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Definition

Carbon Emissions

Carbon emissions strictly mean carbon dioxide (CO2) releases, although business reports often use the phrase loosely for all greenhouse gas emissions converted to carbon dioxide equivalent (CO2e).

What are carbon emissions?

Carbon emissions strictly mean carbon dioxide (CO2) releases. Company reports often use the phrase loosely for all greenhouse gas (GHG) emissions. Carbon dioxide equivalent (CO2e) expresses each gas's warming effect as the amount of CO2 with the same effect.

Why do carbon emissions matter to you?

Customers may ask for three separate emissions categories in tonnes CO2e. The CDP reporting platform's 2026 Questions 7.6, 7.7 and 7.8 do this. Australia's AASB S2 climate-reporting standard asks in-scope entities for the same totals in paragraph 29(a).

Where does the number come from?

Write down the companies, sites, sources and reporting period included before you calculate. Scope 1 covers sources you own or control. Scope 2 covers purchased electricity, steam, heat and cooling. Scope 3 covers other indirect emissions, including suppliers, travel and the use of sold products. For each source, multiply an activity record, such as litres or kWh, by an emission factor, meaning emissions per unit. Convert every result to the same unit before adding it, and do not combine CO2-only results with factors that cover several greenhouse gases.

What mistakes should you avoid?

  • Calling a CO2-only result CO2e.
  • Mixing kilograms and tonnes. One metric tonne equals 1,000 kg.
  • Calling one source or scope your whole carbon footprint.
  • Comparing totals that cover different companies, sites, periods or scopes.

Are carbon emissions and GHG emissions the same?

No. CO2 is one greenhouse gas; GHG emissions include CO2 and other gases. CO2e puts them on one comparable basis.

Why are emissions reported in tonnes CO2e?

One tonne is 1,000 kg. CO2e lets different gases be added, but only if the factor or calculation covers them.

Is a carbon footprint the same as carbon emissions?

A carbon footprint is a total for a stated boundary and period. Emissions may mean that total or only one source or scope. Label the figure so the reader knows which one you mean.

Example

Hypothetical example: A Singapore office records 48,000 kWh of grid electricity for 2024. Singapore's Energy Market Authority publishes a 2024 average grid emission factor of 0.402 kg CO2/kWh (Singapore Energy Statistics 2025, Chapter 2).

48,000 kWh x 0.402 kg CO2/kWh = 19,296 kg CO2. Divide by 1,000 to report 19.296 metric tonnes CO2.

Do not relabel this result as 19.296 tonnes CO2e. The official Singapore source states CO2, not CO2e. A full GHG total needs factors that cover the other gases before it can be reported in tonnes CO2e.

Where it comes up

Related terms

Sources

  • GHG Protocol

    Scope 1, Scope 2 and Scope 3 boundaries; use of activity records and emission factors; inventory boundary and unit discipline

    2026-08-18

  • CDP

    2026 full and SME question numbers for Scope 1, Scope 2 and Scope 3 emissions, including metric-tonne CO2e units

    2026-08-18

  • Singapore Energy Market Authority

    Singapore's 2024 average grid emission factor of 0.402 kg CO2/kWh used in the worked example

    2026-08-18

Sources checked 2026-08-18

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Carbon Emissions Definition | Keslio