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Regarding the forcing from black carbon vs. aerosols, we must be aware that the two are not equivalent.

Aerosols include tiny particles of black carbon, but also include a vast number of other tiny floating particles and droplets. Hansen says that aerosols are the second largest human-made forcing, but says it is probably negative:

From Hansen et al.:
The second largest human-made forcing is probably atmospheric aerosols, although the aerosol forcing is extremely uncertain. Our comparison of the various forcings...assumes that the aerosol forcing increment is half as large as the greenhouse gas forcing but opposite in sign. This aerosol forcing can be described as an educated guess.

Black carbon is estimated to be the second largest warming human-made forcing by Bond et al. 2013, but aerosols overall, including secondary effects, are a substantial net cooling human-made forcing, also discussed in Bond et al. They increase the global albedo by reflecting sunlight away before it can reach the ground, and by contributing to cloud formation.

Figure 10.1 shows that pollution sources rich in black carbon are warming short-term net forcing, even including other cooling aerosols. But it also shows that total aerosol forcing is substantially negative at about -1 watts per square meter.

PDF of Bond et al. (hefty at 19 megabytes)
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