Global warming potential
Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. It is a relative scale which compares the gas in question to that of the same mass of carbon dioxide (whose GWP is by definition 1). A GWP is calculated over a specific time interval and the value of this must be stated whenever a GWP is quoted or else the value is meaningless. Global warming potential (GWP) factor of C02 equivalents over a 100 year lifetime Greenhouse Gas / Global Warming Potential (GWP) Factor Carbon dioxide / 1 Methane / 21 Nitrous oxide / 290 Halocarbons (HFC) / 140 to 11,700 Sulphur Hexafluoride / 22,000 Source: Redefining Zero, RICS, London 2010, based on IPCC Third Assessment Report ? Climate Change 2001