Global Warming Potential

Global-warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide.

A GWP is calculated over a specific time interval, commonly 20, 100 or 500 years. GWP is expressed as a factor of carbon dioxide (whose GWP is standardized to 1).

For example, the 20 year GWP of methane is 86, which means that if the same mass of methane and carbon dioxide were introduced into the atmosphere, that methane will trap 86 times more heat than the carbon dioxide over the next 20 years.

Factors that influence GWP

• The absorption of infrared radiation by a given species.
• The spectral location of its absorbing wavelengths.
• The atmospheric lifetime of the species.

Thus, a high GWP correlates with a large infrared absorption and a long atmospheric lifetime. According to IPCC (Intergovernmental panel on climate change) AR-5 released in 2013, GWP of methane is 86, Nitrous oxide is 268, Carbon tetrafluoride is 4950, HFC is 3790, CFC is 7020 for 20yrs.