Carbon footprint

Climate change is an urgent global risk to people, economies and natural systems. Human greenhouse-gas (GHG) emissions are the principal driver of recent warming, making a credible inventory of those emissions an essential starting point for organisations seeking to understand and reduce their contribution.

When to use it

• Use the footprint to ask: “How effectively are we limiting climate impact while operating the business?”
• Treat it as a corporate-social-responsibility and operational KPI.
• Establish boundaries, methods, sources, ownership and reporting frequency before calculating totals.
• Compare performance with the base year, reduction pathway, sector peers and applicable targets.

Origins

The term “carbon footprint” developed from the ecological-footprint work of William Rees and Mathis Wackernagel in the early 1990s and entered wider use around the turn of the millennium. Corporate accounting became more standardised through collaboration between the World Resources Institute and World Business Council for Sustainable Development. Their GHG Protocol initiative began in nineteen ninety-eight and issued the first Corporate Standard in two thousand and one, providing the foundation for the now-familiar Scope one, Scope two and Scope three classification.

What it is

Perspective: Corporate social responsibility perspective.

Key performance question: How well do we safeguard the environment in the execution of our business operations?

A carbon footprint expresses the greenhouse gases attributable to an individual, organisation, activity or product as carbon-dioxide equivalent (CO2-eq). Converting different gases into a common unit allows their warming effects to be aggregated over a defined time horizon.

Measurement supports reduction, compliance, risk management and transparent communication. Regulation, customer expectations, investor scrutiny and physical climate risk can make poor emissions performance financially and reputationally consequential. A footprint is not itself an environmental outcome; its value comes from the quality of the boundary, data and decisions that follow.

How to use it

Measurement

Data collection method

Collect activity data from fuel and electricity records, production systems, refrigerant logs, purchasing data, freight, waste, product life cycles and business travel. Where direct measurement is unavailable, combine verified activity quantities—such as litres of fuel or passenger-kilometres—with appropriate emission factors.

Formula

Report the footprint in tonnes of CO2-eq for a stated period, commonly one year. A basic calculation multiplies activity data by an emission factor and converts non-CO2 gases using their global-warming potentials. Per-person figures vary widely; an illustrative historical estimate placed the average North American footprint near 20 tonnes of CO2-eq a year.

An older distinction separates primary and secondary footprints. The primary footprint covers direct emissions from fossil-fuel combustion for energy and transport. A fuel-efficient vehicle lowers direct fuel emissions, while an efficient light reduces the energy demand associated with its use. Fossil-fuel CO2 has historically represented about 82% per cent of anthropogenic GHG emissions worldwide.

The secondary footprint covers indirect life-cycle emissions from purchased products and services. A plastic water bottle, for example, carries emissions from raw materials, manufacture and transport; unnecessary packaging generally adds to this footprint.

For corporate reporting, the GHG Protocol’s scopes are usually clearer: Scope one covers direct controlled emissions, Scope two purchased energy and Scope three other value-chain emissions. State which framework and gases are included so the result can be reproduced.