Atmospheric greenhouse gas concentrations, aggregated level assessment

Key messages

(04 Oct 2020)

The total concentration of all greenhouse gases and other forcing agents, including cooling aerosols, reached 457 parts per million CO₂ equivalents in 2018. If this concentration continues to increase at the present decadal rate, concentrations could, in the next few years, exceed the peak level that the Intergovernmental Panel on Climate Change states should not be exceeded if — with a 67 % likelihood — the global temperature increase is to be limited to 1.5 ^oC above pre-industrial levels by the end of the century. The peak concentrations corresponding to a temperature increase of 2 ^oC could be exceeded before 2034.

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