Figure 6-15: Bar charts of radiative forcing
in 2050 (a) from all perturbations (from IPCC, 1996), (b) from subsonic aviation
(Fa1), and (c) from the additional effect due to supersonic air traffic. Note
scale change from (a) to (b) and (c). In (b), best estimate (bars) and high-low
67% probability intervals (whiskers) are given. No best estimate is shown
for cirrus clouds; rather, the dashed line indicates a range of possible estimates.
The evaluations below the graph are relative appraisals of the level of scientific
understanding associated with each component. In (c), white bars denote the
direct effect of the supersonic fleet (HSCT1000), whereas the black bars display
the change resulting from the displaced subsonic air traffic.