What does GWP-100 mean?

GWP-100 measures the total warming effect of a gas over 100 years relative to CO2. It is the most commonly used time horizon in climate policy.

Why is methane GWP so much higher than CO2?

Methane absorbs infrared radiation about 80 times more effectively than CO2 over 20 years, but it breaks down faster, so the 100-year GWP is 28.

The Intergovernmental Panel on Climate Change (IPCC) publishes GWP values in its assessment reports. The latest values come from the AR6 report.

Convert greenhouse gas emissions into CO2-equivalent values using Global Warming Potential (GWP) factors over a chosen time horizon.

Mass of Gas Emitted

GWP Factor (relative to CO2)

CO2-Equivalent

2,800.0 kg CO2e

CO2-Equivalent (tonnes)2.800 tonnes CO2e

CO2-Equivalent vs Mass of Gas Emitted

Global Warming Potential (GWP) compares the heat-trapping ability of a greenhouse gas to CO2 over a specified period, typically 100 years.

CO2-Equivalent (kg) = Mass of Gas (kg) x GWP Factor

Common GWP-100 values: Methane (CH4) = 28, Nitrous Oxide (N2O) = 265, SF6 = 23,500. A higher GWP means the gas traps more heat per kilogram than CO2.

A farm releases 100 kg of methane (GWP = 28) over a year.