The greenhouse effect
The Earth’s atmosphere acts as a greenhouse. It traps some of the heat from the sun close to the ground. This keeps the Earth warm and makes it habitable for humans. The greenhouse effect is a good thing.
The atmosphere consists mostly of nitrogen (77 %) and oxygen (21 %), the last 2 % includes a lot of different other gasses. A few specific gasses in the atmosphere cause the greenhouse effect and thereby keep the Earth warm.
The most important greenhouse gasses are
- Carbon dioxide, CO2
- Methane, CH4
- Nitrous oxide, N2O
Water vapour is also a greenhouse gas, but it is very unevenly spread in the atmosphere.
We talk about man-made climate change because humans have changed the natural content of greenhouse gasses in the atmosphere. We have for example increased CO2 levels through the burning of coal and oil.
Coal and oil are burned to heat up houses, petrol for cars etc.
Methane is a particular strong greenhouse gas and is emitted through for example the burps of cows.