KS3 Science Study Pack: Earth and Atmosphere

Key Knowledge

Earth is a layered planet surrounded by a mixture of gases called the atmosphere. This topic links chemistry, physics, biology and geography because it explains what Earth is made from, how air supports life, how carbon moves between different stores, why Earth is warm enough for living things, how human activity is changing the climate, and how rocks change over long periods of time.

The most important ideas are:

• Earth is approximately spherical and has layers: crust, mantle, outer core and inner core.
• The atmosphere is held around Earth by gravity.
• Dry air is mostly nitrogen, with oxygen making up about one fifth.
• Carbon dioxide is only a very small percentage of air, but it is important because it is a greenhouse gas.
• The natural greenhouse effect keeps Earth warm enough for life.
• Extra greenhouse gases from human activities strengthen the greenhouse effect and raise average global temperature.
• Carbon moves through the atmosphere, living things, oceans, soils, rocks and fossil fuels.
• Rocks form, break down, move and change through the rock cycle.
• Environmental decisions should be judged using evidence, benefits, limitations, cost, reliability, scale and fairness.

What Is Earth Made Of?

Earth is approximately spherical. It is not a perfect sphere because it is slightly wider at the equator than from pole to pole, but a sphere is a useful KS3 model.

Earth is made of layers:

Layer	What it is like	Important idea
Crust	Thin, solid outer layer	This is the layer we live on and where surface rocks are found.
Mantle	Very thick layer of hot, mostly solid rock	It can slowly flow over very long time scales.
Outer core	Dense, very hot metal-rich layer	Usually described at KS3 as liquid.
Inner core	Dense central part of Earth	Usually described at KS3 as solid because of very high pressure.

The crust is much thinner than the mantle. Most classroom diagrams are not to scale because a true scale diagram would make the crust almost too thin to see. Scientists often use models to make important features clear, but every model has limitations.

        crust
     .----------.
   .'            '.
  /    mantle      \
 |                  |
 |    outer core    |
 |      inner       |
 |      core        |
  \                /
   '.            .'
     '----------'

Diagram Interpretation: Earth Structure

1. Which labelled layer is the thinnest?
2. Which layer is a very thick layer of hot, mostly solid rock?
3. Why is this diagram probably not to scale?
4. How is Earth structure connected to rocks at the surface?

Model Answers

1. The crust is the thinnest layer.
2. The mantle is a very thick layer of hot, mostly solid rock.
3. It is probably not to scale because the crust is shown thick enough to see clearly, even though it is very thin compared with the mantle.
4. Surface rocks are part of the crust. Weathering, erosion, volcanoes, sediment formation and other rock cycle processes change rocks in the crust.

What Is the Atmosphere?

The atmosphere is the layer of gases around Earth. It is held close to Earth by gravity. Gravity pulls gas particles towards Earth, so the gases do not simply escape into space.

The atmosphere becomes thinner with height. Most air is close to the surface, where gravity's pull keeps gas particles more crowded together. This is why there is less oxygen available high on mountains.

Dry air means air without water vapour counted. Dry air is approximately:

Gas in dry air	Approximate percentage	Role or importance
Nitrogen	78%	Main gas in air; mostly unreactive in normal conditions.
Oxygen	21%	Needed for aerobic respiration and combustion.
Argon	0.9%	Unreactive gas present in a small amount.
Carbon dioxide	0.04%	Needed for photosynthesis and important in the greenhouse effect.
Other gases	Trace amounts	Include gases found in very tiny amounts.

Water vapour is also found in air, but its amount varies depending on place and weather. Warm, humid air contains more water vapour than cold, dry air.

Dry air composition (approx.)

Nitrogen        | ################################################## 78%
Oxygen          | #############                                      21%
Argon           | #                                                  0.9%
Carbon dioxide  | very small amount                                  0.04%
Other gases     | trace amounts

Worked Example: Interpreting Atmosphere Composition

Question: Use the table to answer these questions.

1. Which gas is most common in dry air?
2. Which gas is needed for aerobic respiration?
3. How much more nitrogen is there than oxygen?
4. Why can carbon dioxide matter even though it is only about 0.04% of dry air?

Worked answer:

1. Nitrogen is the most common gas in dry air.
2. Oxygen is needed for aerobic respiration.
3. Nitrogen is about 78% and oxygen is about 21%. There is about 57 percentage points more nitrogen than oxygen.
4. Carbon dioxide can still matter because some gases have important effects even in small amounts. Carbon dioxide absorbs some infrared radiation, so it contributes to the greenhouse effect.

Why the Atmosphere Matters

The atmosphere is essential for life and for conditions on Earth.

Oxygen is needed by humans and many other organisms for aerobic respiration. Respiration is a chemical process in cells that releases energy from food. It is not the same as breathing. Breathing moves air in and out of lungs; respiration happens inside cells.

Carbon dioxide is needed by plants and algae for photosynthesis. In photosynthesis, plants use light energy to make glucose from carbon dioxide and water. Oxygen is released as a product.

Nitrogen is the main gas in air. It is not very reactive under normal conditions, so it dilutes oxygen and helps make the atmosphere more stable. Nitrogen is also part of important compounds in living things, although most organisms cannot use nitrogen gas directly.

Water vapour is involved in weather. It can evaporate, condense into clouds, and fall as rain, snow or hail. The amount of water vapour changes from day to day and from place to place.

The atmosphere also helps protect living things. It absorbs some harmful radiation from the Sun, especially through the ozone layer. It also burns up many small meteoroids before they reach the ground.

The ozone layer and greenhouse gases are different ideas. The ozone layer absorbs much ultraviolet radiation. Greenhouse gases absorb infrared radiation. The ozone hole does not simply cause global warming.

