Emission er for eksempel røgen fra skorstenen på et kraftværk eller fra udstødningsrøret på en bil.

The release of a pollutant, normally a gas, into the atmosphere.

In the context of climate change, emission normally refers more narrowly to a greenhouse gas released into the atmosphere.

The burning of fossil fuel and the resulting emission of the greenhouse gas carbon dioxide has been identified by the IPCC as the primary cause of the current global warming.

To mitigate global warming, the Kyoto Protocol was established under the UNFCCC.

This led to an agreement to put a cap on the emission of CO2. Each country can then only emit a certain quota.

If a country is not able to stay below the agreed emission limit, it can buy carbon credits. This process is also called emissions trading.

Regional and national attempts to limit emissions are sometimes more drastic. This kind of climate legislation will often include carbon taxes. Whether this is more effective than emissions trading is controversial.