Figure 2.20: Global mean radiative forcings from the agents and mechanisms
grouped by agent type. Anthropogenic radiative forcings and the natural direct
solar radiative forcing are shown. Columns indicate other characteristics of
the radiative forcing; efficacies are not used to modify the radiative forcings
shown. Time scales represent the length of time that a given radiative forcing
term would persist in the atmosphere after the associated emissions and changes
ceased. No CO2 time scale is given, as its removal from the atmosphere
involves a range of processes that can span long time scales, and thus cannot
be expressed accurately with a narrow range of lifetime values. [Chapter
2, IPCC (2007) ]