The Natural Greenhouse Effect

The greenhouse effect is a natural process that keeps Earth warmer than it would otherwise be. Without it, Earth would be much colder and life as we know it would be difficult.

A greenhouse gas is a gas that absorbs some infrared radiation emitted by Earth's surface. Important greenhouse gases at KS3 include water vapour, carbon dioxide, methane and nitrous oxide.

The greenhouse effect happens in steps:

1. Sunlight passes through the atmosphere.
2. Earth's surface absorbs energy and warms up.
3. The warm surface emits infrared radiation.
4. Greenhouse gases absorb some of this infrared radiation.
5. Greenhouse gases re-emit radiation in different directions.
6. More energy remains in the Earth system, so the average temperature is higher.

      Sun
       |
       v  sunlight
  ------------------- atmosphere
       |
       v
   Earth's surface warms
       |
       v  infrared radiation
  greenhouse gases absorb and re-emit some radiation
       |
       v
  more energy stays in the Earth system

Important Comparison: Atmosphere and Garden Greenhouse

A garden greenhouse and the atmosphere both help keep things warmer, but they do not work in exactly the same way.

A garden greenhouse mainly traps warm air by reducing air movement. The atmospheric greenhouse effect mainly works because greenhouse gases absorb and re-emit infrared radiation. The greenhouse model is useful, but it is limited.

Diagram Interpretation: Greenhouse Effect

1. What type of radiation reaches Earth from the Sun?
2. What does Earth's warm surface emit?
3. What do greenhouse gases do to some infrared radiation?
4. Why is the natural greenhouse effect useful?

Model Answers

1. Sunlight reaches Earth from the Sun.
2. Earth's warm surface emits infrared radiation.
3. Greenhouse gases absorb and re-emit some infrared radiation.
4. The natural greenhouse effect keeps Earth warm enough for life.

Enhanced Greenhouse Effect and Climate Change

The natural greenhouse effect is not bad. The problem is the enhanced greenhouse effect. This happens when greenhouse gas concentrations increase, so more infrared radiation is absorbed and re-emitted.

Human activities that increase greenhouse gas concentrations include:

• burning coal, oil and gas in power stations, vehicles, boilers and factories;
• deforestation, because fewer trees are left to absorb carbon dioxide by photosynthesis;
• cement production, which releases carbon dioxide during chemical processes and uses energy;
• intensive farming, which can release methane and nitrous oxide;
• some industrial processes.

Global warming means the rise in Earth's average global temperature. Climate change includes global warming and wider changes such as altered rainfall patterns, melting ice, sea level rise, more frequent heatwaves in some regions, and impacts on ecosystems and people.

Weather is short-term atmospheric conditions, such as today's temperature, rainfall and wind. Climate is the long-term pattern of weather, usually considered over many years.

Feature	Weather	Climate	Example
Time scale	Hours, days or weeks	Many years	Weather: it rained yesterday. Climate: the UK usually has mild, wet winters.
What it describes	Short-term conditions	Long-term patterns	Weather: a cold morning. Climate: average winter temperatures.
Evidence	Forecasts and daily measurements	Long records and averages	Weather station readings today; 30-year rainfall averages.

Worked Example: Weather or Climate?

Classify each statement.

Statement	Weather or climate?	Reason
It rained in Manchester yesterday.	Weather	It describes one place on one day.
The UK usually has mild, wet winters.	Climate	It describes a long-term pattern.
Today is windy at the school field.	Weather	It describes current conditions.
Deserts usually receive very little rainfall.	Climate	It describes a long-term pattern for a region.

Cause-and-Effect Chain

One useful way to explain climate change is to write a chain:

Burning fossil fuels releases carbon dioxide -> carbon dioxide concentration in the atmosphere increases -> more infrared radiation is absorbed and re-emitted by greenhouse gases -> more energy remains in the Earth system -> average global temperature rises -> climate patterns change.

Climate change can increase the risk or frequency of some events, such as heatwaves in some regions or heavier rainfall in some places. It does not mean every weather event has one simple cause, and it does not mean every place gets hotter every day.

Greenhouse Gases

Greenhouse gas	Common sources	Why it matters
Water vapour	Evaporation from oceans, lakes, rivers and soils	Important natural greenhouse gas; amount varies with weather and temperature.
Carbon dioxide	Respiration, decomposition, combustion, volcanoes, burning fossil fuels, deforestation, cement production	Long-lasting greenhouse gas; extra from human activity strengthens the greenhouse effect.
Methane	Farming, landfill, fossil fuel extraction, wetlands	Powerful greenhouse gas, released by both natural and human sources.
Nitrous oxide	Farming, fertilisers, some industrial processes, soils	Greenhouse gas released in smaller amounts but important.

Greenhouse gases are not all from humans. Some come from natural processes. However, human activities have increased the concentration of several greenhouse gases, especially carbon dioxide from burning fossil fuels.

The Carbon Cycle

Carbon is an element found in many places. A carbon store is a place where carbon is kept. A carbon transfer is a process that moves carbon from one store to another.

Carbon stores include:

• atmosphere, mainly as carbon dioxide;
• plants, animals and microorganisms;
• soils;
• oceans;
• fossil fuels such as coal, oil and gas;
• carbonate rocks such as limestone.

