3.5Unit 5: Atoms, purity and climate

Atmosphere and climate — Cambridge Checkpoint Earth & Space 0893 Revision Notes & Topical Questions

5 min read 10 parts Lesson 5 of 5 1 quiz

📚 Cambridge Checkpoint Earth & Space 0893 Hub / Topical Revision

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Lesson summary

3.5 Atmosphere and climate — CHECKPOINT EARTH AND SPACE 0893 notes: Describe how the atmosphere changed, how humans add to the greenhouse effect and how renewable resources reduce global warming.Origin — about 4600 million years ago the Earth was molten, then cooled and formed a …

Composition about 4000 million years ago
Like Venus
Unsuitable
Microorganisms
Photosynthesis
Evidence for oxygen

Section 1 of 10The early atmosphere

1Origin

Origin about 4600 million years ago the Earth was molten, then cooled and formed a solid crust

2Volcanoes

Volcanoes much more volcanic activity than now produced the gases of the early atmosphere

3Water

Water water vapour from volcanoes condensed as the Earth cooled and fell as rain to form lakes and oceans

4Composition about 4000 million years ago

Composition about 4000 million years ago mainly carbon dioxide with little or no oxygen, small amounts of methane and ammonia and some water vapour

5Like Venus

Like Venus it resembled the atmosphere of Venus today

6Unsuitable

Unsuitable without oxygen it could not support animals

Section 2 of 10Atmosphere then and now

	Early atmosphere	Atmosphere today
Main gas	Carbon dioxide (about 95%)	Nitrogen (78%)
Oxygen	Little or none	Present (about a fifth)
Carbon dioxide	Very high	About 0.04%
Surface temperature	Above 400 °C	About 20 °C

Section 3 of 10How the atmosphere changed

Microorganisms

Microorganisms about 3500 million years ago they lived in the oceans and used carbon dioxide to make food, giving out oxygen

Plants

Plants they later grew on land and photosynthesis removed more carbon dioxide and added oxygen

Photosynthesis

Photosynthesis carbon dioxide + water → glucose + oxygen

Evidence for oxygen

Evidence for oxygen oxygen combined with iron in rocks to form iron oxide

Carbon dioxide

Carbon dioxide by 200 million years ago there was very little left

Locked-up carbon

Locked-up carbon it is in fossil fuels such as oil and coal and in limestone, which is made from the calcium carbonate shells of animals

Section 4 of 10Atmospheric changes today

Rise

Rise carbon dioxide fell until about 200 years ago and then began to rise

Fossil fuels

Fossil fuels humans burn oil and coal for heat, industry, transport and electricity, releasing carbon dioxide
- (carbon + oxygen → carbon dioxide)

Deforestation

Deforestation cutting down trees means less carbon dioxide is used in photosynthesis

Cattle

Cattle they produce carbon dioxide and methane

Limestone

Limestone using it to make cement releases carbon dioxide
- (calcium carbonate → calcium oxide + carbon dioxide)

Section 5 of 10Greenhouse effect and global warming

Greenhouse effect

Greenhouse effect gases such as carbon dioxide, methane and water vapour act like a blanket or greenhouse, trapping heat energy near the Earth

Needed

Needed without the greenhouse effect the Earth would be much colder

Increase

Increase more greenhouse gases mean less heat escapes, so the climate becomes warmer

Global warming

Global warming the warming of the Earth caused by rising greenhouse gases

Analogy

Analogy a comparison that explains an idea, such as the blanket or greenhouse

Section 6 of 10Greenhouse effect investigation

Put a thermometer into each of three bottles, with the bulb not touching the bottle.

Add carbon dioxide to the first bottle, about 5 cm³ of water to the second and leave the third with normal air.

Label the bottles and place them side by side outside or near a window.

Record the starting temperature in each bottle.

Record the temperatures over the next few days at chosen times.

Compare the results, using the normal-air bottle as a control.

Section 7 of 10Renewable resources

Renewable resource

Renewable resource one that does not run out or can be replaced within a human lifetime

Non-renewable resource

Non-renewable resource one that cannot be replaced after it is used, such as coal, petroleum and natural gas

Reason

Reason burning fossil fuels for electricity adds carbon dioxide, so more electricity should come from renewable sources

Wind

Wind wind farms make electricity with no harmful waste but only when the wind blows

Tidal

Tidal water released through turbines as the tide goes out makes electricity, but only at certain times and the barrier can harm wildlife habitats

Solar

Solar photovoltaic cells convert solar energy into electricity but only when the Sun is shining

Section 8 of 10Bioplastics

Problem

Problem plastics do not break down easily and waste builds up on land and in the oceans

Bioplastic

Bioplastic a biodegradable material made from renewable sources such as vegetable oils, sawdust or food waste

Benefit

Benefit it reduces the use of fossil fuels and the damage from single-use plastics

Section 9 of 10Key terms

Term	Meaning
Atmosphere	Layer of gas above the Earth's surface.
Greenhouse effect	Trapping of heat by gases in the atmosphere.
Global warming	Rise in the Earth's temperature from more greenhouse gases.
Fossil fuel	Fuel such as coal, oil or gas made from long-dead organisms.
Renewable resource	Resource that does not run out.
Deforestation	Cutting down large areas of forest.
Bioplastic	Biodegradable plastic from renewable materials.

Section 10 of 10Exam technique

Thinking the greenhouse effect is always harmful — without it the Earth would be much colder.

Thinking oxygen was always in the atmosphere — it was produced by photosynthesis.

Thinking all carbon dioxide comes from cars — burning fossil fuels, deforestation and making cement also add it.

Thinking renewable energy produces carbon dioxide in generation — wind, tidal and solar produce none.

Last updated: 12 October 2026