Carbon Footprint – IGCSE Chemistry Definition

Carbon footprint is a newer addition to the 0620 syllabus that links chemistry to sustainability. Examiners typically ask for the definition, ways to reduce carbon footprint, and why reducing it matters. The focus is on practical actions with a chemical basis.

The 0620 definition

A carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, process, or person, usually expressed as a mass of CO₂ equivalent (e.g. kg CO₂e or tonnes CO₂e).

What contributes to a carbon footprint?

Activity	Greenhouse gas	Explanation
Burning fossil fuels for energy	CO₂	Combustion of hydrocarbons
Transport (cars, planes)	CO₂	Fuel combustion
Agriculture	CH₄	Cattle digestion, rice paddies
Manufacturing	CO₂	Energy for factories, chemical processes
Deforestation	CO₂	Less photosynthesis to absorb CO₂
Landfill	CH₄	Anaerobic decomposition of waste

Ways to reduce carbon footprint

Energy

• Use renewable energy (solar, wind, hydroelectric) instead of fossil fuels
• Improve insulation to reduce heating energy
• Use energy-efficient appliances and lighting

Transport

• Walk, cycle, or use public transport
• Use electric or hybrid vehicles
• Reduce air travel

Carbon capture

• Plant trees (photosynthesis absorbs CO₂)
• Carbon capture and storage (CCS) — capturing CO₂ from power station emissions and storing it underground

Lifestyle

• Reduce, reuse, recycle
• Eat less meat (cattle produce methane)
• Buy locally produced goods (less transport)

Worked exam question

A school wants to reduce its carbon footprint. (a) Define the term carbon footprint. [1] (b) Suggest two ways the school could reduce its carbon footprint. [2]

Mark scheme

(a) The total amount of CO₂ (and other greenhouse gases) produced / emitted by an activity / organisation / person [1]

(b) Any two valid suggestions, e.g.: install solar panels / use renewable energy [1]; improve building insulation / reduce energy use [1]; encourage cycling instead of driving [1]; plant trees [1]

Common exam mistakes

• Defining carbon footprint as “the amount of carbon you use” — it is specifically the greenhouse gas emissions, measured in CO₂ equivalents.
• Only mentioning CO₂ — methane and other greenhouse gases also contribute to a carbon footprint.
• Giving vague answers like “use less energy” without specifying how — the examiner wants practical, specific suggestions.