Carbon Footprint

Greenhouse gases include carbon dioxide, methane, nitrous oxide and several others. Because these gases trap heat to different degrees, they are converted into carbon dioxide equivalent, often written as CO2e, so that they can be added together.

For organisations, a carbon footprint is typically measured using the Greenhouse Gas Protocol, which divides emissions into Scope 1, direct emissions; Scope 2, indirect emissions from purchased energy; and Scope 3, all other indirect emissions in the value chain.

For example, a company’s carbon footprint would include emissions from its vehicles and boilers, from the electricity it buys and from producing the goods it buys and the use of the products it sells.

Measuring carbon footprints helps organisations understand where their emissions come from, set reduction targets and report their progress. Investors measure the carbon footprint of their portfolios, often expressed relative to the amount invested or revenues of the companies held. Carbon footprint calculations depend on estimates and assumptions, especially for indirect emissions, so results can vary between methods.