Important carbon transfers include photosynthesis, feeding, respiration, decomposition, combustion, fossil fuel formation, dissolving in oceans and formation of carbonate rocks.

             carbon dioxide in air
              ^      ^       |
              |      |       | photosynthesis
   combustion |   respiration v
        fossil fuels       plants
              ^              |
              |              v feeding
       long-term stores    animals
              ^              |
              |              v death and waste
          rocks and soil <- decomposers

Carbon Cycle Processes

Process	Adds carbon dioxide, removes it, or transfers carbon?	Short explanation
Photosynthesis	Removes carbon dioxide from the atmosphere	Plants and algae take in carbon dioxide to make glucose.
Feeding	Transfers carbon	Carbon in food moves from one organism to another.
Respiration	Adds carbon dioxide to the atmosphere	Cells release energy from food and produce carbon dioxide.
Decomposition	Usually adds carbon dioxide and transfers carbon to soil	Decomposers break down dead organisms and waste.
Combustion	Adds carbon dioxide to the atmosphere	Burning fuels releases carbon dioxide.
Fossil fuel formation	Transfers carbon into long-term stores	Carbon from organisms can become coal, oil or gas over millions of years.
Dissolving in oceans	Removes carbon dioxide from atmosphere or transfers it back	Carbon dioxide can dissolve in seawater and can also be released again.
Carbonate rock formation	Transfers carbon into long-term rock stores	Carbon can become part of rocks such as limestone.

Worked Example: Tracing a Carbon Atom

Pathway 1:

1. A carbon atom is in carbon dioxide in the air.
2. A plant takes in the carbon dioxide during photosynthesis.
3. The carbon becomes part of glucose in the plant.
4. A rabbit eats the plant, so the carbon is transferred by feeding.
5. Cells in the rabbit respire, releasing carbon dioxide back to the air.

Pathway 2:

1. A carbon atom is stored in coal formed from organisms that lived millions of years ago.
2. The coal is burned in a power station.
3. Combustion releases carbon dioxide.
4. The carbon atom returns quickly to the atmosphere as carbon dioxide.

Burning fossil fuels is important because it transfers carbon from long-term stores into the atmosphere much faster than natural processes usually would.

Diagram Interpretation: Carbon Cycle

1. Name one process that removes carbon dioxide from the air.
2. Name two processes that add carbon dioxide to the air.
3. Is a plant a carbon store or a carbon transfer?
4. Why does burning fossil fuels affect the atmosphere?

Model Answers

1. Photosynthesis removes carbon dioxide from the air.
2. Respiration and combustion add carbon dioxide to the air. Decomposition can also add carbon dioxide.
3. A plant is a carbon store because carbon is held in its tissues.
4. Burning fossil fuels releases carbon dioxide from long-term stores into the atmosphere quickly.

Rocks and the Rock Cycle

A rock is a naturally occurring material made of minerals. A mineral is a naturally occurring solid substance with a particular composition and structure.

There are three main rock groups at KS3:

Rock type	How it forms	Common features	Example
Igneous rock	Molten rock cools and solidifies	Crystals; large crystals if cooling is slow, small crystals if cooling is fast	Granite, basalt
Sedimentary rock	Layers of sediment are compacted and cemented	Layers, grains, sometimes fossils	Sandstone, limestone
Metamorphic rock	Existing rock is changed by heat and pressure without melting	Distorted bands, hard texture, changed crystals	Slate, marble

Magma is molten rock below Earth's surface. Lava is molten rock at Earth's surface. Granite can form when magma cools slowly underground, making large interlocking crystals. Basalt can form when lava cools quickly at the surface, making smaller crystals.

Sedimentary rocks form when weathered fragments are transported, deposited in layers, compacted and cemented. Limestone may contain fossils. Sandstone forms from sand grains compacted and cemented together.

Metamorphic rocks form when existing rocks are changed by heat and pressure without fully melting. Slate can form from shale.

        magma / lava
             |
          cooling
             v
        igneous rock
             |
 weathering and erosion
             v
          sediment
             |
 compaction and cementation
             v
      sedimentary rock
             |
      heat and pressure
             v
      metamorphic rock
             |
          melting
             v
        magma / lava

The rock cycle is not one fixed route. Processes can happen in different orders over very long time periods.

Weathering, Erosion, Transportation and Deposition

Process	Meaning	Example
Weathering	Rock is broken down in place	Rainwater and ice widen cracks in a cliff face.
Erosion	Rock fragments are moved away	A river carries rock fragments away from a cliff.
Transportation	Sediment is moved by water, wind or ice	Sand is carried along a river bed.
Deposition	Sediment is dropped	Sand settles when a river slows down.

Cliff face
   |
   | cracks widen by weathering
   v
rock fragments at base
   |
   | moved by river, sea, wind, or ice = erosion
   v
sediment transported elsewhere

Worked Example: Identifying Rock Type from Evidence

Description	Rock type	Evidence
Large interlocking crystals formed by slow cooling underground	Igneous	It formed from cooling molten rock; slow cooling gives large crystals.
Visible layers and possible fossils	Sedimentary	Layers and fossils are common in sedimentary rocks.
Distorted bands from heat and pressure	Metamorphic	Heat and pressure changed the rock without melting it.

Worked Example: Weathering and Erosion

Rainwater enters cracks in a cliff. In cold weather the water freezes, expands and makes the cracks wider. Pieces of rock break off but remain at the bottom of the cliff. This is weathering because the rock is broken down in place.

Later, a river or the sea carries the fragments away. This is erosion because rock material is moved away from its original position. If the fragments are then carried along, this is transportation. If they are dropped when the water slows, this is deposition.

Environmental Data and Decision-Making

Scientists use data to study atmosphere, climate and environmental change. Data can show patterns, but conclusions should be cautious and evidence-based.

Data Task 1: Carbon Dioxide and Temperature

The table shows simplified global data. Carbon dioxide concentration is measured in parts per million, or ppm. A temperature anomaly shows how much warmer or cooler a year is compared with a chosen average baseline.

