Atmosphere & resources
The evolution and composition of the atmosphere, greenhouse gases and climate change, potable water and using the Earth’s resources.
Learn
Atmosphere & resources, explained point by point
Everything the GCSE specification expects you to be able to do, and how to actually do it - the same lesson a signed-in student studies from.
Describe how the atmosphere evolved and its composition today
Earth's early atmosphere was rich in carbon dioxide from volcanoes, with little oxygen. As oceans formed and plants and algae photosynthesised over billions of years, CO₂ fell and oxygen rose. Today the air is about 78% nitrogen, 21% oxygen and small amounts of other gases including CO₂ - a big change driven by living things.
Explain greenhouse gases and climate change
Greenhouse gases like carbon dioxide, methane and water vapour trap heat radiated from the Earth, keeping the planet warm enough to live on. Burning fossil fuels and clearing forests raise CO₂ levels, strengthening this effect and causing global warming. The likely results - rising sea levels and more extreme weather - are why cutting emissions matters.
Explain what a carbon footprint is and how to reduce it
A carbon footprint is the total greenhouse gases given off by a product, service or activity over its life. It can be reduced by using renewable energy, being more efficient, and cutting waste. Real-world limits - cost, convenience and lack of political will - often stand in the way, which is worth being able to discuss.
Describe common atmospheric pollutants and their effects
Burning fuels releases pollutants. Incomplete combustion produces carbon monoxide, a toxic gas, and soot particulates that harm lungs and cause global dimming. Sulfur impurities make sulfur dioxide, and high temperatures make nitrogen oxides - both cause acid rain and breathing problems. Knowing the source helps explain how to cut each one.
Describe how potable water is produced
Potable water is safe to drink - low in dissolved salts and microbes, though not chemically pure. In the UK, fresh water is filtered to remove solids and then sterilised with chlorine, ozone or UV to kill microbes. Where fresh water is scarce, seawater can be desalinated by distillation or reverse osmosis, which uses more energy.
Explain using and reusing Earth's resources, including recycling
The Earth's resources are finite, so we reduce, reuse and recycle to make them last. Recycling metals, glass and plastics saves raw materials and energy compared with making things new - recycling aluminium uses a small fraction of the energy of extracting it. A life cycle assessment weighs the full environmental cost of a product from cradle to grave.
Atmosphere & resources key terms
The words the specification and the mark schemes use, each defined the way an examiner wants it.
- Greenhouse gases
- Gases in the atmosphere, including carbon dioxide, methane and water vapour, that absorb outgoing long-wavelength radiation and keep the Earth warm.
- Carbon footprint
- The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
- Potable water
- Water that is safe to drink. It is not pure in the chemical sense, because it still contains dissolved substances.
- Desalination
- Removing salt from sea water to produce potable water, by distillation or reverse osmosis. Both need large amounts of energy.
- Finite resource
- A resource that is used faster than it forms, such as fossil fuels and metal ores.
- Renewable resource
- A resource that can be replenished as quickly as it is used, such as timber from managed forests.
- Life cycle assessment
- An assessment of the environmental impact of a product across its whole life: extracting raw materials, manufacture, use, and disposal.
Practice
Try a Atmosphere & resources question
A GCSE-style original question from this topic. Have a go before you open the working - deciding on an answer first is what makes the working stick.
A life cycle assessment for a plastic bag finds it releases 3 g of carbon dioxide during raw material extraction, 2 g during manufacturing and 1 g during transport. What is the total carbon dioxide from these stages, in g?
- 4
- 6
- 3
- 5
Show the answer and the working
Answer: 6
A life cycle assessment adds the emissions from each stage: 3 + 2 + 1 = 6 g.
- A life cycle assessment totals the emissions from every stage.
- The stages give 3 g, 2 g and 1 g.
- Add them: 3 + 2 + 1 = 6 g.