365 Days of Climate Awareness 319 — Global Warming Potential
Global warming potential (GWP) is the analytical method for comparing different greenhouse gases.
Global warming potential (GWP) is the analytical method for comparing different greenhouse gases. They differ both in their absorptive capacity, known as “radiative efficiency”, and in their residence time, known as lifetime, in the atmosphere. The combination of those two yields the gas’ total potential for warming the planet. In these calculations as in other measures, water vapor, itself a very powerful greenhouse gas, is not included because it is not considered “well-mixed”. That is to say, concentrations of H2O vapor vary very widely in time and space around the world due to weather and climatic conditions.
Global warming potential is treated as a scalar: that is to say, a number without units, because all greenhouse gases are compared to carbon dioxide. CO2, by definition, has a GWP of 1. Since the gases have vastly different lifetimes: carbon dioxide, roughly 120 years, methane roughly 10.4, and CFCs less than that, their warming potential is averaged into a 100-year span. A few principle gases, using this 100-year average, are listed below. (For concentrations: ppm = parts per million; ppb = parts per…