Year	Carbon dioxide concentration in ppm	Global temperature anomaly in degrees C
1960	317	-0.02
1980	339	0.12
2000	370	0.39
2010	390	0.72
2020	414	1.01
2025	423	0.95

Text graph:

Carbon dioxide concentration
1960 317 ppm | ###############################
1980 339 ppm | ##################################
2000 370 ppm | #####################################
2010 390 ppm | #######################################
2020 414 ppm | #########################################
2025 423 ppm | ##########################################

Temperature anomaly
1960 -0.02 | near baseline
1980  0.12 | #
2000  0.39 | ####
2010  0.72 | #######
2020  1.01 | ##########
2025  0.95 | #########

Questions:

1. Describe the trend in carbon dioxide concentration from 1960 to 2025.
2. Describe the trend in temperature anomaly from 1960 to 2025.
3. Quote two values from the table to support your answer.
4. Identify one possible anomaly or unexpected value.
5. Does correlation alone prove that carbon dioxide causes warming?
6. Explain the known scientific mechanism linking carbon dioxide to warming.

Model answers:

1. Carbon dioxide concentration increased from 317 ppm in 1960 to 423 ppm in 2025.
2. The temperature anomaly generally increased, from -0.02 degrees C in 1960 to 0.95 degrees C in 2025.
3. In 1960, carbon dioxide was 317 ppm and the anomaly was -0.02 degrees C. In 2020, carbon dioxide was 414 ppm and the anomaly was 1.01 degrees C.
4. 2025 could be described as an anomaly because carbon dioxide is higher than in 2020 but the temperature anomaly is slightly lower in this simplified dataset.
5. Correlation alone does not prove cause. Scientists also need a mechanism and many lines of evidence.
6. Carbon dioxide is a greenhouse gas. It absorbs and re-emits some infrared radiation emitted by Earth's surface, so more energy remains in the Earth system and average global temperature rises.

Data Task 2: Environmental Solutions for a Town

A town wants to reduce emissions. The table gives simplified evidence.

Solution	Benefit	Limitation	Best scale of use	Evidence students can use in an answer
Home insulation	Reduces energy needed for heating	Upfront cost and disruption	Houses, schools and public buildings	Could cut heating emissions by about 20% in improved homes.
Wind power	Generates electricity with very low direct carbon dioxide emissions	Output changes with wind conditions	Regional or national electricity supply	One medium wind project could supply thousands of homes.
Tree planting	Removes carbon dioxide as trees grow	Takes time; land is needed; trees can die or burn	Parks, farms, catchments and woodland areas	A new woodland may store carbon over decades.
Public transport improvements	Reduces car journeys if people use it	Needs investment and regular services	Town and city transport networks	A bus route can reduce many separate car trips.
Carbon capture	Captures carbon dioxide from some industrial sources	Expensive and not suitable for every source	Large factories, cement works or power stations	Could help where emissions are difficult to avoid.

Evaluation question: Which two solutions should the town prioritise? Use evidence and explain one limitation of each.

Model answer:

The town should prioritise home insulation and public transport improvements. Home insulation could reduce heating emissions by about 20% in improved homes, which is useful in the UK because many homes use energy for heating. A limitation is that insulation has an upfront cost and may disrupt households. Public transport improvements could reduce many separate car journeys if people choose buses or trains. A limitation is that services must be reliable and frequent, otherwise people may keep using cars. Wind power could also be useful, but it may need a regional or national plan rather than only a town decision.

Data Task 3: Emissions Source Pie Chart in Text

Simplified sources of a town's greenhouse gas emissions:

Heating buildings  | ############################ 35%
Transport          | ########################     30%
Electricity use    | ###############              18%
Agriculture        | ########                     10%
Waste              | #####                         7%

Questions:

1. Which source is the largest?
2. Which two sources together make 65%?
3. Suggest one targeted reduction for heating buildings.
4. Suggest one targeted reduction for transport.
5. Why should the town not focus only on the smallest source?

Model answers:

1. Heating buildings is the largest source at 35%.
2. Heating buildings and transport together make 65%.
3. The town could insulate homes and schools or use more efficient heating systems.
4. The town could improve buses, trains, cycle routes and walking routes, or reduce short car journeys.
5. The smallest source still matters, but focusing only on it would miss larger reductions from heating and transport.

Practical-Style Task: Modelling the Greenhouse Effect

This is a classroom model, not a perfect copy of the real atmosphere.

Method

1. Place two identical clear containers under the same lamp.
2. Put a temperature probe or thermometer in each container.
3. Put a clear cover over one container and leave the other uncovered, or use a teacher-prepared safe comparison of different gas conditions if available.
4. Measure the starting temperature in each container.
5. Switch on the lamp for 10 minutes.
6. Record the temperature every 2 minutes.
7. Repeat the investigation to check repeatability.

Safety:

• Do not touch hot lamps.
• Keep water and electrical equipment separate.
• Handle glass or clear plastic containers carefully.
• Follow teacher instructions for any gas samples.

Variables

Variable type	Example
Independent variable	Whether the container is covered or uncovered.
Dependent variable	Temperature change in degrees C.
Control variables	Same lamp, same distance from lamp, same container size, same starting temperature, same measuring time, same surface inside container.

Results Table

Time in minutes	Uncovered container temperature in degrees C	Covered container temperature in degrees C
0	20.0	20.0
2	21.5	22.1
4	22.7	24.0
6	23.3	25.4
8	24.0	26.3
10	24.5	27.1

Questions:

1. Write a prediction using scientific reasoning.
2. Calculate the temperature change for each container.
3. Which container warmed more?
4. Name two control variables.
5. How could the investigation be made more repeatable?
6. Give one limitation of this model compared with the real atmosphere.

Model answers:

1. I predict the covered container will warm more because less energy will escape from the container, so its temperature will rise faster.
2. The uncovered container changed from 20.0 to 24.5 degrees C, so the change was 4.5 degrees C. The covered container changed from 20.0 to 27.1 degrees C, so the change was 7.1 degrees C.
3. The covered container warmed more.
4. Control variables include the same lamp, same distance from the lamp, same container size and same measuring time.
5. Repeat the test several times and calculate a mean, using the same method each time.
6. The model is limited because the real greenhouse effect works mainly by greenhouse gases absorbing infrared radiation, while a covered container also traps warm air.

