Reducing human impacts at Higher Level: The same measures as SL, with different examples: Norway's electric cars, Sweden's carbon tax, Indonesia's peatlands and Iceland's Orca plant. At HL, link each measure to law (agreements, bans) and economics (taxes, trading), and evaluate it.
Practise this as you read
- Link each measure to a store or flow of the carbon cycle.
- Evaluate: a strength, a weakness and a judgement.
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The carbon cycle is out of balance: People release carbon much faster than natural sinks can absorb it, and we damage the sinks themselves. Measures are needed to put the balance back.
The points to remember
- Burning fossil fuels releases carbon stored for millions of years in just decades.
- Sinks (oceans, forests, soils) absorb only about half; the rest builds up in the atmosphere.
- CO₂ has risen from 280 ppm before industry to over 420 ppm today.
- We also damage the sinks: cutting forests and draining peat release their carbon.
- So measures must cut what goes in, keep the stores and capture more.
Remember it as: Cut it, keep it, capture it.
Cut what goes in
- Low-carbon technologies
- Burn less fossil fuel: taxes, trading, laws
Keep and capture
- Protect forests, peat and soils
- Reforestation and artificial sequestration
Real example: in 2023 people released about 37 billion tonnes of CO₂ from fossil fuels and cement, the highest ever, even as renewable energy grew fast.
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The first measure is to make energy without burning coal, oil and gas: low-carbon technologies.
The points to remember
- Renewable energy (wind, solar, hydro, geothermal) makes electricity without burning fossil fuels.
- Nuclear power makes electricity with very low carbon emissions.
- Electric vehicles and public transport cut oil burned for travel.
- Energy efficiency (insulation, LED lights) means less energy, so less fuel is burned.
- Each works because less fossil fuel is burned, so less carbon moves from the lithosphere to the air.
Say how it works: In an outline, give the measure AND why it helps: 'wind turbines make electricity without burning coal, so less CO₂ is released', not just 'renewable energy'.
Real example: in Norway, nearly 9 in 10 new cars sold in 2024 were fully electric, and most of Norway's electricity comes from hydropower, so the cars run almost carbon-free.
Governments can make burning fossil fuels cost more, or cap it by law: a carbon tax, carbon trading, and international agreements.
The points to remember
- A carbon tax makes fossil fuels cost more, so people and firms use less or switch.
- Carbon trading caps total emissions; firms that cut emissions can sell permits.
- The Paris Agreement (2015): countries aim to keep warming well below 2 °C, ideally 1.5 °C.
- Each country sets its own pledge (NDC) and updates it every five years.
- People can help: less meat, less food waste, less travel by car and plane.
Carbon tax
- A fixed price per tonne
- Emissions fall as fuel costs more
- Money raised can fund green energy
Carbon trading
- A cap on total emissions
- Firms buy and sell permits
- The cap is lowered each year
Real example: Sweden has taxed carbon since 1991 and its tax, over 100 euros per tonne of CO₂, is among the highest in the world. Its emissions have fallen by about a third since 1990 while its economy grew.
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Forests, soils and peatland already hold huge amounts of carbon. Keeping it there is often cheaper than capturing it again later.
The points to remember
- Stop deforestation: standing forests keep their carbon out of the air.
- Protect and restore peatlands and wetlands: never drain them.
- Reduce soil disruption: less ploughing (no-till), cover crops, compost (see 2.3.8).
- Protected forests, peat and soils also keep absorbing CO₂: they stay sinks.
- These need laws, enforcement and money for the people who own the land.
Link it to the carbon cycle: Say which store keeps its carbon: 'protecting the forest keeps carbon in the trees and soil, so it is not released as CO₂ by burning or decomposition'.
Real example: after peat fires in Indonesia in 2015 blanketed South-East Asia in smoke, the government banned new clearing of peatland and set up an agency in 2016 to re-wet 2 million hectares of drained peat.
The third group takes carbon back out of the air: reforestation, and artificial sequestration such as carbon capture and storage and direct air capture.
The points to remember
- Reforestation and afforestation: growing trees absorb CO₂ by photosynthesis and store it in wood.
- Carbon capture and storage (CCS): CO₂ from chimneys is buried in rock deep underground.
- Direct air capture ('artificial trees') pulls CO₂ from the air to store it.
- Pros: CO₂ in the air falls, and CCS lets fossil fuels be used during the switch.
- Cons: high cost and energy, few storage sites, and it does not tackle the root cause.
- Trees can burn or be cut down, releasing the carbon again.
- Revegetating bare land and cities (parks, green roofs) also absorbs CO₂.
Reforestation
- Cheap and natural
- Also gives habitat and stops erosion
- Slow: trees take decades to grow
- Carbon lost again if the forest burns
Carbon capture (CCS)
- Traps CO₂ at the chimney
- Lets fossil fuels be used for now
- Expensive, uses extra energy
- Does not fix the root cause
Real example: On China's Loess Plateau, millions of trees and shrubs were planted on bare, eroded hills from 1999. In Iceland, the Orca direct air capture plant (2021) can capture about 4000 tonnes of CO₂ a year: about three seconds' worth of the world's yearly emissions.
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How this comes up: Paper 2, Section A: evaluate one strategy to reduce the impact of human activities on the carbon cycle [3]: a strength, a weakness and a judgement.
The Longship project in Norway captures carbon dioxide from a cement works and stores it under the North Sea.
Evaluate carbon capture and storage as a strategy to reduce the impact of human activities on the carbon cycle.
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