Which of the following is used as a reference to measure the Global Warming Potential (GWP) of a greenhouse gas?

Carbon dioxide is the reference gas for global warming potential, assigned a value of 1.

Every other gas has its potential expressed as a multiple of carbon dioxide.

Methane has a potential many times higher than carbon dioxide and so cannot be the baseline.

Chlorofluorocarbons have very high potential values measured against carbon dioxide.

Hydrofluorocarbons also have high potential values expressed relative to carbon dioxide.

The potential compares heat trapped by a gas to the same mass of carbon dioxide over a set period.