Practical-Style Task: Rock Weathering Investigation

This investigation models chemical weathering using chalk, limestone chips or plaster. It must be teacher-supervised.

Method

1. Put equal masses of chalk chips into three labelled beakers.
2. Add 50 cm3 of plain water to beaker A.
3. Add 50 cm3 of weak vinegar solution to beaker B.
4. Add 50 cm3 of stronger teacher-prepared dilute vinegar solution to beaker C.
5. Leave each beaker for 15 minutes.
6. Observe fizzing, cloudiness and changes in chip appearance.
7. Carefully remove, dry and measure the final mass if suitable.

Safety:

• Wear eye protection.
• Do not taste any liquid.
• Handle acidic solutions carefully.
• Clean spills straight away.
• Wash hands after the practical.

Variables:

Variable type	Example
Independent variable	Type or concentration of liquid.
Dependent variable	Change in mass, or visible change in the rock chips.
Control variables	Starting mass of chips, volume of liquid, time left, temperature, chip size.

Example results:

Beaker	Liquid	Starting mass in g	Final mass in g	Change in mass in g	Observation
A	Plain water	10.0	9.9	0.1	Very little change
B	Weak vinegar	10.0	9.3	0.7	Some fizzing
C	Stronger dilute vinegar	10.0	8.9	1.1	More fizzing and rougher chips

Questions:

1. What is the independent variable?
2. What is the dependent variable?
3. Name two control variables.
4. Which result shows the greatest change?
5. Suggest one way to improve accuracy.
6. Suggest one way to improve reliability.
7. What limitation does this model have?

Model answers:

1. The independent variable is the type or concentration of liquid.
2. The dependent variable is the change in mass of the chips, or the visible change.
3. Control variables include starting mass, volume of liquid, time, temperature and chip size.
4. Beaker C shows the greatest change, with a mass loss of 1.1 g.
5. Use a balance with smaller scale divisions and dry the chips in the same way before measuring.
6. Repeat each test and calculate a mean result.
7. The model is much faster than real weathering and uses simplified conditions.

Reading Comprehension: A UK Town Responds to Climate Change

A coastal town in the UK is reviewing how it uses energy and how it prepares for future climate risks. Local records show that several recent summers have been warmer than the average recorded in the late twentieth century. The town has also experienced a few episodes of heavy rainfall that caused surface flooding in low-lying streets. Scientists advising the council explain that one hot summer or one flood cannot by itself prove climate change. However, long-term records can show changes in average temperature, rainfall patterns and the frequency of some extreme events.

The council studies its main sources of greenhouse gas emissions. Heating homes and public buildings is a major source because many buildings use gas boilers and lose heat through roofs, walls and windows. Transport is another important source because many short journeys are made by car. The town considers insulating homes, improving bus services, adding cycle routes, installing solar panels on public buildings, protecting nearby woodland and improving drainage systems.

Each option has benefits and limitations. Insulation can reduce energy use and save money over time, but it can be expensive at the start. Better buses can reduce car journeys, but only if services are frequent, affordable and reliable. Tree planting can store carbon as trees grow, but it takes years and cannot replace the need to cut emissions. Improved drainage does not reduce emissions much, but it can help the town adapt to heavier rainfall by reducing flood risk.

The council decides that it needs both mitigation and adaptation. Mitigation means reducing the causes of climate change, such as greenhouse gas emissions. Adaptation means preparing for changes that are already happening or likely to happen. The final plan uses a mixture of evidence, cost, fairness and practical limits.

Reading Questions

1. Retrieve: Name two climate risks mentioned in the passage.
2. Define from context: What does mitigation mean?
3. Explain: Why might insulation reduce emissions?
4. Quote evidence: Give one phrase showing that scientists use cautious language.
5. Limitation: Why might better buses not reduce emissions as much as expected?
6. Opinion with evidence: Which option do you think is most useful for the town? Justify your answer.

Model Answers

1. Warmer summers and surface flooding after heavy rainfall are mentioned.
2. Mitigation means reducing the causes of climate change, such as greenhouse gas emissions.
3. Insulation reduces heat loss, so less fuel is needed for heating and less carbon dioxide is released.
4. One suitable quote is: "one hot summer or one flood cannot by itself prove climate change."
5. Better buses may not reduce emissions as much as expected if services are not frequent, affordable and reliable.
6. A justified answer could choose insulation because heating is a major source of emissions and insulation can reduce energy use. A strong answer should also mention a limitation, such as upfront cost.

Real-World Examples

Atmosphere and climate examples:

• Carbon dioxide in the atmosphere has been measured over many decades and has increased.
• UK average temperatures have risen compared with earlier long-term records.
• Heatwaves can affect health, water supply, farming and transport.
• Heavier rainfall can increase flood risk in some places.
• Melting glaciers and ice sheets contribute to sea level rise.

Carbon cycle examples:

• A woodland removes carbon dioxide during photosynthesis.
• A person or animal releases carbon dioxide during respiration.
• A compost heap releases carbon dioxide during decomposition.
• A car, gas boiler or power station releases carbon dioxide through combustion.
• Oceans can absorb carbon dioxide and can also release it.

Rock cycle examples:

• Basalt can form from cooling lava.
• Granite can form from slow cooling magma underground.
• Limestone may contain fossils and can form in marine environments.
• Sandstone forms from sand grains compacted and cemented.
• Slate forms when shale is changed by heat and pressure.

