GWP (Global Warming Potential)

Global Warming Potential (GWP) is a metric used to compare the relative impact of different greenhouse gases (GHGs) on global warming. It measures how much energy the emissions of 1 ton of a gas will absorb over a given period of time, compared to the emissions of 1 ton of carbon dioxide (CO2). The larger the GWP, the more that a given gas warms the Earth compared to CO2 over that time period.

Time Horizons for GWP

The GWP values are typically calculated over specific time horizons, most commonly 20 years and 100 years, due to the differing lifetimes of GHGs in the atmosphere. This provides a measure of the immediate and long-term impacts of these gases on the atmosphere:

20-Year Time Horizon: Highlights the short-term impacts of GHGs. It's particularly useful for gases like methane (CH4), which have a shorter atmospheric lifetime but a high short-term impact on global warming.
100-Year Time Horizon: Provides a measure of the long-term impact of GHGs. This is the more commonly used time frame, especially in global climate agreements and policies.

GWP Values for Common GHGs

Below is a table showcasing the GWP values for some common greenhouse gases over both 20-year and 100-year time horizons:

Greenhouse Gas	Chemical Formula	GWP (20 years	GWP (100 years)
Carbon Dioxide	CO2	1	1
Methane	CH4	84-87	28-36
Nitrous Oxide	N2O	264-268	265-298
HFC-134a	C2H2F4	3830	1430
SF6	Sulfur Hexafluorid	17300	23500