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 one.

GWP is based on a number of factors, including the radiative efficiency (heat-absorbing ability) of each gas relative to that of carbon dioxide, as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of carbon dioxide.[1] The Intergovernmental Panel on Climate Change (IPCC) provides the generally accepted values for GWP, which changed slightly between 1996 and 2001 (eg methane was assessed a value of 21 in 1996). An exact definition of how GWP is calculated is to be found in the IPCC's 2001 Third Assessment Report.

Examples:

• carbon dioxide has a GWP of exactly 1 (since it is the baseline unit to which all other greenhouse gases are compared.)
• methane has a GWP of 23.
• nitrogen dioxide has a GWP of 296
• the hydrofluorocarbon HFC-23 has a GWP of 12000
• trifluoromethyl sulfur pentafluoride has a GWP of 18000 recently dubbed a super greenhouse gas.^[1]. The source is anthropogenic but the research shows the source is not sulfur hexafluoride.
• sulfur hexafluoride (SF₆) has the highest charted GWP of 22,200, used as high voltage insulator.

External links

• List of Global Warming Potentials and Atmospheric Lifetimes from the U.S. EPA
• IPCC 2001 Third Assessment Report page on Global Warming Potentials
• ^[1] Gas phase protonation of trifluoromethyl sulfur pentafluoride Federico Pepi , Andreina Ricci , Marco Di Stefano and Marzio Rosi Phys. Chem. Chem. Phys., 2005, 7 (6), 1181 - 1186[2]