UK links:

• Limestone landscapes are found in parts of the UK.
• Coastal erosion changes cliffs and beaches.
• Quarrying provides useful building materials but affects landscapes and habitats.
• Flood risk influences where and how towns build.
• Wind, solar, hydroelectric and nuclear power can reduce reliance on fossil fuels where appropriate.

Careers linked to this topic include meteorologist, climate scientist, geologist, environmental scientist, engineer, energy analyst and conservation worker.

Common Misconceptions

Misconception	Correct scientific idea
The atmosphere is mostly oxygen.	Dry air is mostly nitrogen, with oxygen making up about one fifth.
Carbon dioxide does not matter because there is so little of it.	Small amounts of some gases can have large effects because they absorb infrared radiation.
The greenhouse effect is always bad.	The natural greenhouse effect keeps Earth warm enough for life. The enhanced greenhouse effect is the problem.
The ozone hole causes global warming.	Ozone depletion and climate change are different issues. The ozone layer absorbs much ultraviolet radiation; greenhouse gases absorb infrared radiation.
Weather and climate mean the same thing.	Weather is short-term conditions; climate is long-term patterns over many years.
A cold day proves climate change is not happening.	Climate change is about long-term averages and patterns, not one day in one place.
All climate change is natural, so humans cannot be causing current warming.	Climate has changed naturally before, but current rapid warming is strongly linked to human increases in greenhouse gases.
Plants solve climate change completely.	Plants absorb carbon dioxide, but tree planting cannot replace large emissions reductions.
The carbon cycle is only about carbon dioxide in the air.	Carbon is stored and transferred through air, living things, soil, oceans, rocks and fossil fuels.
Respiration is the same as breathing.	Breathing moves air; respiration is a chemical process in cells that releases energy.
Erosion and weathering are the same.	Weathering breaks rocks down in place; erosion moves rock or sediment away.
Rocks are permanent and never change.	Rocks can change over long time scales through the rock cycle.
Lava and magma are exactly the same.	Magma is molten rock below the surface; lava is molten rock at the surface.
Metamorphic rocks melt to form.	Metamorphic rocks form by heat and pressure without fully melting.
Every diagram of Earth layers is to scale.	Most classroom diagrams exaggerate layer thicknesses so they are easier to see.

Key Vocabulary

Term	Meaning	Example sentence
Atmosphere	Layer of gases around Earth	The atmosphere is held by gravity.
Nitrogen	Main gas in dry air	Nitrogen makes up about 78% of dry air.
Oxygen	Gas needed for aerobic respiration	Humans need oxygen for aerobic respiration.
Carbon dioxide	Gas used in photosynthesis and released by respiration and combustion	Carbon dioxide is a greenhouse gas.
Argon	Unreactive gas in air	Argon makes up about 0.9% of dry air.
Water vapour	Water as a gas	Water vapour can condense to form clouds.
Greenhouse gas	Gas that absorbs some infrared radiation	Methane is a greenhouse gas.
Greenhouse effect	Process where greenhouse gases keep Earth warmer by absorbing and re-emitting infrared radiation	The natural greenhouse effect supports life.
Infrared radiation	Radiation emitted by warm objects	Earth's surface emits infrared radiation.
Absorb	Take in energy	Carbon dioxide can absorb infrared radiation.
Emit	Give out energy	A warm surface emits infrared radiation.
Re-emit	Give out absorbed energy again	Greenhouse gases re-emit radiation in different directions.
Global warming	Rise in Earth's average global temperature	Global warming is linked to extra greenhouse gases.
Climate change	Long-term changes in climate patterns	Climate change includes altered rainfall and sea level rise.
Climate	Long-term pattern of weather	The UK has a temperate climate.
Weather	Short-term atmospheric conditions	Today's weather is rainy.
Carbon cycle	Movement of carbon between stores	Photosynthesis is part of the carbon cycle.
Carbon store	Place where carbon is held	Oceans are carbon stores.
Carbon transfer	Process moving carbon between stores	Feeding transfers carbon from plants to animals.
Photosynthesis	Process where plants use light to make glucose from carbon dioxide and water	Photosynthesis removes carbon dioxide from air.
Respiration	Chemical process in cells that releases energy from food	Respiration produces carbon dioxide.
Combustion	Burning reaction with oxygen	Combustion of petrol releases carbon dioxide.
Decomposition	Breakdown of dead organisms and waste	Decomposition returns carbon to soil and air.
Fossil fuel	Fuel formed from organisms over millions of years	Coal, oil and gas are fossil fuels.
Deforestation	Removal of forests	Deforestation reduces photosynthesis by trees.
Renewable energy	Energy from sources that are naturally replaced	Wind and solar power are renewable energy sources.
Crust	Thin solid outer layer of Earth	The crust contains surface rocks.
Mantle	Thick layer of hot, mostly solid rock below the crust	The mantle can slowly flow.
Core	Dense central part of Earth	The core is very hot and dense.
Mineral	Naturally occurring solid substance in rocks	Quartz is a mineral.
Rock	Naturally occurring material made of minerals	Granite is a rock.
Igneous rock	Rock formed when molten rock cools and solidifies	Basalt is an igneous rock.
Sedimentary rock	Rock formed from compacted and cemented sediment	Sandstone is sedimentary rock.
Metamorphic rock	Rock changed by heat and pressure without melting	Slate is metamorphic rock.
Molten rock	Rock that has melted	Molten rock can cool to form igneous rock.
Magma	Molten rock below Earth's surface	Magma can cool underground.
Lava	Molten rock at Earth's surface	Lava cools quickly after an eruption.
Weathering	Breakdown of rock in place	Freeze-thaw action is weathering.
Erosion	Movement of rock or sediment away	Rivers can cause erosion.
Transportation	Movement of sediment by water, wind or ice	Sand can be transported by a river.
Deposition	Dropping of sediment	Deposition happens when water slows.
Compaction	Sediment is squeezed by layers above	Compaction helps form sedimentary rock.
Cementation	Minerals glue sediment grains together	Cementation forms solid rock from sediment.
Heat	Energy linked to temperature	Heat can help form metamorphic rock.
Pressure	Force acting over an area	Pressure can change rocks underground.
Independent variable	Variable deliberately changed	In the weathering test, liquid type is the independent variable.
Dependent variable	Variable measured as the outcome	Temperature change is a dependent variable.
Control variable	Variable kept the same	Lamp distance should be a control variable.
Fair test	Test where only the independent variable is changed	Keeping container size the same helps make a fair test.
Anomaly	Result that does not fit the pattern	A sudden lower temperature reading may be an anomaly.
Reliability	How trustworthy results are when repeated	Repeats can improve reliability.
Repeatability	How close repeat results are when the same person uses the same method	Similar repeat results show good repeatability.
Accuracy	How close a measurement is to the true value	A calibrated thermometer improves accuracy.
Precision	How small the measurement divisions are or how close repeated values are	A probe reading to 0.1 degrees C is more precise than one reading to 1 degree C.

