Rising carbon dioxide at Higher Level: The same ideas as SL, with different cases: Indonesia's peat fires, the Cape Grim station, the rise of the USA and the Model T, China's growth and the UK's last coal power station. At HL, notice who emitted when: the countries that emitted most in the past are not the ones whose emissions are rising fastest today.
Practise this as you read
- Link every reason for rising emissions to burning more fossil fuel.
- Quote the Keeling curve with values: 280, 317 and 427 ppm.
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People add carbon dioxide faster than nature removes it: Anthropogenic carbon dioxide comes mostly from burning fossil fuels.
The points to remember
- Anthropogenic = caused by human activity.
- Burning fossil fuels (coal, oil, gas) for power, transport and industry: the largest source.
- Cement making releases CO2 from limestone as well as from the fuel burned.
- Deforestation: burning or rotting trees release their stored carbon...
- ...and the forest can no longer take CO2 in: a double impact.
- A source adds CO2 to the air; a sink takes it out (forests, oceans, soils, peat).
Sources (add CO2)
- Burning fossil fuels
- Deforestation and burning
- Cement production
- Respiration and decomposition
Sinks (take CO2 out)
- Forests (photosynthesis)
- Oceans (CO2 dissolves)
- Soils (organic matter)
- Peat bogs
Remember it as: Burn it, clear it, bake it: fuel, forests, cement.
Real example: in September and October 2015, fires burned through drained peat swamps in Indonesia. On many days, they released more CO2 than the whole US economy.
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How do we know the CO2 in the air is rising? It has been measured directly, every day, since 1958.
The points to remember
- CO2 has been measured at Mauna Loa, Hawaii, since 1958: the Keeling curve.
- It has risen every year: from about 317 ppm in 1960 to about 427 ppm in 2025.
- Before the Industrial Revolution it was about 280 ppm.
- The rise is speeding up: about 0.9 ppm a year in the 1960s, about 2.4 ppm a year in the 2010s.
- The yearly zigzag: CO2 falls in the northern summer as plants take it in, and rises in winter.
Real example: stations far from Hawaii show the same rise: Cape Grim in Tasmania, Australia, has sampled clean air blowing off the Southern Ocean since 1976.
The rise in CO2 can be traced back to one turning point: the Industrial Revolution.
The points to remember
- The rise began with the Industrial Revolution in late 18th-century Britain.
- Coal powered steam engines, factories and railways; in 1800, Britain made 96% of the world's fossil CO2.
- Industry spread through Europe and North America in the 1800s; by 1900, the USA emitted the most.
- In the 20th century, oil, cars and electricity spread across the world.
- World fossil CO2 emissions: about 2 billion tonnes a year in 1900, 5.9 in 1950, 38.6 in 2024.
- So the rate of emission accelerated, above all since 1950.
Real example: the USA became the biggest emitter around 1900. Cars spread fast: Ford built about 15 million of its Model T between 1908 and 1927, and by 1950 the USA made 43% of the world's fossil CO2.
Two dates to remember: Late 1700s: the rise begins (Britain, coal). After 1950: the great acceleration (the whole world).
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Why did emissions speed up so much after 1950? Each reason is a link: more of something that burns fossil fuel, so more CO2.
The points to remember
- Industrialization spreading to more countries: new factories and fossil-fuelled power plants.
- Population growth: about 2.5 billion people in 1950, about 8.2 billion in 2024.
- Rising standard of living: more cars, electricity, air travel and goods per person.
- Intensive, mechanized farming that runs on fossil fuels, in place of traditional farming.
- Burning forests to clear land for farms and cities.
- Some rich countries now emit less per person as they switch away from coal.
Real example: China's emissions rose from about 3.6 billion tonnes in 2000 to about 12.2 billion in 2023, about a third of the world total. Meanwhile the UK closed its last coal power station, Ratcliffe-on-Soar, in 2024.
A reason needs a link: 'China's economy' is half a reason. 'A rapidly growing economy means more fossil-fuelled power plants and factories, so more CO2' is a full reason.
Papers give a chart of emissions and ask for a percentage change or a mean yearly increase.
The points to remember
- Percentage change = (new - old) / old x 100.
- Mean yearly increase = (last value - first value) / number of years between them.
- Read values carefully from the graph, then show your working.
- Give the unit: %, ppm, or million tonnes of CO2 a year.
- A fall is a negative change: say 'a decrease of...'.
Percentage change
Germany per person: (7.0 - 11.0) / 11.0 x 100 = -36%, a decrease of 36%.
Mean yearly increase
Vietnam: (339.3 - 124.5) / (2019 - 2009) = 214.8 / 10 = about 21.5 million tonnes a year.
Check the years
From 2009 to 2019 is 10 years, not 11: count the gaps, not the dots.
Show it: Write the subtraction and the division, then the answer with its unit. A bare number can lose the mark.
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How this comes up: Paper 2, Section A: a chart of emissions per person in two years, then a percentage change [1] and 'Identify two possible reasons' for one country's change [2].
Countries are developing at different speeds. The figure shows the carbon dioxide emissions per person of six countries in 2000 and 2023.
Identify two possible reasons for the change in CO2 emissions per person for Saudi Arabia.
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