The carbon footprint of the school run
Choose how you get to school, how far it is, and for how many days. See how many kilograms of carbon dioxide the trips put into the air, and how many trees it would take a year to soak it up.
Core concept
Burning petrol and diesel gives carbon dioxide, a greenhouse gas: kg of CO₂ = km travelled × kg per km per person, so walking or cycling gives none, a shared bus gives little, and a car gives the most for each student
Topic: Our planet and sky
Every litre of petrol or diesel burned in an engine puts about 2.3 kg of carbon dioxide: A gas we breathe out. Plants take it in to make their food. All key words (CO₂) into the air. CO₂ is a greenhouse gas: it traps heat and warms the Earth. Your carbon footprint is the CO₂ your activities cause. For travel, it depends on how far you go and how. A car carrying one student gives about 0.17 kg of CO₂ for every kilometre; a motorbike about 0.07 kg; a school bus, shared by many students, only about 0.03 kg for each of them; walking and cycling give none. A grown tree takes in about 21 kg of CO₂ a year, so we can compare a footprint with the trees needed to soak it up.
What you will learn
- Work out the CO₂ from a trip as distance × CO₂ per km.
- Compare the footprint of different ways of travelling.
- Suggest ways to make a daily journey cleaner.
Before you start
- Know that burning fuel gives carbon dioxide.
Materials
- The distance from your home to school (ask an adult or use a map)
Equipment
- None
Procedure
- Record the school bus, 5 km each way, for a school year of 250 days.
- Change to a car and record.
- Change to a bicycle (or walking) and record.
How this simulation is simplified
- CO₂ per km per student: bicycle or walking 0, school bus 0.03 kg, motorbike 0.07 kg, car with one student 0.17 kg (typical values).
- Each school day has a trip there and back; a grown tree absorbs about 21 kg of CO₂ a year.