Figure 6.8: Time evolution
of global mean radiative forcing from pre-industrial times (1750) to present.
Annual mean radiative forcing values are shown, except for stratospheric aerosols
of volcanic origin where a three-year running mean is used. Radiative forcings
due to (a) well-mixed greenhouse gases, tropospheric O3 , and stratospheric O3
, (b) direct effect of sulphate aerosols, fossil fuel organic and black carbon
aerosols, and biomass burning aerosols, (c) solar irradiance variations from Lean
et al. (1995) and Hoyt and Schatten (1993), respectively, and (d) stratospheric
aerosols of volcanic origin from Sato et al. (1993) (and updated with data from
www.giss.nasa.gov) for the period 1850
to 1998 and from Robock and Free (1996) for the period 1750 to 1988 (for the Northern
Hemisphere only). Note the change of scales in the different panels.