Practice Questions

Multiple Choice Questions

1. Which gas is most common in dry air? A. Oxygen B. Nitrogen C. Carbon dioxide D. Argon

2. Which statement about carbon dioxide is correct? A. It is the main gas in air. B. It cannot affect climate because there is very little of it. C. It absorbs some infrared radiation. D. It is not part of the carbon cycle.

3. What is the atmosphere? A. The solid outer layer of Earth B. The layer of gases around Earth C. The liquid part of the core D. The layer of molten rock at the surface

4. Which process removes carbon dioxide from the atmosphere? A. Combustion B. Photosynthesis C. Respiration D. Decomposition

5. What does climate mean? A. The weather on one day B. Long-term patterns of weather C. A single storm D. The amount of oxygen in air

6. Which rock type forms from compacted and cemented sediment? A. Igneous B. Sedimentary C. Metamorphic D. Molten

7. What is erosion? A. Rock breaking down in place B. Sediment being dropped C. Rock or sediment being moved away D. Magma cooling underground

8. Which is the best description of the mantle? A. Thin solid outer layer B. Thick layer of hot, mostly solid rock C. Gas layer around Earth D. Cold layer of sediment

9. Which human activity increases carbon dioxide in the atmosphere? A. Burning fossil fuels B. Condensation C. Deposition D. Cooling magma

10. Why is the natural greenhouse effect useful? A. It removes all carbon dioxide. B. It keeps Earth warm enough for life. C. It blocks all sunlight. D. It creates the ozone hole.

FillBlank Questions

1. The layer of gases around Earth is called the __________.
2. Dry air is about 78% __________.
3. A gas that absorbs some infrared radiation is called a __________ gas.
4. The rise in Earth's average global temperature is called __________.
5. The long-term pattern of weather is called __________.
6. Burning a fuel is called __________.
7. Rock breaking down in place is called __________.
8. The movement of sediment by water, wind or ice is called __________.
9. A rock formed by heat and pressure without melting is a __________ rock.
10. The variable that is deliberately changed is the __________ variable.

Short-Answer Questions

1. State the approximate percentages of nitrogen and oxygen in dry air.
2. Explain why carbon dioxide can be important even though it is only about 0.04% of dry air.
3. Describe the difference between weather and climate.
4. Explain why the ozone layer and greenhouse effect are not the same.
5. Name three carbon stores.
6. Explain how respiration affects atmospheric carbon dioxide.
7. Describe how sedimentary rock forms.
8. Explain the difference between magma and lava.
9. Give one benefit and one limitation of tree planting as a climate solution.
10. Why should scientists repeat practical measurements?

Diagram Questions

Use the rock cycle diagram earlier in the pack.

1. What process changes sediment into sedimentary rock?
2. What process changes metamorphic rock into magma or lava?
3. What process changes magma or lava into igneous rock?
4. Why is it wrong to say the rock cycle always follows one fixed route?

Use the greenhouse effect diagram earlier in the pack.

5. What happens to Earth's surface after sunlight reaches it?
6. What type of radiation is emitted by Earth's warm surface?
7. How does increasing greenhouse gas concentration affect energy in the Earth system?

Data Questions

Use the carbon dioxide and temperature table.

1. By how many ppm did carbon dioxide concentration increase from 1960 to 2025?
2. Which year had the highest temperature anomaly?
3. Why should scientists be careful when using one year's data?
4. Write a cautious conclusion about the relationship between carbon dioxide concentration and temperature anomaly.

Use the emissions source chart.

5. What percentage of emissions comes from transport?
6. Which source should be targeted first if the town wants the largest single reduction opportunity?
7. Suggest one solution for electricity use.

Practical Questions

1. In the greenhouse effect model, identify the independent variable.
2. In the greenhouse effect model, identify the dependent variable.
3. Give two control variables for the greenhouse effect model.
4. Why is the container model limited?
5. In the rock weathering investigation, why should the starting mass of chips be kept the same?
6. What is an anomaly?
7. How can repeatability be improved?

Longer 6-8 Mark Question

Explain how human activities can increase average global temperatures. In your answer, include:

• the greenhouse effect;
• carbon dioxide and at least one other greenhouse gas;
• examples of human activities;
• evidence from a data table;
• cautious scientific language.

Model Answers

Multiple Choice Answers

1. B. Nitrogen.
2. C. It absorbs some infrared radiation.
3. B. The layer of gases around Earth.
4. B. Photosynthesis.
5. B. Long-term patterns of weather.
6. B. Sedimentary.
7. C. Rock or sediment being moved away.
8. B. Thick layer of hot, mostly solid rock.
9. A. Burning fossil fuels.
10. B. It keeps Earth warm enough for life.

