The Greenhouse Effect
How carbon dioxide and methane warm the planet: where these greenhouse gases come from, how they absorb and re-emit the infrared radiation from the Earth surface, the effects of climate change, and how a carbon footprint can be cut.
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Why the planet is warming
Some gases in the air keep the planet warm enough to live on, but too much of them warms it further and changes the climate. The two main greenhouse gases you must know are carbon dioxide, released mainly by burning fossil fuels, and methane, released by farming such as cattle and rice and by rotting waste in landfill. These gases work by absorbing the infrared radiation given off by the warmed Earth surface and sending some of it back down. This module covers the gases, the mechanism, the effects on the climate, and how to cut a carbon footprint.
Climate words
Learn these before you sort any cause or effect, and be ready to explain the mechanism precisely.
Carbon dioxide against methane
The two main greenhouse gases come mostly from different human activities. Learn which comes from where.
How to explain the warming
Do not just say the gases trap heat. Describe the mechanism step by step: sunlight warms the surface of the Earth, the warmed surface gives off infrared radiation, the greenhouse gases take in that infrared, and they send some of it back down towards the surface, keeping it warmer than it would otherwise be. More gas means more of this happening. When you suggest cutting a carbon footprint, give a practical, justified action rather than a bare word.
Match the source to the gas
- burning coal, oil and gas
- cattle and rice farming
- rotting waste in landfill
- petrol and diesel car engines
- releases carbon dioxide from fossil fuels
- releases methane from agriculture
- releases methane as waste breaks down
- releases carbon dioxide from burning fuel
How does the greenhouse effect work?
Which statement explains the greenhouse effect mechanically?
- Greenhouse gases absorb infrared from the Earth surface and re-emit some of it back down.
- The gases simply trap heat like a blanket.
- The gases block sunlight from reaching the ground.
- The gases turn oxygen into heat.
Effects of climate change
Select the TWO possible consequences of global climate change.
- Rising sea levels
- More extreme weather
- A steadily cooling planet
- No change to rainfall anywhere
Add up the footprint saving
A family cuts its yearly carbon footprint by 3 units through using the car less and by a further 2 units through insulating the home. Add these to find the total units saved. What is the answer?
Order the greenhouse mechanism
Put the steps of the greenhouse effect in order, earliest first.
- Sunlight passes through the air and warms the Earth surface
- The warmed surface gives off infrared radiation
- Greenhouse gases absorb this infrared radiation
- They re-emit some of it back down, keeping the surface warmer
Complete the facts
A gas that warms the planet, such as carbon dioxide or methane, is a _____ gas. Burning fossil fuels releases carbon _____. Farming and rotting landfill waste release _____. The total greenhouse gas given off over the life of a product or a person is its carbon _____.
Match the action to its effect
- driving a petrol car every day
- insulating a home well
- switching to renewable electricity
- sending lots of food waste to landfill
- raises the carbon footprint with carbon dioxide
- lowers the footprint by wasting less energy
- lowers the footprint by burning no fossil fuel
- raises emissions by releasing methane
Spot the true greenhouse facts
Tap the TWO statements that are true about greenhouse gases.
- Burning fossil fuels releases carbon dioxide
- Greenhouse gases absorb and re-emit infrared radiation
- Greenhouse gases block sunlight from the ground
- More greenhouse gas cools the planet down
Judge the greenhouse case
Read each case and choose the best answer.
- A student writes that greenhouse gases work by trapping heat like a blanket. How could this be improved?
- A power station burns coal to make electricity. Which greenhouse gas does this mainly release?
- A family wants a practical way to cut its carbon footprint. Which is the best justified measure?
Explain the greenhouse effect
Explain how carbon dioxide and methane cause the greenhouse effect and climate change, and how a carbon footprint can be reduced.
- Name the two main greenhouse gases and a human source of each
- Explain the greenhouse effect mechanically, using infrared radiation
- Explain one consequence of climate change
- Explain one practical, justified way to cut a carbon footprint