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Term of the week


This is the abbreviation of Million Tonnes of carbon dioxide equivalent. 1 tonne is equal to 1,000 kilograms.

This unit allows us to compare the potential warming impact of an emission of:

  • one greenhouse gas (like nitrous oxide)


  • an emission of the same amount of carbon dioxide.


Example: The global warming potential for nitrous oxide over 100 years is 298. This means that:

  • emissions of one million tonnes of nitrous oxide

is equivalent to


  • emissions of 298 million tonnes of carbon dioxide (298 Mt CO2eq).

Related terms:

Carbon sequestration and storage
This involves removing carbon emissions from the air and storing it securely for a long period.

Example: Carbon dioxide can be captured and stored by forests and oceans.

Carbon sinks
A carbon sink is a natural or artificial reservoir like plants, peat bogs or oceans. It soaks up and stores greenhouse gases like carbon dioxide. This process removes greenhouse gas from the air and it keeps our temperatures from getting too high.
Carbon emissions
Carbon emissions are created when particular gases are released into the air from activities like burning fossil fuels for energy. It includes gases like carbon dioxide and methane. This is because they both contain carbon.

‘Carbon emissions’ is sometimes used as a shorthand to describe all greenhouse gases.

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