FillBlank Answers

1. atmosphere
2. nitrogen
3. greenhouse
4. global warming
5. climate
6. combustion
7. weathering
8. transportation
9. metamorphic
10. independent

Short-Answer Model Answers

1. Dry air is about 78% nitrogen and 21% oxygen.
2. Carbon dioxide can be important because it absorbs and re-emits some infrared radiation, so it contributes to the greenhouse effect even at a small concentration.
3. Weather is short-term atmospheric conditions, such as today's rain or temperature. Climate is the long-term pattern of weather over many years.
4. The ozone layer absorbs much ultraviolet radiation from the Sun. The greenhouse effect involves greenhouse gases absorbing infrared radiation emitted by Earth's surface.
5. Three carbon stores are the atmosphere, living organisms and oceans. Other correct answers include soils, fossil fuels and carbonate rocks.
6. Respiration adds carbon dioxide to the atmosphere because cells release energy from food and produce carbon dioxide.
7. Sedimentary rock forms when sediment is deposited in layers, compacted by layers above and cemented by minerals.
8. Magma is molten rock below Earth's surface. Lava is molten rock at the surface.
9. Tree planting can remove carbon dioxide as trees grow, but it takes time, needs land and cannot replace reducing fossil fuel emissions.
10. Repeating measurements helps scientists check repeatability, spot anomalies and improve reliability.

Diagram Model Answers

1. Compaction and cementation change sediment into sedimentary rock.
2. Melting changes metamorphic rock into magma or lava.
3. Cooling changes magma or lava into igneous rock.
4. The rock cycle can follow different routes because rocks can be weathered, buried, heated, melted or changed in different orders.
5. Earth's surface warms after sunlight reaches it.
6. Earth's warm surface emits infrared radiation.
7. Increasing greenhouse gas concentration means more infrared radiation is absorbed and re-emitted, so more energy remains in the Earth system.

Data Model Answers

1. Carbon dioxide increased by 106 ppm from 317 ppm to 423 ppm.
2. 2020 had the highest temperature anomaly in the table, at 1.01 degrees C.
3. One year's data may be affected by short-term variation, so long-term patterns are more useful for climate conclusions.
4. A cautious conclusion is: as carbon dioxide concentration increased, temperature anomaly generally increased too. This correlation is supported by the known mechanism that carbon dioxide absorbs infrared radiation, but one simplified table alone is not enough evidence for the whole explanation.
5. Transport produces 30% of the town's emissions.
6. Heating buildings should be targeted first if the town wants the largest single reduction opportunity because it is 35%.
7. A solution for electricity use is switching to low-carbon electricity sources such as wind, solar, hydroelectric or nuclear power where appropriate, and using energy more efficiently.

Practical Model Answers

1. The independent variable is whether the container is covered or uncovered.
2. The dependent variable is the temperature change in degrees C.
3. Control variables include same lamp, same distance from lamp, same container size, same starting temperature and same measuring time.
4. The container model is limited because it may trap warm air, while the real greenhouse effect mainly depends on gases absorbing and re-emitting infrared radiation.
5. The starting mass must be kept the same so differences in final mass are due to the liquid, not because one beaker had more rock at the start.
6. An anomaly is a result that does not fit the pattern.
7. Repeatability can be improved by repeating the same method several times and comparing the results or calculating a mean.

Longer 6-8 Mark Model Answer

Human activities can increase average global temperatures by increasing the concentration of greenhouse gases in the atmosphere. The natural greenhouse effect happens when sunlight warms Earth's surface. The warm surface emits infrared radiation. Greenhouse gases such as carbon dioxide, methane, water vapour and nitrous oxide absorb and re-emit some of this infrared radiation, keeping more energy in the Earth system.

The natural greenhouse effect is useful because it keeps Earth warm enough for life. However, burning coal, oil and gas releases extra carbon dioxide. Deforestation can also increase carbon dioxide because fewer trees are available to remove it by photosynthesis. Farming and landfill can release methane, and some fertilisers can increase nitrous oxide.

Evidence from the data table shows that carbon dioxide concentration rose from 317 ppm in 1960 to 423 ppm in 2025. Over the same period, the temperature anomaly generally increased from -0.02 degrees C to 0.95 degrees C. This supports the idea of a link between increasing carbon dioxide and warming.

A careful conclusion is that increasing greenhouse gas concentrations contribute to rising average global temperature because more infrared radiation is absorbed and re-emitted. The table shows a correlation, but scientists use many lines of evidence and the known greenhouse mechanism to explain why human activities are causing current warming.

Revision Checklist

Use this checklist before a quiz or test.

I can...	Confident?
Describe the crust, mantle, outer core and inner core.
Explain why Earth layer diagrams are often not to scale.
Define atmosphere and explain why gravity holds gases near Earth.
Recall that dry air is about 78% nitrogen and 21% oxygen.
Explain why carbon dioxide matters despite its small percentage.
Describe why the atmosphere matters for life.
Explain the difference between the ozone layer and greenhouse gases.
Explain the natural greenhouse effect in clear steps.
Distinguish the natural and enhanced greenhouse effect.
Define weather, climate, global warming and climate change.
Give examples of human activities that increase greenhouse gases.
Describe carbon stores and carbon transfers.
Explain photosynthesis, respiration, combustion and decomposition in the carbon cycle.
Interpret a carbon cycle diagram.
Compare igneous, sedimentary and metamorphic rocks.
Explain weathering, erosion, transportation and deposition.
Use evidence to identify rock types.
Interpret environmental data tables and text graphs.
Identify independent, dependent and control variables.
Explain fair testing, repeatability, reliability, accuracy, precision and anomalies.
Evaluate climate solutions using benefits and limitations.
Write a longer answer using scientific vocabulary and evidence.