1. Water vapour.
2. Carbon dioxide.
3. Methane.

1. Deforestation has meant that there are fewer trees remaining to absorb CO₂, and if the trees were burned they would have released CO₂.
2. Burning fossil fuels has released CO₂.
3. Farming of animals such as cows have produced large amounts of methane via their digestive processes.
4. As microorganisms break down our waste in landfill sites it releases CO₂.  

The greenhouse effect is the process by which heat energy is trapped within our atmosphere by greenhouse gas molecules.

1. Solar radiation from the sun passes through the atmosphere and hits the earth.
2. The earth absorbs this energy and reemits it as longer wavelength radiation towards space.
3. Some of the longer wavelength energy makes it all the way to space, but much is absorbed by small molecules called greenhouse gases.
4. These molecules then reemit the energy and the whole process of absorption and emission can happen over and over again.
5. This trapped energy keeps the atmosphere warmer and more stable than it would otherwise be.

1. Melting ice caps.
2. Rising sea levels.
3. Reduced biodiversity.
4. Changed migration patterns.
5. Increased frequency and severity of extreme weather events, such as heatwaves and droughts.