Correct use of radiative efficiencies in calculating global warming potentials and other emission metrics

The calculations of Global Warming Potentials (GWPs) and other related climate emission metrics should use radiative efficiencies that are calculated using the mean atmospheric mole fraction, rather than the surface mole fraction as is commonly used. We quantify this correction and show it leads to an upward revision of GWP values. For species with lifetimes greater than a few years, the revision is an increase of a few percent e.g., 7 % for trichlorofluoromethane (CFC-11). For species with lifetimes of the order of a year or less, this correction can lead to increases in the GWPs of over ten percent, which could impact on stakeholder decisions on the desirability of using such gases.