These ten questions cover the five lessons in climate change evidence and responses. Questions 1 to 4 are easier, 5 to 8 need two steps, and 9 to 10 ask for written judgement. All data are invented for practice.
Write your answer first, then open the worked solution. Log slips in the mistake log and retest queue, and try small datasets in the statistics and distribution explorer.
1. Label each as observation (O) or attribution (A). (a) “Mean temperature rose from 21.4 °C to 21.9 °C.” (b) “The rise was caused by city growth.”
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(a) O: it can be checked against the data. (b) A: a cause needs evidence that the table does not hold.
2. Decade means at a station are 14.1, 14.3, 14.4 and 14.7 °C. Find the total rise and the average rise per decade.
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Total: 14.7 − 14.1 = 0.6 °C. Three gaps between four decades, so 0.6 ÷ 3 = 0.2 °C per decade. Check: 0.2 × 3 = 0.6.
3. Emissions rise from 250 to 275 million tonnes. Find the percentage change.
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275 − 250 = 25. Then 25 ÷ 250 = 0.1, so 10% increase.
4. Emissions fall from 80 to 68 million tonnes. Find the percentage change.
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68 − 80 = −12. Then 12 ÷ 80 = 0.15, so a 15% decrease.
5. A country emits 600 million tonnes and has 30 million people. Find the emissions per person, and then the new per person value if emissions rise to 660 million with 33 million people.
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Before: 600 ÷ 30 = 20 tonnes. After: 660 ÷ 33 = 20 tonnes. Both are 20 tonnes per person. Total rose by 10% (60 ÷ 600) and population rose by 10% (3 ÷ 30), so the per person value did not change.
6. Country M emits 100 million tonnes with 4 million people. Country N emits 150 million tonnes with 10 million people. Which has the larger total, and which the larger per person value?
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M per person: 100 ÷ 4 = 25 tonnes. N per person: 150 ÷ 10 = 15 tonnes. N has the larger total, M has the larger per person value. The ranking depends on the measure.
7. In a simple balance model the surface receives 70 units from the Sun and 30 units returned by the atmosphere. More greenhouse gas raises the returned amount to 36. State the old and new totals and what happens to surface temperature.
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Old total: 70 + 30 = 100. New total: 70 + 36 = 106. The surface receives more than it emits, so it warms until its emission rises to 106 and balance returns.
8. Explain in three linked steps how greenhouse gases keep the surface warmer.
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The surface absorbs shortwave radiation from the Sun and emits infrared radiation. Greenhouse gases absorb part of this infrared, then re-emit it in all directions. Some returns to the surface, so the surface stays warmer than it would without these gases.
9. A dune-planting scheme costs 12 million units and protects 4,000 residents. A tree-planting scheme costs 9 million units and absorbs 3,000 tonnes of carbon dioxide per year. Compare them neutrally, using at least two criteria.
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Dune scheme: 12,000,000 ÷ 4,000 = 3,000 units per resident protected. Tree scheme: 9,000,000 ÷ 3,000 = 3,000 units per tonne per year. The numbers match but the units differ. Sample answer: “The dune scheme is adaptation and benefits a specific population, while the tree scheme is mitigation with a shared global effect over time. Cost per unit cannot rank them because the benefits are different in kind.”
10. A student writes: “The data prove our country is not to blame, and our town will flood in 2040.” Identify two problems and rewrite one.
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Problem 1: “prove” and “blame” go beyond what data can show. Problem 2: a precise local forecast is unsupported unless local data are supplied. Rewrite: “Per person emissions for our country were lower than the average in the table, but the table does not allow a judgement of blame. Local flood risk would need local measurements or a regional projection with a stated range.”
If you got these wrong
- Questions 1, 10: wording and overreach. Revisit observed trend versus attribution and avoiding rankings and unsupported forecasts.
- Questions 2 to 6: calculation or choice of column. Revisit interpreting a supplied dataset.
- Questions 7, 8: mechanism steps out of order. Revisit explaining a physical mechanism.
- Question 9: criteria missing or opinion creeping in. Revisit comparing responses neutrally.
If one error type keeps repeating, one-to-one Geography tuition can target it directly.