation.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Weather and climate change are the same thing. | Climate is the 30-year statistics of weather; one cold winter says little about the long-term global trend. |
| Water vapour is the main driver, so CO₂ does not matter. | Water vapour responds to temperature as a feedback; CO₂ and other long-lived gases drive the change. |
| All melting ice raises sea level. | Floating sea ice does not; land ice and the thermal expansion of seawater do. |
Worksheet answers
- Rising curve from about 313 ppm to about 432 ppm, slightly steeper in recent decades, with a small yearly up-and-down: peak in May, minimum after the northern growing season. x-axis: year; y-axis: CO₂ (ppm).
- (432 − 410) ÷ about 7 years ≈ 3 ppm per year, higher than the 1958–2026 mean of about 1.75 ppm per year (note: 2019 is an annual value, 2026 a May peak).
- One cold winter in one place is weather. Climate is the average over about 30 years across the globe; global average temperature has risen about 1.1 °C since 1850–1900, and 2024 was the hottest year on record.
- Sea ice already floats and displaces its own weight of water, so its meltwater barely changes sea level; the Greenland ice sheet sits on land, so its meltwater adds new water to the ocean (complete melting would add about 7.4 m).
Quiz answers
- Mean rate of CO₂ rise from 313 ppm (1958) to 432 ppm (2026)? About 1.75 ppm per year. (432 − 313) ÷ 68 ≈ 1.75 ppm per year.[8]
- Sea level rose 0.20 m from 1901 to 2018. What is the mean rate? About 1.7 mm per year. 0.20 m ÷ 117 years ≈ 1.7 mm per year.[9]
- Why does CO₂ at Mauna Loa fall each northern summer? Growing plants take up CO₂. It falls during the Northern Hemisphere growing season.[8]
- Why can't you directly compare NASA's 1.19 °C (2025) with the IPCC's 1.1 °C? They use different baseline periods. NASA uses 1951–1980; the IPCC uses 1850–1900.[7][9]
- Why is water vapour called a feedback rather than a direct cause? Its amount rises as the climate warms, amplifying the warming. Warming increases water vapour, which traps more heat.[5]
- What does the IPCC say limiting human-caused warming requires? Net zero CO₂ emissions. Limiting warming requires net zero CO₂ emissions.[9]
Going further
Download the monthly Mauna Loa CO₂ record and NASA's annual global temperature anomalies. Plot temperature anomaly against CO₂ concentration, describe the relationship, and discuss why a correlation alone does not prove cause, and what other evidence the IPCC uses.
Sources used in this lesson
- [1] What is climate? (Met Office (UK national weather service)): reliability High
- [3] Climate zones (Met Office (UK national weather service)): reliability High
- [5] The Causes of Climate Change (NASA Science): reliability High
- [6] Evidence of Climate Change (NASA Science): reliability High
- [7] World of Change: Global Temperatures (NASA Earth Observatory): reliability High
- [8] Annual Carbon Dioxide Peak Reaches 432 Parts per Million (Scripps Institution of Oceanography, UC San Diego (with NOAA)): reliability High
- [9] AR6 Synthesis Report: Summary for Policymakers (Intergovernmental Panel on Climate Change (IPCC)): reliability High
- [11] Why ice sheets matter (National Snow and Ice Data Center (NSIDC), University of Colorado): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/climate/sources/
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