Global warming potential
Global warming potential (GWP) is an emissions metric that compares the time-integrated radiative forcing caused by a pulse emission of a greenhouse gas with that caused by the same mass of carbon dioxide over a selected time horizon, commonly 100 years.
In simple terms
A gas can absorb heat strongly but remain in the atmosphere briefly, or act less strongly over a much longer period. GWP combines these effects over a chosen horizon and assigns carbon dioxide a reference value of one. Multiplying a gas’s mass by the selected GWP converts it to carbon dioxide equivalent. Values can differ between scientific assessments and horizons, so a calculation should identify the source and horizon used.
Why it matters
GWP enables carbon accounting systems to aggregate several greenhouse gases into a comparable total. It also affects inventories, targets, and reported footprints because changing the assessment value, emission factor, or time horizon changes the calculated total. The metric is useful for consistent reporting, but it does not make different gases physically interchangeable or predict every temperature outcome.
Example
For example, an inventory can take a measured mass of methane, apply the 100-year GWP from its named assessment source, and express the result as tonnes of carbon dioxide equivalent. Repeating the calculation with a different time horizon would produce a different comparison value.
How it differs
Carbon dioxide equivalent
Global warming potential is a dimensionless comparison factor for a selected gas and time horizon; carbon dioxide equivalent is the quantity obtained when that factor is applied to a gas’s mass.